10.14639/0392-100X-N2193
Epidermoid cysts are benign slow-growing developmental lesions resulting from ectodermal tissue that can localise anywhere in the body. Only 7% of all epidermoid cysts are located in the head and neck area and, together with dermoid cysts, account for less than 0.01% of all oral cavity cysts. Herein, we present the case of a 17-year-old male diagnosed with a sublingual epidermoid cyst and a review of the literature on this rare localisation, focusing on clinical and imaging features, management and outcomes. All the articles reporting epidermoid cysts located in oral cavity were searched using PubMed/Medline, discarding all those not located in head and neck district, not mentioning diagnostic imaging, not defined as epidermoid cysts by a histopathological diagnosis, and those for which only an abstract was available. In literature there were 35 articles, from 1993 to 2020, that meet the aforementioned requirements, for a total of 38 patients and 39 cysts. For each article, age, sex, onset time of symptoms, location, size and surgical access were analysed. Particular attention was paid to the radiological investigation used in order to understand the most common imaging aspects and also rare cases with unusual presentations.
text/xml
1827-675X
2193
en
Lorenzo Preda
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
review of reported cases
Imaging features of epidermoid cyst located in the floor of the mouth: case report and narrative review of literature
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Reviews
2023-02-27
2022-06-24
2023-02-28
2023-02-28
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1
Lorenzo Preda
2023/02/27
10.14639/0392-100X-N2193
3
Radiology Unit, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy; Radiology Unit 1, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
1827-675X
review of reported cases
en
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Imaging features of epidermoid cyst located in the floor of the mouth: case report and narrative review of literature
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ACTA OTORHINOLARYNGOLOGICA ITALICA 2023;43:3-11; doi: 10.14639/0392-100X-N2193




Review


Imaging features of epidermoid cyst located
in the floor of the mouth: case report and narrative
review of literature
Caratteristiche imaging di una cisti epidermoide nel pavimento orale:
case report e review narrativa della letteratura
Nicoletta Basla¹, Domenico Sfondrini², Marina Francesca Achilli¹, Michele Catalano¹, Francesco Sanvito¹,
Maria Gabriella Sala3, Stefano Marelli2, Marco Benazzo4,5, Lorenzo Preda¹,3
1
  Radiology Unit, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Pavia, Italy; 2 Maxillo-facial
Surgery Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; 3 Radiology Unit 1, Fondazione IRCCS Policlinico San Matteo,
Pavia, Italy; 4 Otorhinolaryngology Unit, Department of Clinical, Surgical, Diagnostic and Pediatric Sciences, University of Pavia,
Pavia, Italy; 5 Otorhinolaryngology Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy


SUMMARY
Epidermoid cysts are benign slow-growing developmental lesions resulting from ectoder-
mal tissue that can localise anywhere in the body. Only 7% of all epidermoid cysts are
located in the head and neck area and, together with dermoid cysts, account for less than
0.01% of all oral cavity cysts. Herein, we present the case of a 17-year-old male diagnosed
with a sublingual epidermoid cyst and a review of the literature on this rare localisation,
focusing on clinical and imaging features, management and outcomes. All the articles re-
porting epidermoid cysts located in oral cavity were searched using PubMed/Medline, dis-
carding all those not located in head and neck district, not mentioning diagnostic imaging,
not defined as epidermoid cysts by a histopathological diagnosis, and those for which only
an abstract was available. In literature there were 35 articles, from 1993 to 2020, that meet
the aforementioned requirements, for a total of 38 patients and 39 cysts. For each article,            Received: June 24, 2022
age, sex, onset time of symptoms, location, size and surgical access were analysed. Particu-           Accepted: September 28, 2022
lar attention was paid to the radiological investigation used in order to understand the most
common imaging aspects and also rare cases with unusual presentations.                                 Correspondence
                                                                                                       Nicoletta Basla
KEY WORDS: epidermoid cyst, mouth, diagnosis, review of reported cases                                 Radiology Unit, Department of Clinical, Surgical,
                                                                                                       Diagnostic and Pediatric Sciences, University of
RIASSUNTO                                                                                              Pavia, viale Camillo Golgi 19, 27100 Pavia, Italy
                                                                                                       Tel. +39 0382 503761; + 39 0382 501315
Le cisti epidermoidi sono lesioni benigne, a lenta crescita, derivanti dal tessuto ectodermi-          E-mail: nicoletta.basla01@universitadipavia.it
co e possono localizzarsi in qualsiasi parte del corpo. Solo il 7% si localizza nel distretto
testa-collo e, sommate alle cisti dermoidi rappresentano meno dello 0,01% di tutte le lesio-
ni cistiche della cavità orale. Le cisti epidermoidi localizzate all’interno della cavità orale          How to cite this article: Basla N, Sfondrini D,
                                                                                                         Achilli MF, et al. Imaging features of epidermoid
sono rare e generalmente rinvenute in pazienti giovani adulti, senza significativa prevalen-
                                                                                                         cyst located in the floor of the mouth: case report
za di genere. È presentato il caso di un maschio di 17 anni, con diagnosi di cisti epidermoi-            and narrative review of literature. Acta Otorhi-
de sublinguale, e una revisione della letteratura su questa rara localizzazione, puntando                nolaryngol Ital 2023;43:3-11. https://doi.
l’attenzione sulle caratteristiche cliniche, sull’imaging radiologico, il trattamento scelto e i         org/10.14639/0392-100X-N2193
dati istologici. Tutti gli articoli analizzati nella revisione della letteratura sono stati reperiti
tramite database PubMed/Medline; sono stati scartati i casi di cisti non situate nel distretto         © Società Italiana di Otorinolaringoiatria
testa-collo, gli articoli dove non è menzionata alcuna diagnostica strumentale, o dove la              e Chirurgia Cervico-Facciale

diagnosi istologica di cisti epidermoide non è stata confermata.
                                                                                                                      OPEN ACCESS
In letteratura sono riportati 35 articoli, dal 1993 al 2020, che soddisfano i suddetti requisi-
ti, per un totale di 38 pazienti e 39 cisti. Per ogni articolo sono stati analizzati: età e sesso,     This is an open access article distributed in accordance with
tempo di insorgenza dei sintomi, posizione e dimensioni, e accesso chirurgico. Particolare             the CC-BY-NC-ND (Creative Commons Attribution-Non-
                                                                                                       Commercial-NoDerivatives 4.0 International) license. The
attenzione è stata rivolta all’indagine radiologica scelta, al fine di comprendere gli aspetti         article can be used by giving appropriate credit and mentio-
di imaging più comuni e anche casi rari con presentazioni insolite.                                    ning the license, but only for non-commercial purposes and
                                                                                                       only in the original version. For further information: https://
PAROLE CHIAVE: cisti epidermoide, bocca, diagnosi, revisione dei casi in letteratura                   creativecommons.org/licenses/by-nc-nd/4.0/deed.en




                                                                                                                                                                   3
N. Basla et al.




Introduction                                                       first (ultrasonography US) and second levels (computed to-
                                                                   mography CT, or magnetic resonance MRI) are required,
Dermoid cysts are malformations lined with squamous epi-
                                                                   together with cytologic examination following fine-needle
thelium and usually the term “dermoid” is used indistinctly        aspiration biopsy (FNAB) 7.
to define dermoid cysts, epidermoid cysts, and teratoid            Surgical excision is the treatment of choice and the ap-
cysts. These can be classified according to the epithelial         proach depends on the location and size of the lesion 9.
components and the degree of differentiation of the ele-           The access can be with an extraoral incision if the lesion is
ments that compose them 1,2.                                       located under the geniohyoid muscle, or with an intraoral
Epidermoid cysts are coated with simple squamous epi-              approach if it is located above the mylohyoid muscle 7.
thelium and have a fibrous wall. True dermoid cysts (or            Prognosis is good, with a very low incidence of recurrence.
compound cysts) consist in an epithelial-lined cavity with         Malignant changes have been recorded in dermoid cysts,
keratinization and with skin appendages in the cyst wall,          but not in the floor of the mouth, with a 5% rate of malig-
like sebaceous and sweat glands, hair and hair follicles.          nant transformation for the teratoid type 7.
Finally, teratoid cysts (or complex cysts) may be covered          We present a rare case of epidermoid cyst located in the
in different types of epithelium and contain derivatives of        sublingual space, and discuss the radiological findings by
ectoderm, mesoderm and endoderm, such as bone, muscle,             collecting and comparing other evidence from the litera-
gastrointestinal and respiratory tissue 2,3.                       ture.
The differential diagnosis of dermoid cysts of the floor of
the mouth includes mucus extravasation phenomenon, em-
bryological anomalies, infection (such as acute bacterial          Case report
infection/cellulitis of the oral floor, sialadenitis, viral lym-   A 17-year-old teenager presented to his general practitioner
phadenitis), infectious and non-infectious granulomatous           complaining of a submental swelling, appearing approxi-
disease, non-granulomatous inflammatory disease, benign            mately one year earlier, with an increase in size in the last
or malignant tumour of the salivary glands, normal fat tis-        six months. After physical examination, in the suspicion of
sue in the submental/mandibular area, HIV-related lym-             submental lipoma, an ultrasound (US) examination was re-
phadenopathy 3,4.                                                  quested, along with ENT surgical evaluation for possible
The aetiology of the dermoid and epidermoid cysts is un-           excision.
known, although several theories have been proposed 5.             The physical examination conducted by the ENT specialist
Medial epidermoid cysts of the floor of the mouth can be           in August 2021 revealed a 5 cm soft swelling, fixed with
the result of entrapped ectodermal tissue of the first or sec-     respect to the deep planes, regular contours, without ten-
ond branchial arches, which fuse during the 3rd or 4th week        derness.
of gestation. A second theory is a surgical or accidental          US showed a 40 mm wide and inhomogeneous cystic le-
event conditioning a traumatic implantation of epithelial          sion. The cyst content was hypoechoic, with some hyper-
cells into deeper tissues. Finally, another hypothesis is that     echoic spots. No apparent vascularisation was identified
these cysts are a variant of thyroglossal duct cysts 5. Usu-       with colour Doppler US. These findings were considered
ally they present as solitary masses, but can sometimes be         suspicious for lipoma or cyst with particulate content
multiple 5. Epidermoid cysts located in the oral cavity are        (Fig. 1A).
rare and usually found in young adult patients without sig-        A second level imaging MRI scan (Figs. 1B-G) was per-
nificant gender prevalence. Only 7% of all the epidermoid          formed. The images showed a well-circumscribed, non-en-
cysts are located in the head and neck area which, together        hancing, cyst. The cyst content was homogeneously hyper-
with dermoid cysts, account for less than 0.01% of all oral        intense on T2 weighted images, and iso-hypointense on T1
cavity cysts 6.                                                    weighted images. Diffusion Weighted Imaging (DWI) and
Epidermoid cysts are rarely located in the floor of the            the corresponding Apparent Diffusion Coefficient (ADC)
mouth, primarily in the sublingual, submaxillary, or sub-          map did not reveal a restriction of water molecule diffu-
mandibular spaces 7. When located in the lower part of the         sion. No signal suppression was identified on fat-saturated
neck, they must be differentiated from thyroid nodules 8.          images.
Usually they are asymptomatic, but in some cases they              The lesion was located medially under the geniohyoid mus-
can interfere with mastication, swallowing, speaking and           cle, contacted the inferior side of the mylohyoid muscle,
breathing. Moreover, an infection can occur but rarely             and, laterally, the belly of the digastric muscle.
causes a life-threatening situation 4.                             In consideration of the imaging features, we posed a hy-
For diagnosis, ENT surgical evaluation and imaging of              pothesis of epidermoid cyst.



4
                                                                                                            Imaging of epidermoid cyst in the floor of the mouth




Figure 1. The images above show, respectively, in the first row sonographic appearance of the cyst, with posterior enhancement artifact and hyperechoic spots
(A). In T2w images on axial (B) and sagittal (C) plans it appears homogeneously hyperintense. It appears slightly hypointense in T1w (D) and isointense in T1w Fat
Sat images (E). There is no pathological restriction of signal on diffusion weighted images (F) and the respective apparent diffusion coefficient map (G).
As seen on the sagittal plane, the lesion is located under the geniohyoid muscle, dislocating inferiorly the mylohyoid muscle.


Other possible differential diagnoses were excluded. An                            Surgery was performed under general anaesthesia, with an
infectious hypothesis was discarded because the US did                             extraoral incision, because the cyst was located under the
not demonstrate vascularisation of the lesion. A lipoma                            geniohyoid muscle.
was ruled out since it did not have fatty components. The                          The surgical act was a median cervical incision extended
hypothesis of teratoid cyst was not convincing, consider-                          for about 5 cm, detachment and isolation of the neoforma-
ing its homogeneous features. Given the location along the                         tion, removed by blunt way. The procedure ended with hae-
median line of the oral floor, the hypotheses of ranula and                        mostasis, placement of suction drain, irrigation and layered
thyroglossal duct cysts were also considered; however, in                          suturing.
accordance with the ultrasound appearance they were sub-                           On macroscopic evaluation, the surgical specimen ap-
sequently discarded. In fact, the thyroglossal duct cyst in                        peared as a yellowish/white smooth oval mass, measuring
the suprahyoid area is typically located in the median area                        approximately 50 × 40 × 45 mm, soft in consistency and
in relation to the foramen cecum. Usually the epicentre is                         cystic in nature (Fig. 2A). Histopathological microscopic
at the base of the tongue or in the posterior part of the floor                    examination of the surgical specimen showed a cystic for-
of the oral cavity. The ranula is located in the anterior por-                     mation with pultaceous content, with histological features
tion of the sublingual space, usually lateralised. It has the                      typical for epidermoid cyst as shown in Figures 2B, C.
appearance of a “horseshoe-shaped” cystic formation. The                           Clinical evaluation carried out 6 months after surgery
diving/plunging ranula develops mainly in the subman-                              showed no residual disease.
dibular space with an anterior tail in the sublingual space.
Furthermore, both the thyroglossal duct cyst and the ranula
appear anechoic or hypoechoic, presenting slight hyper-
                                                                                   Review of the literature
echogenicity only in cases of infection.                                           Although there are manuscripts in the literature concerning



                                                                                                                                                                5
N. Basla et al.




Figure 2. Surgical specimen: the cyst was entirely removed and has intact and well-defined walls (A). Histopathological microscopic appearance of the surgical
specimen: cystic formation with pultaceous content (B, C).


cystic lesions of the head and neck district, there are no                       muscle. In one case the cyst herniated through the geni-
reviews that specifically deal with epidermoid cysts in the                      ohyoid muscle.
oral floor, focusing in particular on the diagnostic approach                    Figure 3 briefly outlines the possible anatomical locations
and therapeutic management.                                                      and the relationships with the muscular structures, also
All the articles published up to December 2021 reporting                         guiding the surgical approach.
epidermoid cysts located in oral cavity were searched on                         Regarding the first diagnostic approach, in 15 cases
PubMed/Medline, using as keywords “epidermoid cyst                               (38.46%) US was performed, in 14 (35.90%) a CT scan,
submental”, “epidermoid cyst oral cavity”, “epidermoid                           and only in 9 cases (23.08%) an MRI. In several cases, ad-
cyst of the floor of the mouth”.                                                 ditional in-depth diagnostic investigations were performed.
All of the following were discarded: lesions not located in                      Out of a total of 56 diagnostic investigations carried out,
head and neck district, articles not discussing diagnostic im-                   US and MRI were both performed in 16 cases (41%), and
aging techniques, absence of histopathological diagnosis of                      CT in 25 cases (64.1%), basing the percentage on the total
epidermoid cysts, or absence of a full-text manuscript. Our                      number of cysts.
search yielded 35 articles, in a time frame of 27 years (1993-                   By US, the findings were: in 3 cases hypoechoic aspect,
2020), including 39 lesions in 38 patients 1-37. Table I summa-                  in 2 cases hyperechogenic aspect without ever finding an
rises the main data on the articles retrieved from the literature.               inhomogeneous appearance, where specified.
Of 38 patients, 21 were male (55.3%) and 17 female                               The most common appearance of epidermoid cyst in a CT
(44.7%). Age range was 2-79 years; the mean age was                              scan was a hypodense round lesion, found in 21 cases.
30 ± 20 years (34 in males and 29 in females).                                   While in MRI the epidermoid cysts were described as iso-
Only in one case, reported by Sahoo et al. 14, a 55-year-old                     hypointense in T1 weighted images and hyperintense in
woman presented with two cysts.                                                  T2 weighted images, Zielinski et al. 11 and Sahoo et al. 14
The mean onset time of the cysts was about 40 months.                            reported 3 cysts that were hyperintense in T1, Zielinski et
The most common symptoms reported were difficulty in                             al. 11 and De Ponte et al. 5 reported 2 cases of hypointensity
swallowing (11 patients) and speech (10 patients), 5 pa-                         in T2.
tients presented with dysphagia, and only 3 with dyspnoea;                       Due to the wide time range of the studies reported in the lit-
finally, 15 patients were asymptomatic.                                          erature, we do not have specific data about the appearance
Sorting by anatomic position, when specified, all the 19                         of the lesion in DWI sequences and in the respective ADC
cysts were classified according to their position relative                       maps, nor in post-contrast T1w sequences.
to geniohyoid and mylohyoid muscles in three catego-                             As is known, surgical excision of lesions is definitive
ries:                                                                            therapy and this depends on the relationship with the su-
• above the geniohyoid and mylohyoid muscle: 7 cysts;                            prahyoid muscles. Of the 31 cases for which the type of
• between geniohyoid and mylohyoid muscles: 7 cysts;                             surgical strategy was known, 17 cysts were excised with
• beneath geniohyoid and mylohyoid muscles: 5 cysts.                             an intraoral approach, while 14 were approached using
Of these, in only 2 cases were the cysts included in both                        an extraoral technique. Of these, 3 cysts were treated
categories 2 and 3, as they herniated through the mylohyoid                      both intra- and extra-orally. Only for 14 out of 39 cysts



6
                                                                                                        Imaging of epidermoid cyst in the floor of the mouth




Table I. Summary of the main data of the clinical cases from the articles selected in the literature.
 Author      Gender       Age          Location             Symptomatology                 Size (mm)       First imaging         Time        Treatment
                        (years)                                                                            (all imaging)         onset
                                                                                                                               (months)
 Kandogan         M         11           Sublingual        Difficulty chewing and          40 x 35               RM               36          Extra-oral
 et al.,                                                  swallowing of solid foods
 2007 1
 Utumi et al.,     F        15               -                        No                      45            CT (CT - MR)           6          Extra-oral
 2016 10
 Zielinski et     M          6               -                        No                 27 x 25 x 19            US                3          Extra-oral
 al., 2014 11                                                                                                (US - MRI)
 Zielinski et      F        15               -                        No                 29 x 26 x 24       US (US - CT)           6          Extra-oral
 al., 2014 11
 Baliga et al.,    F        26               -               Altered speech and            30 x 30               US               36          Intra-oral
 2014 12                                                     functional difficulty
 Patil et al.,    M         28               -                       No                  30 x 20 x 20            US                5              ?
 2009 2
 Silveira et      M         26           Sublingual        Speech and swallowing           70 x 70               US               24              ?
 al., 2019 13                                                     difficulties
 Sahoo et          F        55           Submental         Difficulty in speech and           40         US (US - CT - MR)         6          Intra-oral
 al., 2017 14                                                     swallowing
 Sahoo et                                Sublingual                     -                     30         US (US - CT - MR)
 al., 2017 14
 Verma et          F        16               -            Difficulty in chewing and      70 x 50 x 45       CT (CT - MR)           5          Intra-oral
 al., 2012 15                                             swallowing of solid foods
 Mirza et al.,    M         43               -                         No                83 x 77 x 50    US (US - CT - MR)         -          Extra-oral
 2014 4
 Lohaus et         F        19               -                        No                 50 x 50 x 38    US (US - CT - MR)         3          Extra-oral
 al., 1999 16
 Bitar et al.,     F        17       Herniating through Difficulty in chewing and        80 x 51 x 47       CT (CT - MR)           -          Extra-oral
 2003 17                            the mylohyoid, from swallowing solid food
                                     the floor of mouth
                                       to the thyroid
                                          cartilage
 Calderon et      M          2           Sublingual                  No                    30 x 20               US                -          Intra-oral
 al., 1993 18
 Thibouw et       M         73           Sublingual         Difficulty in speaking       70 x 40 x 35       CT (CT - MR)         0.13         Intra-oral
 al., 2020 6
 Pascual et        F         3           Sublingual                   No                   20 x 15          CT (CT - MR)           2          Intra-oral
 al., 2015 19
 Soares et        M         45               -             Limitation in mouth           50 x 30 x 20       CT (CT - MR)           -          Intra-oral
 al., 2015 20                                             opening and speech,
                                                          dysphagia, dyspnoea
 De Ponte et      M         18               -             Difficulty breathing,              45                 RM                -          Intra-oral
 al., 2002 5                                            swallowing and speaking
 Tsirevelou        F        14      Over the geniohyoid              No                    14 x 12          CT (CT - MR)          10          Intra-oral
 et al.,                                  muscle
 2009 7
 Tsirevelou        F        35               -             Dysphagia, dysarthria,             21            CT (CT - MR)           6          Extra-oral
 et al.,                                                   dyspnoea on exertion
 2009 7
 Datta et al.,    M         24        Submandibular           Right-sided neck             50 x 30       US (US - CT - MR)        8.5            Both
 2020 21                                                          swelling
 Findik et al.,   M         10        Submandibular                  No                  40 x 30 x 40            RM                -          Extra-oral
 2017 9
                                                                                                                                              continues    u




                                                                                                                                                           7
N. Basla et al.




Table I. Summary of the main data of the clinical cases from the articles selected in the literature (follows).
 Author      Gender       Age          Location             Symptomatology                 Size (mm)               First imaging        Time      Treatment
                        (years)                                                                                    (all imaging)        onset
                                                                                                                                      (months)
 Klibngern et      F         26        Left sublingual                 No                   65 x 32 x 25                RM               6        Intra-oral
 al., 2020 22                               space
 Assaf et al.,     M         39        Right sublingual     Dysphagia, progressive              50                      RM                -       Intra-oral
 2012 23                                    region           snoring during sleep,
                                                            occasional shortness of
                                                                      breath
 Tandon et         F         23        From sublingual      Difficulty in swallowing,         80 x 50               CT (CT - MR)         36       Intra-oral
 al., 2014 24                           area to thyroid     mastication, and speech
                                             notch
 Nishar et         M         60        Submandibular                   No                     103 x 81            US (US - CT - MR)     360       Extra-oral
 al., 2016 25                                region
 Gulati et al.,    M         16         Left sublingual      Difficulty in swallowing       62 x 60 x 57                RM               3          Both
 2015 26                                     space
 Yilmaz et         F         34         Left sublingual                No                   75 x 45 x 60                RM              120       Intra-oral
 al., 2006 27                                region
 Yilmaz et         M         35       Suprahyoid region      Difficulty in swallowing       50 x 70 x 80                RM              240       Extra-oral
 al., 2006 27
 Brunet-           M         43       Ssublingual space     Difficulty in swallowing,         80 x 50                    TC              24       Intra-oral
 Garcia et                                                  mastication, and speech
 al., 2018 28
 Behl et al.,      M         22        Sublingual space     Dysphagia, difficulties in        100 x 80                   TC               -       Extra-oral
 2001 29                                                             speech
 Turetschek        F         25        Sublingual space       Swelling, increasing            60 x 50             US (US - CT - MR)       -       Intra-oral
 et al., 1995                                                difficulties in speech
 30


 Gordon et         F         79           Sublingual                Swelling                29 x 27 x 53            CT (CT - MR)          -       Extra-oral
 al., 2013 31
 Kinzer et al.,    M         40                -                       No                   55 x 45 x 25                RM                -           ?
 2006 32
 Kudoh et          M         69           Submental                    No                   40 x 30 x 25            CT (CT - MR)         24       Intra-oral
 al., 2013 33
 Banerjee et       F         61         Submandibular           Swelling, supine              68 x 48             US (US - CT - MR)       -       Intra-oral
 al., 2011 34                                               dyspnoea, almost unable
                                                            to speak or eat anything
                                                                 including fluid
 Mammen et         M         57           Under the              Mildly painful,              38 x 30             US (US - CT - MR)      3        Extra-oral
 al., 2013 35                         platysma anterior     progressively increasing,
                                         to the right-              swelling
                                       submandibular
                                             gland
 Fung et al.,      M         50           Submental               Discomfort with                -                US (US - CT - MR)     Since       Both
 2008 36                                                            swallowing                                                        childhood
 Walstad et        F         23           Submental         Difficulty with swallowing      48 x 27 x 35            CT (CT - MR)           -      Extra-oral
 al., 1998 37                                                       and speech



was specified the location between the muscles of the                                   Discussion
oral floor. Moreover, even when known, the surgical ap-
proach was not always planned according to the location                                 Epidermoid cysts located in the oral cavity are uncommon
of the lesion, for example in Kandogan et al. 1, despite the                            and mostly found in young adult patients (30 ± 20 years
cyst was in the sublingual space, an extra-oral approach                                old) without significant gender prevalence.
was chosen.                                                                             Review of the literature showed that the main symptoms



8
                                                                                                            Imaging of epidermoid cyst in the floor of the mouth




  A                                                       B                                                    C




Figure 3. Different locations of epidermoid cysts of the oral cavity: under the mylohyoid and geniohyoid muscle (A); above the mylohyoid and geniohyoid muscle
(B); among the mylohyoid and geniohyoid muscle (C).


Table II. Indications on when to use different imaging techniques and iconographic features of epidermoid cysts.
                                        Indications                                                  Characteristics of epidermoid cyst
 US          First-line imaging method to detect the lesion and to formulate the       Cystic well-defined lesions with variable imaging features: homogeneous
                                 main diagnostic hypothesis                               hypoechoic content, hypoechoic with some hyperechoic spots, or
                                                                                            hyperechogenic aspect. No vascularisation with colour Doppler
 CT                              Only if MRI is not available                          Homogeneously hypodense or hypodense with hyperdense components.
                                                                                                Sometimes with post-contrast peripheral enhancement
 MRI           Second level diagnostic investigation, best imaging method to            Well-circumscribed, non-enhancing, cystic lesion, with homogeneous
            evaluate the location of the cyst and establish the surgical planning,    content hyperintense on T2w and iso-hypointense on T1w images, without
                in consideration of the position between the geniohyoid and              restriction of water molecule diffusion. No signal suppression in fat-
                                      mylohyoid muscles                                                            saturated images



are difficulties in swallowing and speaking, but almost half                         tween cystic and solid lesions, reproducibility of the imag-
of patients complained of no symptoms.                                               ing aspects of epidermoid cysts due to the literature review,
The most interesting data emerged from review of literature                          and finally the ability to accurately describe the localisation
is that MRI was performed in only 9 of 39 cases, although                            of the lesion among muscular structures surrounding the
it allows precise evaluation of the position of the mass with                        oral floor, this should be considered at least as a imaging of
the muscles of the oral floor (in particular mylo-hyoid and                          second level, after preliminary US examination, which is
genio-hyoid) that is essential for pre-operative planning.                           adequate for a first evaluation.
Moreover, despite the young age of most patients, CT was                             Table II presents a summary of US, CT, MRI indications
performed in many more cases than MRI, and together with                             and cyst epidermoid primary imaging features.
the US was the first line method. In 4 cases, all three imag-
ing modalities were used.
                                                                                     Conclusions
The reasons for the lack of use of MRI can be due to the
intrinsic disadvantages of the method, such as its high cost                         Epidermoid cysts of the oral cavity are rarely seen and even
and absolute and relative contraindications of execution.                            if they are uncommon, it is necessary to include them in the
The imaging features of the lesions were found to be quite                           differential diagnoses among lesions of the head and neck
overlapping in all patients among diagnostic investigations,                         district. As in our case, they frequently present as a solitary
in particular the hypodense aspect in CT, iso-hypointense                            lesion. Otolaryngological examination and US represent
aspect in T1 weighted sequences and hyperintense aspect                              the first step before surgery. MRI should be performed as
in T2 weighted sequences of MRI.                                                     a second level imaging modality, because it is essential to
Considering the great advantages of MRI such as the non-                             characterise the lesion and for surgical planning 4. When
use of ionising radiation, the ability to discriminate be-                           MRI is not available or is contraindicated, CT can be use-



                                                                                                                                                              9
N. Basla et al.




ful. Surgical removal of a sublingual epidermoid cyst is the                   8
                                                                                    Szczepanek-Parulska E, Ostałowska A, Antosik P, et al. An unu-
treatment of choice and the approach depends on the size                            sual neck mass in an adult: epidermoid cyst. Pol Arch Intern Med
                                                                                    2021;131:193-194. https://doi.org/10.20452/pamw.15803
and location of the lesion. In fact, whether extraoral or in-                  9
                                                                                    Findik Y, Topal O, Senturk MF, et al. Extraoral approach of the surgi-
traoral incision is preferred depends on the position of the                        cal treatment of sublingual epidermoid cyst: a case report. J Pak Med
lesion in relation to the muscles of the floor of the mouth                         Assoc 2017;67:796-798.
(primarily mylohyoid and geniohyoid). Therefore, the ra-                       10
                                                                                    Utumi ER, Araujo JP, Pedron IG, et al. Extensive epidermoid cyst
diological report should describe the relationship between                          of the submental region. Autops Case Rep 2016;6:51-54. https://doi.
                                                                                    org/10.4322/acr.2016.031
the mass and these suprahyoid muscles.                                         11
                                                                                    Zielinski R, Zakrzewska A. Submental epidermoid cysts in chil-
                                                                                    dren. Open Med (Wars) 2014;10:77-81. https://doi.org/10.1515/
Conflict of interest statement                                                      med-2015-0013
The authors declare no conflict of interest.                                   12
                                                                                    Baliga M, Shenoy N, Poojary D, et al. Epidermoid cyst of the floor
                                                                                    of the mouth. Natl J Maxillofac Surg 2014;5:79-83. https://doi.
Funding                                                                             org/10.4103/0975-5950.140185
This research did not receive any specific grant from fund-
                                                                               13
                                                                                    Silveira HA, Almeida LY, Dominguete MHL, et al. Intraoral epider-
                                                                                    moid cyst with extensive elastofibromatous changes: an unusual find-
ing agencies in the public, commercial, or not-for-profit                           ing. Oral Maxillofac Surg 2019;23:493-497. https://doi.org/10.1007/
sectors.                                                                            s10006-019-00785-y
                                                                               14
                                                                                    Sahoo RK, Sahoo PK, Mohapatra D, et al. Two concurrent large epi-
Author contributions                                                                dermoid cysts in sublingual and submental region resembling plung-
                                                                                    ing ranula: report of a rare case. Ann Maxillofac Surg 2017;7:155-
MGS, DS, LP, MB: conception and design; NB, MA, MC,                                 158. https://doi.org/10.4103/ams.ams_50_15
MGS, DS, MB, SM: provision of study materials or pa-                           15
                                                                                    Verma S, Kushwaha JK, Sonkar AA, et al. Giant sublingual epi-
tients; NB, MA, MC: collection and assembly of data;                                dermoid cyst resembling plunging ranula. Natl J Maxillofac Surg
NB, MA, MC: data analysis and interpretation; all authors:                          2012;3:211-213. https://doi.org/10.4103/0975-5950.111386
manuscript writing.                                                            16
                                                                                    Lohaus M, Hansmann J, Witzel A, et al. Ungewöhnlicher sonographis-
                                                                                    cher befund einer epidermoidzyste. Uncommon sonographic findings
                                                                                    of an epidermoid cyst in the head and neck. HNO 1999;47:737-740.
Ethical considerations                                                              https://doi.org/10.1007/s001060050454
The research was conducted ethically; the patient has filled                   17
                                                                                    Bitar MA, Kumar S. Plunging congenital epidermoid cyst of the oral
out informed consent before carrying out the instrumental                           cavity. Eur Arch Otorhinolaryngol 2003;260:223-225. https://doi.
investigations, in accordance with current European regula-                         org/10.1007/s00405-002-0555-x
tions, agreeing to voluntary participation in the study and                    18
                                                                                    Calderon S, Kaplan I. Concomitant sublingual and submental epider-
                                                                                    moid cysts: a case report. J Oral Maxillofac Surg 1993;51:790-792.
publication of data in anonymous form.
                                                                                    https://doi.org/10.1016/s0278-2391(10)80425-2
                                                                               19
                                                                                    Pascual Dabán R, García Díez E, González Navarro B, et al. Epider-
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