Acquired reversible Brown syndrome caused by focal abscess of the superior oblique muscle

A 16-year-old boy with a history of relapsed acute myeloid leukemia and a right lower lobe lung abscess confirmed to be Aspergillus presented for a baseline eye examination prior to consideration of bone marrow transplantation. He noted double vision in up-and-left gaze, and his examination was consistent with an acquired right-sided Brown syndrome. Magnetic resonance imaging revealed a 4 mm rim-enhancing inflammatory focus in the right superior oblique muscle. His Brown syndrome resolved after treatment with systemic antimicrobials.