Electron microscopy and L-dopa reaction in the evaluation of an unusual amelanotic malignant melanoma of the neck.

A 28-year-old white man with a neck mass is described. A diagnosis of amelanotic melanoma was made by L-dopa reaction and electron microscopy. This tumor could represent a metastasis from an unknown primary or a primary that had undergone spontaneous regression. It could also be a rare primary tumor of the cervical sympathetic chain. Electron microscopy and the L-dopa reaction are emphasized as important adjuncts in the diagnoses of amelanotic melanoma.