10.5826/dpc.1301a38
text/xml
2160-9381
2414
en
Harald Kittler
https://creativecommons.org/licenses/by-nc/4.0
Dermatology Practical & Conceptual
melanoma
Basal cell carcinomas presenting as flat pigmented macules on the face mimicking lentigo maligna on dermoscopy: A case series
Text.Serial.Journal
https://dpcj.org/index.php/dpc
Research Letter
2023-01-31
2022-02-22
2023-01-31
2023-02-27
e2023038
Dermatol Pract Concept
Harald Kittler
2023/01/31
10.5826/dpc.1301a38
e2023038
Department of Dermatology, Medical University of Vienna, Vienna, Austria
2160-9381
melanoma
en
e2023038
Tschandl P, Rosendahl C, Kittler H. Dermatoscopy of flat pigmented facial lesions. J Eur Acad Dermatol Venereol. 2015; 29: 120-7.
Basal cell carcinomas presenting as flat pigmented macules on the face mimicking lentigo maligna on dermoscopy: A case series
https://dpcj.org/index.php/dpc/article/download/2414/1906
Basal Cell Carcinomas Presenting as Flat Pigmented
Macules on the Face Mimicking Lentigo Maligna on
            Dermoscopy: A Case Series.
Cristian Navarrete-Dechent1,2, Pablo Uribe1,2, Harold Rabinovitz3, Alvaro Abarzua-Araya1,2,
                                      Harald Kittler4


1 Melanoma and Skin Cancer Unit, Department of Dermatology, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
2 Department of Dermatology, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
3 Department of Dermatology, Medical College of Georgia, Augusta, GA, USA
4 Department of Dermatology, Medical University of Vienna, Vienna, Austria



Key words: dermoscopy, dermatoscopy, basal cell carcinoma, lentigo maligna, melanoma, face
Citation: Navarrete-Dechent C, Uribe P, Rabinovitz H, Abarzua-Araya A, Kittler H. Basal Cell Carcinomas Presenting as Flat Pigmented
Macules on the Face Mimicking Lentigo Maligna on Dermoscopy: A Case Series. Dermatol Pract Concept. 2023;13(1):e2023038. DOI:
https://doi.org/10.5826/dpc.1301a38
Accepted: April 24, 2022; Published: January 2023
Copyright: ©2023 Navarrete-Dechent 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: All authors have contributed significantly to this publication.
Corresponding author: Cristian Navarrete-Dechent, MD, Department of Dermatology, Escuela de Medicina, Pontificia Universidad
Catolica de Chile, Diagonal Paraguay 362, 6th floor, Santiago, Chile 8330077 Phone: +56-2-2435 3574 Email: ctnavarr@gmail.com




Introduction                                                             they were clinically pigmented and flat. Most cases were sub-
                                                                         mitted for biopsy with LM in the differential diagnosis. We
Basal cell carcinoma (BCC), the most common type of skin                 analyzed both pBCC and LM dermoscopic criteria by two
cancer, can usually be diagnosed with dermoscopy with high               independent investigators (CND and HK). A third reviewer
accuracy [1]. We noted, however, that certain pigmented                  helped solving disagreements (PU or .AA). For reflectance
BCCs (pBCCs) are more difficult to diagnose than others.                 confocal microscopy (RCM) images, we used a wide-probe
These challenging pBCCs usually appear as flat, pigmented                RCM (Vivascope 1500). Biopsy reports were obtained from
lesions on the face and mimic lentigo maligna (LM). To bet-              clinical records and reviewed by expert dermatopatholo-
ter characterize these types of pBCCs, we retrospectively                gists. Finally, we analyzed the dermoscopic images with a
collected typical cases of this clinical presentation and re-            previously validated convolutional neural network (CNN)
evaluated the dermoscopic findings.                                      (https://dermonaut.meduniwien.ac.at/ypsono) and recorded
                                                                         the top-1 and top-3 accuracy rates [2].
                                                                              We found 10 cases of BCCs that mimicked LMs. The
Case Presentation
                                                                         mean age at diagnosis was 73 years (range: 44-87 years)
Cases were selected retrospectively from databases from                  and 6 of the 10 patients were females. All BCCs presented
Austria, Chile, and the United States. Cases were included if            as flat pigmented macules on sun-exposed areas of the face


Research Letter | Dermatol Pract Concept. 2023;13(1):e2023038                                                                           1
(Table 1). On dermoscopy, the main feature was a pattern of             cases had pink areas and lacked the typical vascular pattern
angulated lines without obliteration of the follicular open-            of BCC. Shiny white blotches and strands were seen in 4 out
ings, in all cases (Figure 1 and 2). This pattern mimicked              of 10 (40%). One case was examined by RCM and showed
the rhomboidal or ‘zig-zag’ pattern of LM. Additionally, all            classic BCC features such as tumor nodules and cords with



                        Table 1. Demographic and tumor characteristics of included cases.
                Case #          Age (y)            Gender                    Subtype                        Location
               1                    45         F                  Superficial                       Nose
               2                    72         M                  Superficial                       Forehead
               3                    44         F                  Superficial                       Nose
               4                    54         M                  Superficial                       Forehead
               5                    83         M                  Infiltrative                      Cheek
               6                    74         F                  Superficial                       Cheek
               7                    87         F                  Superficial and nodular           Nose
               8                    77         F                  Superficial and nodular           Forehead
               9                    83         F                  Nodular, multifocal               Nose
             10                     42         M                  Superficial                       Cheek
            M = male; F = female.




Figure 1. Basal cell carcinoma presenting as flat pigmented macules. (A) Clinical features of a flat pigmented macule on the nasal supratip.
(B) Dermoscopic features showing rhomboidal structures (arrow) and a pink background (asterisk) (polarized light dermoscopy, original
magnification x10). Inset shows reflectance confocal microscopy features showing tumor nodules with palisading and clefting (original mag-
nification x30). (C) Clinical features of a flat pigmented macule on the right cheek. (D) Dermoscopic features showing rhomboidal structures
(arrow), pink background, and shiny white blotches and strands (asterisk) (polarized light dermoscopy, original magnification x10).



2                                                                           Research Letter | Dermatol Pract Concept. 2023;13(1):e2023038
Figure 2. Basal cell carcinoma presenting as flat pigmented macules. (A) Clinical features of a flat pigmented macule on the right nasal
tip. (B) Dermoscopic features showing rhomboidal structures (black arrow) and a pink background with shiny white blotches and strands
(asterisk) (Polarized light dermoscopy, original magnification x10). (C) Clinical features of a flat pigmented macule on the left nasal tip.
D. Dermoscopic features showing rhomboidal structures (black arrow) and a pink background (asterisk) (Polarized light dermoscopy, orig-
inal magnification x10).




palisading and clefting. With regard to histopathologic sub-            performance of a previously validated CNN underlines that
type, six were superficial, two mixed (superficial and nodu-            these pBCCs are difficult to diagnose [2]. Limitations of this
lar), one had an infiltrative component, and one was nodular            study are (1) that we were not able to estimate the frequency
BCC. The top-1 and top-3 accuracy rates of the CNN were                 of this type of pBCC in clinical practice, (2) that we did not
0% (0 out of 10) and 60% (6 out of 10), respectively. The               include a control group of other flat pigmented lesions such
most common top-1 predictions of the CNN were pigmented                 as pAK or LM, which is the main mimicker, (3) cases were
actinic keratosis (pAK), melanoma, and solar lentigo.                   not consecutive and there might be selection and recall bias,
    The patients in this manuscript have given written in-              (4) no histopathological correlation of the angulated lines in
formed consent to publication of their case details.                    BCCs was available, and (5) no pathology slides review was
                                                                        performed for BCC histopathological subtypes; however, all
                                                                        cases were initially signed by expert dermatopathologists.
Conclusions                                                                 In summary, when evaluating flat pigmented lesions on
                                                                        the face, pBCC should be included in the differential diag-
We characterized a previously undescribed presentation of
                                                                        nosis [4]; especially when seeing angulated lines amidst pink
facial pBCCs mimicking LM. The common confounding fea-
                                                                        areas with or without shiny white blotches and strands.
ture seen in all cases was angulated lines (ie ‘rhomboidal’,
‘zig-zag’) without involvement of hair follicles. Although
all cases were typified by pink structureless areas, none dis-          References
played the typical serpentine and branching vessels of BCC.
                                                                         1. Reiter O, Mimouni I, Gdalevich M, et al. The diagnostic accuracy
In our experience, LM only rarely displays pink areas, which                of dermoscopy for basal cell carcinoma: A systematic review and
could be a clue for the correct diagnosis of BCC. Shiny white               meta-analysis. J Am Acad Dermatol. 2019;;80(5):1380-1388.
blotches and strands also rarely appear on LMs [3]. The poor                DOI: 10.1016/j.jaad.2018.12.026. PMID: 30582991.



Research Letter | Dermatol Pract Concept. 2023;13(1):e2023038                                                                             3
2. Tschandl P, Codella N, Akay BN, et al. Comparison of the accu-         Blotches and Strands With Nonpigmented Basal Cell Carci-
   racy of human readers versus machine-learning algorithms for           noma: E­ valuation of an Additional Dermoscopic Diagnostic
   pigmented skin lesion classification: an open, web-based, inter-      ­Criterion. JAMA Dermatol. 2016;;152(5):546-552. DOI:
   national, diagnostic study. Lancet Oncol. 2019;20(7):938-947.          10.1001/jamadermatol.2015.5731. PMID: 26792406. PMCID:
   DOI: 10.1016/S1470-2045(19)30333-X. PMID: 31201137.                    PMC5037958.
   PMCID: PMC8237239.                                                 4. Tschandl P, Rosendahl C, Kittler H. Dermatoscopy of flat
3. Navarrete-Dechent C, Bajaj S, Marchetti MA, Rabinovitz                 pigmented facial lesions. J Eur Acad Dermatol Venereol.
   H, Dusza SW, Marghoob AA. Association of Shiny White                   2015;29(1):120-127. DOI: 10.1111/jdv.12483. PMID: 24661420.




4                                                                        Research Letter | Dermatol Pract Concept. 2023;13(1):e2023038
