10.5826/dpc.1401a88
Introduction: Pigmented eccrine poroma (PEP) is a unique variant of a benign adnexal tumor known as eccrine poroma. Distinguishing PEPs from other pigmented lesions can be challenging due to overlapping clinical and dermoscopic features.
Objectives: To provide a comprehensive analysis of the dermoscopic, confocal (RCM), and histological features of PEPs.
Methods: We undertook a retrospective study of the clinical, dermoscopic, RCM and histopathological features of PEPs that were surgically excised and histopathologically recognized. Data on epidemiological, clinical, dermoscopic, RCM and histopathological features were collected from the databases of the Skin Cancer Unit, IRCCS Policlinico di Sant’Orsola, between January 2021 and May 2023.
Results: The study population consisted of 61 patients, including 34 females (55.7%) and 27 males (44.3%). Dermoscopic examination of 61 PEPs revealed the presence of irregular borders (55.7%), milia-like cysts (50.8%), brown pseudo-network (41%), cerebriform pattern (34.4%), comedo-like openings (29.5%), atypical vessels (26.2%), glomerular vessels (18%), fingerprint-like perifollicular structures (8.2%), dots (4.9%) and dotted vessels (4.9%). RCM imaging was collected from 11 cases and showed mostly well-defined tumor nests with small cells in 100% of cases, bright structures in the upper dermis representing melanocytes and melanophages (63.6%), dark round spaces within the tumor nests (54.5%), well-demarcated borders of the nest (45.5%) and dilated and prominent vessels in upper dermis (27.3%). Histopathological pattern analysis revealed PEP sensu stricto (PEPss) as the most frequent (54.1%).
Conclusions: The distinctive dermoscopic patterns, along with the confocal features aid in the differentiation from other pigmented lesions.
text/xml
2160-9381
3706
en
Emi Dika
https://creativecommons.org/licenses/by-nc/4.0
Dermatology Practical & Conceptual
adnexal tumor
Reflectance Confocal Microscopy Combined with Dermoscopy and Histology in the Diagnostic Setting of Pigmented Eccrine Poroma: a Retrospective Study
Text.Serial.Journal
https://dpcj.org/index.php/dpc
Original Article
2024-01-31
2023-07-20
2024-01-31
2024-02-21
e2024088
Dermatol Pract Concept
Introduction: Pigmented eccrine poroma (PEP) is a unique variant of a benign adnexal tumor known as eccrine poroma. Distinguishing PEPs from other pigmented lesions can be challenging due to overlapping clinical and dermoscopic features.
Objectives: To provide a comprehensive analysis of the dermoscopic, confocal (RCM), and histological features of PEPs.
Methods: We undertook a retrospective study of the clinical, dermoscopic, RCM and histopathological features of PEPs that were surgically excised and histopathologically recognized. Data on epidemiological, clinical, dermoscopic, RCM and histopathological features were collected from the databases of the Skin Cancer Unit, IRCCS Policlinico di Sant’Orsola, between January 2021 and May 2023.
Results: The study population consisted of 61 patients, including 34 females (55.7%) and 27 males (44.3%). Dermoscopic examination of 61 PEPs revealed the presence of irregular borders (55.7%), milia-like cysts (50.8%), brown pseudo-network (41%), cerebriform pattern (34.4%), comedo-like openings (29.5%), atypical vessels (26.2%), glomerular vessels (18%), fingerprint-like perifollicular structures (8.2%), dots (4.9%) and dotted vessels (4.9%). RCM imaging was collected from 11 cases and showed mostly well-defined tumor nests with small cells in 100% of cases, bright structures in the upper dermis representing melanocytes and melanophages (63.6%), dark round spaces within the tumor nests (54.5%), well-demarcated borders of the nest (45.5%) and dilated and prominent vessels in upper dermis (27.3%). Histopathological pattern analysis revealed PEP sensu stricto (PEPss) as the most frequent (54.1%).
Conclusions: The distinctive dermoscopic patterns, along with the confocal features aid in the differentiation from other pigmented lesions.
Emi Dika
2024/01/31
10.5826/dpc.1401a88
e2024088
Oncologic Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna; Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy
2160-9381
adnexal tumor
en
e2024088
Marchetti MA, Marino ML, Virmani P, et al. Dermoscopic features and patterns of poromas: a multicentre observational case-control study conducted by the International Dermoscopy Society. J Eur Acad Dermatol Venereol. 2018;32(8):1263-1271. DOI:10.1111/jdv.14729. PMID: 29194789. PMCID: PMC5984114.
Reflectance Confocal Microscopy Combined with Dermoscopy and Histology in the Diagnostic Setting of Pigmented Eccrine Poroma: a Retrospective Study
https://dpcj.org/index.php/dpc/article/download/3706/2450
        Reflectance Confocal Microscopy Combined
              with Dermoscopy and Histology
      in the Diagnostic Setting of Pigmented Eccrine
              Poroma: A Retrospective Study
       Federico Venturi1,2, Stephano Cedirian1,2, Martina Mussi1,2, Aurora Alessandrini1,2,
                                          Emi Dika1,2


1 Oncologic Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
2 Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum University of Bologna, Bologna, Italy



Key words: pigmented eccrine poroma, reflectance confocal microscopy, dermoscopy, adnexal tumor
Citation: Venturi F, Cedirian S, Mussi M, Alessandrini A, Dika E. Reflectance Confocal Microscopy Combined with Dermoscopy and
Histology in the Diagnostic Setting of Pigmented Eccrine Poroma: A Retrospective Study. Dermatol Pract Concept. 2024;14(1):e2024088.
DOI: https://doi.org/10.5826/dpc.1401a88
Accepted: July 9, 2023; Published: January 2024
Copyright: ©2024 Venturi et al. This is an open-access article distributed under the terms of the Creative Commons Attribution-
NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use,
distribution, and reproduction in any medium, provided the original authors and source are credited.
Funding: None.
Competing Interests: None.
Authorship: Federico Venturi and Stephano Cedirian contributed equally to this work and share first authorship. All authors have
contributed significantly to this publication.
Corresponding Author: Federico Venturi, MD, Dermatology Unit, IRCCS Azienda Ospedaliero-Universitaria di Bologna; Department of
Medical and Surgical Sciences Alma Mater Studiorum University of Bologna, Bologna, Italy. Via Massarenti, 1 - 40138 Bologna, Italy.
Ph: +39 051-2144849; Fax +39 051-2144867 E-mail: federico.venturi@hotmail.it




  ABSTRACT             Introduction: Pigmented eccrine poroma (PEP) is a unique variant of a benign adnexal tumor known
                       as eccrine poroma. Distinguishing PEPs from other pigmented lesions can be challenging due to over-
                       lapping clinical and dermoscopic features.
                       Objectives: To provide a comprehensive analysis of the dermoscopic, confocal (RCM), and histolog-
                       ical features of PEPs.
                       Methods: We undertook a retrospective study of the clinical, dermoscopic, RCM and histopathologi-
                       cal features of PEPs that were surgically excised and histopathologically recognized. Data on epidemi-
                       ological, clinical, dermoscopic, RCM and histopathological features were collected from the databases
                       of the Skin Cancer Unit, IRCCS Policlinico di Sant’Orsola, between January 2021 and May 2023.




Original Article | Dermatol Pract Concept. 2024;14(1):e2024088                                                                        1
                       Results: The study population consisted of 61 patients, including 34 females (55.7%) and 27 males
                       (44.3%). Dermoscopic examination of 61 PEPs revealed the presence of irregular borders (55.7%),
                       milia-like cysts (50.8%), brown pseudo-network (41%), cerebriform pattern (34.4%), comedo-like
                       openings (29.5%), atypical vessels (26.2%), glomerular vessels (18%), fingerprint-like perifollicular
                       structures (8.2%), dots (4.9%) and dotted vessels (4.9%). RCM imaging was collected from 11 cases
                       and showed mostly well-defined tumor nests with small cells in 100% of cases, bright structures in
                       the upper dermis representing melanocytes and melanophages (63.6%), dark round spaces within the
                       tumor nests (54.5%), well-demarcated borders of the nest (45.5%) and dilated and prominent vessels
                       in upper dermis (27.3%). Histopathological pattern analysis revealed PEP sensu stricto (PEPss) as the
                       most frequent (54.1%).
                       Conclusions: The distinctive dermoscopic patterns, along with the confocal features aid in the differ-
                       entiation from other pigmented lesions.




Introduction                                                      histopathological features were collected from the databases
                                                                  of the Skin Cancer Unit, IRCCS Policlinico di Sant’Orsola,
Eccrine poroma (EP) is a benign adnexal tumor, originating        Bologna, Italy between January 2021 and May 2023. This
from the sweat glands. It primary affects the acral regions,      study was approved by the Institutional Review Board. The
such as the palms and soles, given the higher concentration       inclusion criterion was the availability of the data of histo-
of eccrine sweat glands [1]. EP typically appears as an as-       pathologically diagnosed PEPs. Patients without relevant
ymptomatic solid, flesh-colored, nodular-like lesion between      medical records were excluded. All lesions were re-examined
4th and 6th decades of life, with no significant sex predom-      by two dermatopathologists specialized in the field. Dermo-
inance [2]. The exact cause of this condition is not known,       scopic images were collected through a digital video camera
but it may be associated with injuries, exposure to radia-        system (Medicam 800; FotoFinder Systems GmbH; origi-
tion, or scars [3]. Generally, EPs lack pigmentation, although    nal magnifications ×20–×40). Each dermoscopic image was
there are occasional cases where a pigmented variation can        then reviewed by 5 dermatologists (SC, MM, AA, ED, FV).
be observed (pigmented eccrine poroma [PEP]); this particu-       Concordance between dermatologists was considered when
lar variant is more frequent among individuals with darker        4 out of 5 agreed on the dermoscopic structure. While all
skin tones and, differently from the non-pigmented EP, is         the cases underwent dermoscopic and histologic examina-
typically located on the trunk [4].                               tion, 11 cases were analyzed with RCM. RCM images were
                                                                  acquired through VivaScope®, Lucid Inc.. Each RCM image
                                                                  was then reviewed by 2 experts in RCM (ED, FV). Concor-
Objectives
                                                                  dance between the above-mentioned experts was consid-
Our study provides a comprehensive analysis of the dermo-         ered when 2 out of 2 agreed on the RCM feature. Lastly,
scopic, confocal, and histological features of PEPs based on      the histopathological patterns were associated by our 2 der-
the evaluation of 61 cases collected from January 2021 to         mopathologists to 4 different histological variants of PEPs:
May 2023 at the Skin Cancer Unit, IRCCS Policlinico di            PEP sensu stricto (PEPss), Pigmented Poroid Hidroadenoma
Sant’Orsola, Bologna, Italy. The study, conducted by a group      (PPH), Pigmented Hidroacanthoma Simplex (PHS) and Pig-
of experts in dermoscopy, reflectance confocal microscopy         mented Dermal Duct Tumour (PDDT) [5]. The dermoscopic
(RCM) and histopathology enhances our knowledge of this           patterns, confocal features, and histological characteristics
rare entity to improve its differentiation from other pig-        were assessed for each case to identify specific features and
mented skin lesions.                                              aid in accurate diagnosis.


Methods                                                           Results
We undertook a retrospective study of the clinical, dermo-        The study population consisted of 61 patients with a histo-
scopic, RCM and histopathological features of PEPs that           logically confirmed diagnosis of PEP, including 34 females
were surgically excised and histopathologically recognized.       (55.7%) and 27 males (44.3%). Age at presentation ranged
Data on epidemiological, clinical, dermoscopic, RCM and           from 36 to 75 years (mean 66.5 years, median 64 years).




2                                                                     Original Article | Dermatol Pract Concept. 2024;14(1):e2024088
Mean age was 62.3 years for females and 67.6 years for               well-demarcated borders of the nest (45.5%) and dilated
males, respectively. Anatomical site was as follows: trunk           and prominent vessels in upper dermis (27.3%). Histopatho-
(44.3%), lower extremities/soles (27.9%), upper extremities/         logical pattern analysis revealed PEPss as the most frequent
palms (22.9%) and head and neck/scalp (4.9%).                        (54.1%) where a lobular growth pattern and broad connec-
    Dermoscopic examination of 61 PEPs revealed the                  tion to the overlying epidermis of poroid cells and cuticular
presence of irregular borders (55.7%), milia-like cysts
­                                                                    cells, with abundance of melanin, followed by PDDT (23%),
(50.8%), brown pseudo-network (41%), cerebriform pat-                PHS (19.7%) and PPH (3.8%).
tern (34.4%), comedo-like openings (29.5%), atypical vessels            Results are fully displayed in Tab.1.
(26.2%), glomerular vessels (18%), fingerprint-like perifollic-
ular structures (8.2%), dots (4.9%) and dotted vessels (4.9%).
                                                                     Conclusions
    RCM imaging was collected from 11 cases since the
technique was recently introduced and images weren’t avail-          EPs are a rare variant of a benign adnexal tumor originating
able for all cases. It showed mostly well-defined tumor nests        from the epithelium of the intraepidermal portion of eccrine
with small cells in 100% of cases, bright structures in the          sweat ducts, typically located on the acral regions, such as
upper dermis representing melanocytes and melanophages               the palms and soles, but they can also occur in non-acral
(63.6%), dark round spaces within the tumor nests (54.5%),           sites [3]. PEP corresponds to only 17% of cases of EP and it




 Table 1. Dermoscopic, reflectance confocal microscopy and histopathological features of pigmented
                          eccrine poromas in the whole study population.
   Dermoscopic
     features                                                                                                    N (61)     %
                        Comedo-like openings                                                                      18       29,5
                        Cerebriform Pattern                                                                       21       34,4
                        Milia-like cysts                                                                          31       50,8
                        Dots                                                                                       3       4,9
                        Irregular Shape                                                                           34       55,7
                        Brown Pseudo-network                                                                      25       41
                        Fingerprint-like Perifollicular structures                                                 5       8,2
                        Glomerular Vessels                                                                        11       18
                        Dotted Vessels                                                                             3       4,9
                        Atypical Vessels (Hairpin, one-looped)                                                    16       26,2
 RCM features                                                                                                    N (11)     %
                        Tumour nest with small cells                                                              11       100
                        Dark round spaces                                                                          6       54,5
                        Well-demarcated borders of the nest                                                        5       45,5
                        Bright structures in the upper dermis                                                      7       63,6
                        Dilated and prominent vessels in upper dermis                                              3       27,3
 Histologic features                                                                                             N (61)     %
                        Lobular growth pattern and broad connection to the overlying epidermis of                 33       54,1
                        poroid cells and cuticular cells, with abundance of melanin (PEPss)
                        Small poroid cells, large and pale cuticular cells with clusters of sebocytes, foci of     2       3,8
                        keratohyaline granules and cystic areas (PPH)
                        Delineated and sharp aggregations of poroid and cuticular cells with tubular              12       19,7
                        structures within the epidermis and an increase in melanin (PHS)
                        Poroid cells and cuticular cells aggregated in small, discrete intradermal nodules        14       23
                        with almost no connection to the epidermis and an increase in melanin (PDDT)

PEP = pigmented eccrine poroma; PHS = pigmented hidroacanthoma simplex; PPH = pigmented poroid hidroadenoma; RCM = reflectance
confocal microscopy.




Original Article | Dermatol Pract Concept. 2024;14(1):e2024088                                                                    3
is more commonly found in non-acral sites [6,7]. Clinically,          the utility of RCM in differentiating them from malignant
PEP can be challenging to distinguish from other pigmented            pigmented lesions, mostly basal cell carcinoma, although no
lesions, including seborrheic keratosis, nevus, histiocytofi-         standardized criteria have ever been described [13,14].
broma, basal cell carcinoma, squamous cell carcinoma and                  Histopathological analysis of PEPs in our case series con-
cutaneous melanoma [8].                                               firmed the characteristic features of this tumor. The tumor
    Our data, which reflect the largest sample of PEPs de-            cells displayed differentiation towards the sweat gland duc-
scribed in the published Literature, provides relevant                tal structures, with the presence of poroid cells, cuticular cells
information concerning the epidemiology, the clinical, der-           and tubular structures. The pigmentation observed in the tu-
moscopic and RCM presentation of PEPs, focusing on their              mor cells was attributed to melanin deposition (Figure 3).
specific features. We aimed to investigate the clinical, dermo-       These histological findings align with previous studies, fur-
scopic and RCM presentation of such tumors, which might               ther supporting the diagnosis of PEP; the differences between
be helpful to guide a correct histopathological diagnosis in          every case show how chameleonic this entity could be, even
difficult cases. Although specific dermoscopic criteria are not       through the lens of dermopathologists (furthermore, some
yet available, certain features might be helpful to better de-        cases of overlapping histological variants are reported in
fine our clinical orientation. Regarding our data, the most
predominant features were irregular shape (N = 34/55.7%),
milia-like cysts (N = 31/50.8%), brown pseudo-network
(N = 25/41%) and comedo-like openings (n = 18/29.5%),
combined with the presence of atypical vessels in about 30%
of cases (Figure 1). These findings partially align with previ-
ous studies that have reported similar dermoscopic patterns
in PEP and consolidate them on a larger scale [6,9-10-12].
The main challenge remains the differential diagnosis with
seborrheic keratosis, which may show similar patterns, as
well as basal cell carcinoma (although in our series, only
a few PEPs displayed blue-brown globules and arborizing
vessels, that may be commonly found in basal cell carcino-
mas) and cutaneous melanoma [8,11,12]. In this sense, RCM
provided valuable insights into the architecture and cellular
features of PEP, giving us the chance to make a correct clin-
ical diagnosis possible. In our series, RCM features included
well-defined tumor nests (N = 11/100%), bright structures
representing melanocytes and melanophages in the upper
dermis (N = 7/63.6%), and dark round spaces within the tu-            ​​​​​​​Figure 2. Reflectance confocal microscopy of pigmented eccrine
mor nests (N = 6/54.5%). The architecture of the lesions was                 poroma showing hypo-refractile dark oval spaces within the tumor
overall symmetric (Figure 2). These findings are consistent                  nests; tumoral bands surrounded by abundant stroma with well de-
with previous reports on RCM features of PEP, emphasizing                    marcated borders.




                                                                      ​​​​​​​Figure 3. Proliferation of pigmented epithelial cells, focal hypergran-
Figure 1. ​​​​​​​Dermoscopic image of pigmented eccrine poroma with          ulosis and melanin deposits in the epidermis. Dilated vessels, focal
milia-like structures, cerebriform pattern and hairpin vessels.              lymphocytic infiltrate, and solar elastosis in the superficial dermis.



4                                                                          Original Article | Dermatol Pract Concept. 2024;14(1):e2024088
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Original Article | Dermatol Pract Concept. 2024;14(1):e2024088                                                                             5
