Clinical and pathologic distinction between primary and metastatic mucosal melanoma of the head and neck.

Metastatic mucosal melanoma is extremely rare. Only 0.6% to 9.3% of patients with cutaneous malignant melanoma will have metastases to the mucosa of the upper aerodigestive tract. The records of all patients with mucosal melanoma of the head and neck at the University of California, Los Angeles Medical Center during the past 30 years were reviewed. Patients with primary tumors were separated form those with metastatic involvement from a cutaneous primary site. These two groups were compared for differences in clinical symptoms, histopathologic findings, treatment, and survival characteristics. Frequent sites of metastatic involvement included the base of tongue and nasal cavity. These arose from a variety of cutaneous sites including the trunk and extremities and, in most instances, did not arise until 2 to 7 years after the initial cutaneous lesion. Most of those with metastases to the head and neck mucosa had disseminated disease. The histopathologic distinction between the two groups is described with photomicrographs. Junctional activity in the overlying or adjacent mucosa distinguishes primary mucosal melanoma from metastatic disease, in which the overlying mucosa is usually intact. This difference is useful in determining workup and treatment options. Aggressive surgical resection is suggested in treatment of primary melanomas, whereas surgery is at best palliative in those with metastatic disease.