Abstract
A 97-year-old man with a previous personal history of multiple nonmelanoma skin cancers presented with a fast-growing, ulcerated reddish nodule on his chest. The nodule was surgically removed, and hematoxylin and eosin stains of the specimen showed an asymmetrical, nonpigmented lesion with architectural and structural impairment, round cells with clear, whitish, foamy cytoplasm, multiple dermal mitoses and nuclear pleomorphism. Our first hypothesis was sebaceous carcinoma, a rare malignant neoplasm derived from epithelial cells showing sebaceous differentiation. A further histopathologic examination showed the presence of pigment in a few areas of the neoplasm. On immunohistochemical study, neoplastic cells were negative for wide-spectrum cytokeratin and diffusely positive for S-100, MART-1, and HMB-45 proteins. Our final diagnosis was nodular malignant melanoma (MM) with balloon epithelioid cells, a "bizarre" presentation of MM in vertical growth phase, mimicking metastatic and primary neoplasms of different lineage derivations.