Primary malignant melanoma of the oral cavity. Case report and establishment of melanoma cell line.

Malignant melanomas rarely grow in the oral mucosa and few established melanoma cell lines originate from the gingiva. Our patient was a 59-year-old man with a dark mass at the upper incisive gingiva and a large lymphadenopathy in the submandibular region. The gingival biopsy showed malignant melanoma. Because of the marked metastases, he received both chemotherapy and immunotherapy. Although regression and discoloration of the tumors were seen, he died of respiratory failure 9 months after admission. At autopsy, metastatic amelanotic and melanotic melanomas were found in various organs. Cells were obtained for tissue culture from pleural fluids of the patient. Eagle's MEM or RPMI1640 with 20% f.c.s. was used for the culture medium, and cells were found to attach to the bottom of the culture tube and to show no contact inhibition. Electron microscopy of primary cultured cells showed premelanosomes in the cytoplasm. The cells were transplantated into nude mice for studies of tumorgenesis and for serial transplantation of the tumor. A progressive tumor appeared. At present (June 19, 1980), 110 passages have been made and the cells are growing well. They were named HMG.