Neurotropic melanoma. A case report and review of the literature.
Neurotropic melanoma is a rare tumor with a biphasic growth pattern associated with a change in morphology from melanocytic features toward Schwann cell features. The tumor thereby develops a capacity for infiltrating nerves which may result in clinically evident cranial neuropathies, most commonly of the fifth and seventh cranial nerves. The histology of this lesion is difficult to interpret; it often erroneously appears fibrous in origin and may be considered to be benign. Despite this benign appearance histologically, the tumor behaves aggressively with multiple local recurrences and possible CNS invasion by either direct perineural growth or distant metastases. We review the literature of neurotropic melanomas and report a 46th case which describes a typical course with neural invasion. Although a rare cause of cranial neuropathies, the neurologist should consider this entity in the differential diagnosis and the history of a recurrent skin lesion of the face should be sought whenever examining such a patient.