Which histologic findings are characteristic of head and neck mucosal melanomas?

Updated: May 07, 2020
  • Author: Neeraj N Mathur, MBBS, MS, DNB(ENT), MNAMS, FAMS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

The presence of a pigmented lesion in the oral or nasal cavities should raise suspicion of mucosal melanoma, and a biopsy of the lesion should be promptly obtained. Diagnosis of pathologic disease is dependent on the identification of intracellular melanin. With a fresh tissue sample, dopa-positive melanocytes can be identified using the dopa reaction to demonstrate tyrosinase activity. Nonetheless, immunohistochemistry is often required to diagnose malignant melanoma, because only 50-70% of lesions in the oral cavity demonstrate melanin.

Microscopically, 2 histologic patterns can be described, an in situ pattern in which the neoplasm is limited to the epithelium and the epithelial-connective tissue interface, and an invasive pattern in which the neoplasm is found within the supporting connective tissue. [6] A combined pattern is usually typical of most advanced lesions. Several different cell types comprise the tumor. Spindled, plasmacytoid, and epithelioid tumor cells arranged in a sheetlike, organoid/alveolar, neurotropic, or desmoplastic configuration may be observed. Melanin pigment is noted in almost 90% of lesions.


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