Primary melanotic neoplasms of the central nervous system (CNS) are uncommon; amelanotic melanomas in this region are extremely rare. Very few cases of amelanotic variation of primary melanoma in the CNS were reported on. General guidelines or recommendations to establish this diagnosis do not exist.
A sixty-year-old male Hispanic patient presented with a 7-day history of numbness and dizziness. Initial laboratory work-up and physical examination were inconclusive. Cerebral radiological imaging showed a left frontal lesion. Further work-up after clinical deterioration revealed an increase in the lesion size consistent with hemorrhage and changes in T1WI. Biopsy and immunochemistry demonstrated the presence of amelanotic melanoma in the CNS without evidence of another primary lesion.
Primary amelanotic melanoma of the CNS represents a challenge, clinically and diagnostically. Magnetic resonance imaging can be helpful in early stages. Final diagnosis is established with immunohistochemical testing. Physicians should be aware of the existence of this rare manifestation and difficulties faced while building this diagnosis.