Dermatology: Practical and Conceptual Quiz | Dermatol Pract Concept 2016;6(4):12 51 DERMATOLOGY PRACTICAL & CONCEPTUAL www.derm101.com The patient An 87-year-old woman with a history of multiple basal cell carcinomas presented to a follow-up visit referring a pigmented, slowly growing lesion on her right scapula that had been present for one year. Physical examination revealed an irregular 12 x 5 mm well circumscribed pigmented lesion with an elevated keratotic surface (Figure 1). The dermoscopic evaluation revealed a multicomponent pattern: many colors, superior irregular pigmented network with blue-white veil and inferior cerebriform pattern sur- rounded by atypical pigmented network with sharp demarca- tion (Figure 2). The patient underwent complete exeresis of the lesion and the specimen was stained with hematoxylin-eosin. Histo- pathological examination showed a papillomatous epidermal hyperplasia with hyperkeratosis and cell nests in the dermo- epidermal junction (Figure 3) and proliferation of atypical intraepidermal melanocytes with a pagetoid spread (Figure 4). What is your diagnosis? An irregular pigmented lesion on the back Monica Gonzalez-Olivares1, Laura Najera2, Dolores Arias-Palomo1 1 Department of Dermatology, Hospital Universitario de Fuenlabrada, Madrid, Spain 2 Department of Pathology, Hospital Universitario de Fuenlabrada, Madrid, Spain Citation: Gonzalez-Olivares M, Najera L, Arias-Palomo D. An irregular pigmented lesion on the back. Dermatol Pract Concept 2016;6(4):12. doi: 10.5826/dpc.0604a12 Copyright: ©2016 Gonzalez-Olivares et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Corresponding author: Monica Gonzalez-Olivares, MD, Servicio de Dermatología, Hospital Universitario de Fuenlabrada, Camino del Molino 2, 28942 Fuenlabrada, Madrid, Spain. Email: mgonzalezo@salud.madrid.org Figure 1. Close up-view of the scapular area shows an irregularly pigmented lesion with a verrucous surface. [Copyright: ©2016 Gon- zalez-Olivares et al.] Figure 2. Dermoscopic features. Multicomponent pattern. [Copy- right: ©2016 Gonzalez-Olivares et al.] 52 Quiz | Dermatol Pract Concept 2016;6(4):12 to mutations in growth factors more than just a coincidental collision between tumors [2]. These mutations may result in an altered cell-to-cell communication between melanocytes and keratinocytes that would lead to an abnormal prolifera- tion of melanocytes and/or keratinocytes [2]. Taking into account the potential consequences of over- looking a malignant melanoma, thorough clinical and dermo- scopic evaluations should be performed in all patients with seborrheic keratosis in order to provide a correct diagnosis before proceeding to any destructive treatment. References 1. Cascajo CD, Reichel M, Sánchez JL. Malignant neoplasms as- sociated with seborrheic keratoses. An analysis of 54 cases. Am J Dermopathol 1996;18:278-82. PMID: 8806962. 2. Defazio J, Zalaudek I, Busam KJ, Cota C, Marghoob A. Association between melanocytic neoplasms and seborrheic keratosis: more than a coincidental collision? Dermatol Pract Concept 2012;2(2):9. PMID: 23785597. DOI: 10.5826/dpc.0202a09. 3. Salerni G, Alonso C, Gorosito M, Fernandez-Bussy R. Seborrheic keratosis-like melanoma. J Am Acad Dermatol 2015;72:S53-5. PMID: 25500043. DOI: 10.1016/j.jaad.2014.07.009. 4. Thomas I, Kihiczak NI, Rothenberg J, Ahmed S, Schwartz RA. Mela- noma within the seborrheic keratosis. Dermatol Surg 2004;30:559- 61. PMID: 15056152. DOI: 10.1111/j.1524-4725.2004.30178.x. 5. Repertinger S, Wang J, Adickes E, Sarma DP. Melanoma in-situ arising in seborrheic keratosis: a case report. Cases J 2008;1:263-5. PMID: 18947402. DOI: 10.1186/1757-1626-1-263. 6. Jones-Caballero M, Peñas PF, Buezo GF, Fraga J, Aragüés M. Malignant melanoma appearing in a seborrheic keratosis. Br J Der- matol 1995;133:1016-8. PMID: 8547029. DOI: 10.1111/j.1365- 2133.1995.tb06953.x. 7. Yakar JB, Sagi A, Mahler D, Zirkin H. Malignant melanoma appear- ing in seborrheic keratosis. J Dermatol Surg Oncol 1984;10:382-3. PMID: 6232304. Diagnosis Melanoma in situ arising in a seborrheic keratosis Answer and explanation Although previously reported, the presence of a malignant melanoma within a seborrheic keratosis is extremely rare [1,2]. Seborrheic keratoses are common non-melanocytic epidermal tumors that are usually well recognized clinically. Despite this, an accurate diagnosis may be troublesome at times. Dermoscopy is a non-invasive method and diagnostic aid and should be performed in all lesions [3]. In addition to melanocytic nevi, malignant neoplasms arising within or adjacent to seborrheic keratoses have been previously documented [1,2,4-7]. Cascajo et al performed a retrospective analysis of 54 malignant neoplasms in conjunc- tion with seborrheic keratoses, most of them corresponding to basal cell carcinomas, followed in number by squamous cell carcinomas and two malignant melanomas [1]. In addition to the cases reported by Cascajo et al, a handful of cases of mela- noma arising in seborrheic keratoses have been reported in the literature [2,4-7]. This association is believed to be more than a simple coincidental collision between tumors, and the term compound tumor is proposed as the most appropriate appellation [1,2]. A possible explanation is that neoplasms may derive from the different cells that compose seborrheic keratoses: basal cell carcinoma from the predominant basa- loid cells, squamous cell carcinoma from the pale eosinophilic spinous cells and malignant melanoma from the melanocytes admixed among the keratinocytes [1]. Based on previous findings, DeFazio et al postulated that the association of nevus and melanoma with seborrheic keratosis might be due Figure 3. Papillomatous epidermal hyperplasia with hyperkeratosis and cell nests in the dermoepidermal junction. Hematoxylin-eosin- stained section of the specimen (original magnification, 40x). [Copy- right: ©2016 Gonzalez-Olivares et al.] Figure 4. Proliferation of atypical intraepidermal melanocytes with a pagetoid spread. Note large epithelioid cells with nuclear atypia and abundant cytoplasm. Hematoxylin-eosin-stained section of the specimen (original magnification, 200x). [Copyright: ©2016 Gonza- lez-Olivares et al.]