Sections of the biopsy specimen showed a large, well-circumscribed tumor nodule extending from the reticular dermis to the subcutaneous fat. Connection with the overlying acanthotic epidermis was not identified. The centrally necrotic tumor was composed of nests and cords of highly pleomorphic, poorly differentiated cells with abundant clear to eosinophilic cytoplasm and numerous mitotic figures. Rare gland formation was noted. The tumor stained positively for mucicarmine, cytokeratin, and carcinoembryonic antigen and negatively for vimentin, HMB-45, and S100 protein. The histologic features and staining profile supported the diagnosis of a metastatic poorly differentiated adenocarcinoma, consistent microscopically with the microscopic appearance of the patient's lung cancer.
Rapidly Enlarging, Violaceous Nodule on the Abdomen. Arch Dermatol. 2001;137(4):495-500. doi: