Isolated Cerebellar Spindle Cell Pseudotumor Caused by Mycobacterium Avium-Intracellulare Complex in a Patient without AIDS.

BACKGROUND: Spindle cell pseudotumors are formed by histiocytes in response to infection by Mycobacterium avium-intracellulare complex (MAC) and are rare in patients without AIDS. CASE DESCRIPTION: A 66-year-old man presented with neck pain, ataxia, and a history of sarcoidosis. A cerebellar lesion was identified on magnetic resonance imaging and surgically excised. Histopathology revealed this to be a spindle cell pseudotumor and MAC was isolated by bacterial culture of cerebrospinal fluid. Hematology revealed cluster of differentiation 4 lymphocytopenia but human immunodeficiency virus serology was negative. The patient was commenced on antimicrobial treatment that included a macrolide and remained well at 1 year follow-up. CONCLUSIONS: This rare presentation of isolated intracranial MAC was treated with surgical excision and antimicrobials with a good outcome.