Parotid gland malignant melanomas.

BACKGROUND: Malignant melanomas are relatively unusual tumors in the parotid gland. The majority of previously reported cases appear to represent metastatic lesions, often from cutaneous head and neck primaries.
METHODS: Retrospective clinicopathologic review of 12 cases of malignant melanoma involving the parotid gland encountered between 1980 and October 1999 at a tertiary referral center.
RESULTS: Patients consisted of 9 men and 3 women ranging in age from 30 to 84 years (median, 66 years). Eleven of 12 patients presented with a neck mass or nodule. In 9 of 12 patients, a cutaneous or conjunctival primary was noted in the head region. In 2 patients, a cutaneous melanoma and the parotid gland melanoma were diagnosed at the same time. In 1 patient, melanoma was initially diagnosed in the parotid gland, and a definite primary was not uncovered. All patients underwent excision of the parotid melanoma, which was accompanied by a lymph node biopsy or dissection in 10 out of 11 patients. Four patients received adjuvant radiotherapy, and 3 patients received adjuvant chemotherapy. Four of 11 patients had ipsilateral cervical lymph node metastasis at the time of parotid tumor resection, and 5 patients had involvement of intraparotid lymph nodes by metastatic melanoma. Tumors ranged in size from 0.3 to 2.5 cm in greatest dimension. Multiple parotid nodules were noted in 4 patients. All tumors were characterized by a diffuse proliferation of cells with abundant eosinophilic cytoplasm and prominent nucleoli. Four tumors demonstrated focal spindle cell regions. Intravascular and/or lymphatic involvement by tumor within the parotid gland was noted in 3 lesions. At last known follow-up, 6 patients had died with tumor at a median follow-up period of 11 months after parotid gland surgery. Four patients were alive with evidence of tumor at follow-up intervals of 4, 17, 21, and 113 months after parotid gland surgery. Two patients were alive with no evidence of residual tumor at 20 and 148 months of follow-up.
CONCLUSIONS: The majority of melanomas involving the parotid gland appeared to be associated with lymph node metastasis in and around the gland from a cutaneous primary in the head region. Prognosis is generally poor, although rare patients may survive a long period of time following surgery.