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Basal cell carcinoma and malignant melanoma cutaneous collision tumor.

Malignant tumors composed of both epithelial and melanocytic populations are uncommon. (1,2) Upon reviewing 78,000 excisions of cutaneous tumors, Pierard et al identified only 11 tumors with both basal cell carcinoma and malignant melanoma components. (2) A variety of terms have been applied to these mixed-cell type malignant tumors, including collision, combined, biophenic, and colonized tumors. (3,4) Recently, Satter et al clarified the nomenclature of these subtypes. Collision tumors are defined as two independent neoplasms that occur in close proximity to one another but maintain distinct borders. (4) Accurately categorizing these tumors becomes important for documentation and for increasing knowledge but also for providing prognostic information and properly managing the lesion. Here we present a case of a cutaneous collision tumor of basal cell carcinoma and malignant melanoma.


A 67-year-old man presented to his primary care physician with an ill-defined, variegated plaque on the right dorsal forearm. A biopsy was performed and microscopic examination demonstrated a pigmented basal cell carcinoma. The patient underwent wide excision, yielding a 4.0 x 1.2 x 0.6 cm tissue sample with negative margins. Histologically, nests of basaloid tumor cells were seen with peripheral palisading and focal architectural clefting between the tumor cells and adjacent fibromyxoid stroma. In addition, colonizing the basal cell carcinoma, there was an in situ melanoma composed of large, variably sized nests and single melanocytes. There was also an associated invasive component of melanoma composed of similarly atypical melanocytes (Figures 1a--1c). Immunohistochemical stains for S-100 protein, MART-1, and SOX10 highlighted the melanoma (Figure 1d). Immunohistochemical stains for high-molecular-weight cytokeratin and Ber-EP4 highlighted the basal cell carcinoma. The patient had a negative sentinel lymph node biopsy and has remained free of recurrence for 18 months.


The etiology of the collision between basal cell carcinoma and melanoma remains unknown. Some authors believe that this is a coincidental event, whereas others suspect a field cancerization effect of sun-damaged skin. (1,5) Mancebo et al reported a case in which basal cell carcinoma was thought to be the conduit for the extension of the malignant melanoma cells. (6) These authors also theorized that the increase in cytokines and growth factors secreted from the basal cell carcinoma provides the ideal environment for unchecked melanocytic proliferation. (6) According to Burkhalter and White, the basal cell carcinoma provides the vessel for extension of atypical melanocytes, though this would not be considered true invasion. (7) There have, however, been reports of true invasive melanoma outside of the confines of the coexistent basal cell carcinoma. (8)

(1.) Boyd AS, Rapini RP. Cutaneous collision tumors: an analysis of 69 cases and review of the literature. Am J Dermatopathol. 1994; 16:253-257. doi:10.1097/00000372-199406000-00005. PMID: 7943631.

(2.) Pierard G, Fazaa B, Henry F, Kamoun M, Pierard-Franchimont C. Collision of primary malignant neoplasms on the skin: the connection between malignant melanoma and basal cell carcinoma. Dermatology. 1997; 194:378-379. doi:10.1159/000246154. PMID: 9252769.

(3.) Cornejo KM, Deng AC. Malignant melanoma within squamous cell carcinoma and basal cell carcinoma: is it a combined or collision tumor?--a case report and review of the literature. Am J Dermatopathol. 2013; 35:226-234. doi:10.1097/DAD.0b013e3182545e27. PMID: 22588546.

(4.) Satter EK, Metcalf J, Lountzis N, Elston DM. Tumors composed of malignant epithelial and melanocytic populations: a case series and review of the literature. J Cutan Pathol. 2009; 36:211-219. doi:10.1111/j.16000560.2008.01000.x. PMID: 18727668.

(5.) Miteva M, Herschthal D, Ricotti C, Kerl H, Romanelli P. A rare case of a cutaneous squamomelanocytic tumor: revisiting the histogenesis of combined neoplasms. Am J Dermatopathol. 2009; 31:599-603. doi:10.1097/DAD.0b013e3181a88116. PMID: 19590411.

(6.) Mancebo SE, Marchetti MA, Hollmann TJ, Marghoob AA, Busam KJ, Halpern AC. Melanoma in situ colonizing basal cell carcinoma: a case report and review of the literature. Dermatol Pract Concept. 2015; 5: 25-30. doi:10.5826/dpc.0501a04.

(7.) Burkhalter A, White WL. Malignant melanoma in situ colonizing basal cell carcinoma: a simulator of invasive melanoma. Am J Dermatopathol. 1997; 19:303-307. doi:10.1097/00000372-199706000-00019. PMID: 9185921.

(8.) Belisle A, Gautier M-S, Ghozali F, Plantier F, Wechsler J. A collision tumor involving basal cell carcinoma and lentigo maligna melanoma. Am J Dermatopathol. 2005; 27:319-321. doi:10.1097/ 49026.6a. PMID: 16121053.

Reid Green, MD (a), Meghan Woody, MD, MPH (b), Anthony C. Soldano, MD (a), and Erin Madden, BS (c)

(a) Department of Dermatology, University of Texas at Austin, Austin, Texas; (b) Department of Dermatology, Oregon Health and Science University, Portland, Oregon; department of Nursing, University of San Francisco School of Nursing, San Francisco, California

Corresponding author: Meghan Woody, MD, MPH, Department of Dermatology, Oregon Health and Science University, 3303 SW Bond Avenue, Portland, OR 97239 (e-mail:

Received January 11,2018; Revised February 13,2018; Accepted February 20,2018.

Caption: Figure 1. (a) Low-power (x10) and (b, c) mid-power (x20) hematoxylin and eosin stains showing basal cell carcinoma (black arrows) and melanoma (blue arrow). (d) Positive MART-1 staining within melanoma and absence of staining in basal cell carcinoma.
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Author:Green, Reid; Woody, Meghan; Soldano, Anthony C.; Madden, Erin
Publication:Baylor University Medical Center Proceedings
Article Type:Clinical report
Date:Jul 1, 2018
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