Cutaneous melanoma may in some instances be confused with seborrheic keratosis, which is a very common neoplasia, more often mistaken for actinic keratosis and verruca vulgaris. Melanoma may clinically resemble seborrheic keratosis and should be considered as its possible clinical simulator.  We report a case of melanoma with dermatoscopic characteristics of seborrheic keratosis and emphasize the importance of the dermatoscopy algorithm in differentiating between a melanocytic and a non-melanocytic lesion, of the excisional biopsy for the establishment of the diagnosis of cutaneous tumors, and of the histopathologic examination in all surgically removed samples.</p

Cleide Eiko Ishida

Cíntia Maria Oliveira Lima

Gabriella Campos-do-Carmo

Heloísa Helena Gonçalves de Moura

Marcia Ramos-e-Silva

Maria Luiza Braga Brandão

Tullia Cuzzi

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ACTA DERMATOVENEROLOGICA CROATICADermatoscopic Findings of Seborrheic Keratosis in MelanomaMaria Luiza Brandão1, Cíntia Maria Oliveira Lima1, Heloísa Helena Moura1, Cleide Ishida1, Gabriella Campos-do-Carmo2, Tullia Cuzzi3, Marcia Ramos-e-Silva11Sector of Dermatology, University Hospital and School of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; 2National Institute of Cancer and Sector of Dermatology, University Hospital and School of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; 3Sectorof Pathology, University Hospital and School of Medicine, Federal University of Rio de Janeiro, Rio de Janeiro, BrazilCorresponding author:Prof. Marcia Ramos-e-Silva, MD, PhD Rua Dona Mariana 143 / C-3222280-020 Rio de JaneiroBrazilramos.e.silva@dermato.med.br Received: April 24, 1015Accepted: December 15, 2015144Acta Dermatovenerol Croat                                 2016;24(2):144-147                                      CASE REPORTABSTRACT: Cutaneous melanoma may in some instances be confused with seborrheic keratosis, which is a very common neoplasia, more often mis-taken for actinic keratosis and verruca vulgaris. Melanoma may clinically re-semble seborrheic keratosis and should be considered as its possible clinical simulator.  We report a case of melanoma with dermatoscopic characteristics of seborrheic keratosis and emphasize the importance of the dermatoscopy algorithm in differentiating between a melanocytic and a non-melanocytic lesion, of the excisional biopsy for the establishment of the diagnosis of cu-taneous tumors, and of the histopathologic examination in all surgically re-moved samples.KEY WORDS: seborrheic keratosis, melanoma, dermatoscopyINTRODUCTIONCutaneous melanoma is a sometimes very ag-gressive malignant tumor that may be confused with benign lesions. It must be considered in the clinical differential diagnosis of seborrheic keratosis, which is one of the most common benign neoplasia in adults from the fourth life decade. The vast majority is re-moved by electrosurgery and cryotherapy without histopathologic diagnosis confirmation or may sim-ply not be treated (1,2). Actinic keratosis, verruca vul-garis, and solar lentigines are lesions that are often mistaken for seborrheic keratosis.The objective of this report is to describe a case of melanoma with clinical and dermatoscopic pre-sentation suggestive of seborrheic keratosis, empha-sizing the relevance of the dermatoscopy algorithm for differential diagnosis between melanocytic and non-melanocytic lesions and the importance of exci-sional biopsy in the final interpretation of cutaneous tumoral lesions. CASE REPORTA 67-year-old female patient presented with a heterogeneous plaque on her right arm of 2 cm in the major axis. Colors varied from light brown to black and were asymmetrical, with irregular borders (Fig-ure 1 and Figure 2). The lesion had been present for 3 years, and there had been progressive darkening in the last 2 years. 145ACTA DERMATOVENEROLOGICA CROATICABrandao et al.  Acta Dermatovenerol CroatDermatoscopy of seborrheic keratosis in melanoma   2016;24(2):144-147Multiple comedo-like openings were observed at dermatoscopic examination as well as some milia-like cysts in the darker portion of the lesion, the pres-ence of a peripheral pigmented network resembling a digital impression, and a central bluish-gray area resembling a veil. Despite satisfying several criteria suggestive of seborrheic keratosis, the presence of a pigmented network, asymmetry, and bluish-like veil led to the dermatoscopic interpretation of suspicion of melanocytic lesion instead of seborrheic keratosis (Figure 3).  An incisional biopsy was performed in the most pigmented area of the lesion and, when examining the patient for the second time, the characteristics of the melanocytic lesion were more evident even with-out histopathologic opinion, so excisional biopsy was performed to improve the diagnosis.The histopathology of the incisional biopsy (Fig-ure 4) revealed a melanoma Clark II, Breslow 0.36 mm. The microscopic description included the presence of focal papillomatosis with formation of milia-like cysts, remnants of seborrheic keratosis. The exam of the ex-cisional biopsy only showed the in situ component of the melanoma.DISCUSSIONDermatoscopy is a non-invasive technique that increases the diagnostic accuracy for cutaneous tumors, being especially useful for differentiation between classical clinical melanoma simulators (3). Although dermatoscopic criteria to distinguish me-lanocytic from non-melanocytic lesions have been described, some characteristics may confuse the ex-aminer if present in the same lesion. In fact, several authors have already emphasized the possibility of making a misleading melanoma diagnosis when der-matoscopic features of a non-melanocytic lesion are found in the lesion, such as multiple milia-like cysts and pseudo follicular openings, especially if typical melanoma structures are absent (4,5).Comedo-like openings may be seen in 71% of the lesions of pigmented seborrheic keratosis and milia-like cysts in around 66%. Milia-like cysts and come-do-like openings are considered optimal diagnostic criteria to identify the majority of seborrheic kerato-sis lesions, but the presence of other criteria such as cerebriform fissures, hairpin-like vessels, moth-eaten borders, and a digitiform pattern reduce the risk of diagnostic error, especially in lesions of pigmented seborrheic keratosis. Seborrheic keratosis can also contain structures of a pigmented-type network, Figure 1. Asymmetrical dark brown lesion on the right arm, 2 cm in diameter.Figure 2. Close view of the lesion.Figure 3. Dermatoscopy: comedo-like openings, milia-like cysts, pigmented peripheral network similar to a digital im-pression, and a central blue-grayish area.146 ACTA DERMATOVENEROLOGICA CROATICAwhich however should not be mistaken for the typi-cal pigmented network of melanocytic lesions (6).In a comparative study of dermatoscopic charac-teristics of melanoma (n=37) and those of seborrheic keratosis/solar lentigines on the face, comedo-like openings, milia-like cysts were considered structures associated with benignity because they were not observed in any case of melanoma in the study (7). However, this finding should not be considered as 100% accurate because, on rare occasions, milia-like cysts and pseudo-openings are found in melanoma lesions (7-9).Therefore, melanomas with clinical characteristics of seborrheic keratosis are real diagnostic pitfalls.It is important to note that seborrheic keratosis is an entity of easy clinical diagnosis, usually not requir-ing dermatoscopic evaluation. If the dermatologist needs the dermatoscope to examine a certain lesion, it is probably because that lesion diverges from the customary clinical patterns and deserves attention to eliminate melanoma (5). Care must be taken to exam-ine such suspect lesions following the dermatoscopic algorithm, whose first step is to classify the lesion as melanocytic or not instead of closing the investiga-tion when finding typical structures of a non-melano-cytic lesion, such as the visualization of pseudo cysts and pseudo openings in a seborrheic keratosis-like lesion.It is still unclear in the literature whether sebor-rheic keratosis and melanoma can coincide in the same lesion or if seborrheic keratosis is a forerunner lesion. In fact, seborrheic keratosis lesions are so com-mon that the likelihood of their occurrence concur-rently with melanomas does exist. However, the exis-tence of a carcinogenic factor influencing the growth of both lesions cannot be discarded (4).Occurrence of melanoma within a seborrheic ker-atosis lesion and vice-versa is considered rare; how-ever, the finding of basocellular and Bowen’s disease in seborrheic keratosis lesions is considered more common (10).Cascajo et al. (11) published a retrospective analy-sis of malignant lesions growing in an area adjacent to seborrheic keratosis. Of the 54 lesions studied, 43 basocellular carcinomas were found, 6 cases of Bow-en’s disease, 3 keratoacanthomas, and 2 melanomas. In this study, the term composite tumor was preferred instead of collision tumor, because one cannot affirm if the association between seborrheic keratosis and cutaneous neoplasia is a random event or if there is a pathogenic relation. Other authors, such as Yakaret al., Jones Caballero et al., and Zabel et al. (12-14), pre-fer the term collision tumor since they think there is a greater likelihood of coexistence by accident than due to a pathogenic causal factor.There is a particular variant of melanoma that makes the differential diagnosis between seborrheic keratosis especially difficult: the melanoma type ver-rucous hyperkeratotic, a rare form of melanoma first described in 1967 (15). This variant is similar, both clinically and histopathologically, to seborrheic kera-tosis, and thus capable of inducing a diagnostic error (4,15). Kuehnl-Petzoldt et al. (16) presented a study where 101 patients (9%) had with the diagnosis of verrucous hyperkeratotic melanoma among 1108 pa-tients with melanoma, and Blessings et al. (17) found 20 patients (3.2%) with hyperkeratotic verrucous mel-anoma in 618 melanoma patients. In both studies, approximately 70% of the hyperkeratotic verrucous melanomas were located in the extremities, mainly the legs (4,15).In our case, we were unable to distinguish be-tween the coexistence of seborrheic keratosis and melanoma with superposition of histological findings and the presence of epidermal seborrheic keratosis-like alterations induced by the melanoma. CONCLUSIONWe conclude that the finding of dermatoscopic alterations typical of several entities should not ex-clude the systematic search for elements that indicate the presence of an eventual concurrent melanocytic lesion. Dermatoscopy-histopathology correlation is fundamental as a method for verification of the mul-tidisciplinary interpretative quality.References:1. Stern RS, Boudreaux C, Arndt KA. Diagnostic ac-curacy and appropriateness of care for seborr-heic keratoses: a pilot study of an approach to quality assurance for cutaneous surgery. JAMA 1991;26591:74-7. 2. Chen SC, Bravata DM, Weil E, Olkin I. A comparison of dermatologists’ and primary care physicians’ Figure 4. Focal papillomatosis with formation of milia-like openings, milia-like cysts, in situ component of melanoma (hematoxylin and eosin, ×40).Brandao et al.  Acta Dermatovenerol CroatDermatoscopy of seborrheic keratosis in melanoma   2016;24(2):144-147147ACTA DERMATOVENEROLOGICA CROATICAaccuracy in diagnosing melanoma: a systematic review. Arch Dermatol 2001;137:1627-34. 3. Izikson L, Sober AJ, Mihm MC, Zembowicz A. pre-valence of melanoma clinically resembling se-borrheic keratosis. Arch Dermatol 2002;138:1562-6.4. Carrera C, Segura S, Palou J, Puig S, Segura J, Marti RM, Malvehy J. Seborrheic keratosis-like melanoma with folliculotropism. Arch Dermatol 2007;143:373-6.5. Braga JC, Scope A, Klaz I, Mecca P, Spencer P, Marghoob AA. Melanoma mimicking seborrheic keratosis: an error of perception precluding cor-rect dermoscopic diagnosis. J Am Acad Dermatol 2008;58:875-80.6. Braun RP, Rabinovitz HS, Krischer J, Kreusch J, Oliviero M, Naldi L, et al. Dermoscopy of pig-mented seborrheic keratosis. Arch Dermatol 2002;138:1556-60.7. Schiffner R, Schiffner-Rohe J, Vogt T, Landthaler M, Wlotzke U, Cognetta AB, et al. Improvement of early recognition of lentigo maligna using der-matoscopy. J Am Acad Dermatol 2000;42:25-32.8. Argenziano G, Rossiello L, Scalvenzi M, Staibano S, Ruocco E, Cicale L, et al. Melanoma simulating seborrheic keratosis: a major dermoscopy pitfall. Arch Dermatol 2003;139:389-91.9. Menzies SW, Crotty KA, Ingvar C, McCarthy WH. The diagnostic features of surface microscopy. In: An atlas of surface microscopy of pigmented skin lesions: dermoscopy. 2nd ed. Sydney: McGraw-Hill; 2003:6-52.10. Birnie AJ, Varma S. A dermatoscopically diagnoses collision tumour: malignant melanoma arising within a seborrhoeic keratosis. Clin Exp Dermatol 2008;33:512-3.11. Cascajo CD, Reichel M, Sánchez JL. Malignant neoplasms associated with seborrheic keratoses. An analysis of 54 cases. Am J Dermatopathol. 1996;18:278-82.12. Yakar JB, Sagi A, Mahler D, Zirkin H. Malignant melanoma appearing in seborrhoeic keratosis. J Dermatol Surg Oncol 1984;10:382-3.13. Jones-Caballero M, Peñas PF, Buezo GF, Fraga J, Aragüés M. Malignant melanoma appearing in a seborrhoeic keratois. Br J Dermatol 1995;133:1016-108.14. Zabel RJ, Vinson RP, McCollough ML. Malignant melanoma arising in a seborrheic keratosis. J Am Acad Dermatol 2000;42:831-3.15. Haruna K, Suga Y, Mizuno Y, Ikeda S. Malignant melanoma with a seborrheic keratosis-like clinical presentation. Indian J Dermatol 2009;54:387-8. 16. Kuehnl-Petzoldt C, Berger H, Wiebelt H. Verru-cous-hiperceratotic variations of malignant mela-noma: a clinicopathological study. Am J Dermatol 1982;4:403-10.17. Blessing K, Evans AT, al-Nafussi A. Verrucous nae-void and keratotic malignant melanoma. A clinic-pathological study of 20 cases. Histopathology 1993;23:453-8. Brandao et al.  Acta Dermatovenerol CroatDermatoscopy of seborrheic keratosis in melanoma   2016;24(2):144-147

Dermatoscopic Findings of Seborrheic Keratosis in Melanoma

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