On gross examination, the tumor was nodular, ulcerated, and at least 4 cm thick. Histologically, there was a well-developed junctional melanocytic proliferation. The melanocytes also showed confluent dermal growth, a lack of maturation, and prominent cytlogic atypia, with anisonucleosis and large nucleoli. Abundant mitotic figures were present throughout the lesion. Several areas of identifiable melanin pigment were seen in the routine sections. Immunohistochemical staining was markedly and diffusely positive for S100 protein and HMB-45. In summary, these features were thought to be consistent with a primary melanoma.
Giant Tumor of the Back. Arch Dermatol. 2002;138(9):1245-1250. doi:10.1001/archderm.138.9.1245