Parotid gland malignant melanomas

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.

Retrospective clinicopathologic review of 12 cases of malignant melanoma involving the parotid gland encountered between 1980 and October 1999 at a tertiary referral center.

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.

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.