A case of CD8+ T cell lymphoma occurring during treatment for in situ malignant melanoma of the palate.

A 53-year-old Japanese male noticed pigmented lesions on his right upper gingiva and hard palate in February of 1986. Histological examination revealed in situ malignant melanoma. Chemotherapy, beta-interferon, and oral BCG were given. However, tumors subsequently developed in the nasal cavity in March of 1989. The patient died in April of 1990 after developing Garcin's syndrome and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Autopsy revealed aggressively infiltrating, whitish tumor masses invading the hard palate, the nasal cavity, the paranasal sinuses, the base of the skull, cranial nerves I-X, and the pituitary body, as well as severe necrosis of the soft palate. However, there was no evidence of malignant melanoma. Instead, these oval tumor cells had atypical nuclei and scanty cytoplasm. They contained no melanin granules, were negative for S-100 protein, and were also negative for various melanoma-associated antigens. They were positive for CD2, CD3, and CD8 by avidin-biotin-peroxidase complex immunohistochemistry. It was concluded that the patient had CD8+ non-Hodgkin's malignant lymphoma (diffuse, large cell type) of the nasopharyngeal region, which was preceded by in situ malignant melanoma of the palate.