A Unique Presentation of Levamisole-Induced Antineutrophil- Cytoplasmic-Antibody-Positive Vasculitis Presenting as Inflammatory Orbitopathy.

A 35-year-old woman with a history of cocaine abuse presented with progressively worsening OS pain. Neuroimaging revealed a 3-cm ill-defined left orbital lesion involving the intraconal and extraconal spaces. The orbital mass was biopsied via an anterior orbitotomy approach. Pathology demonstrated prominent angiocentric granulomatous and lymphoplasmacytic inflammation consistent with vasculitis. Laboratory tests were significant for neutropenia, positive perinuclear antineutrophil cytoplasmic antibodies with high titer, and positive myeloperoxidase antibodies, consistent with levamisole-induced vasculitis. To the authors' knowledge, this is the first reported case of cocaine-levamisole-induced vasculitis presenting as orbitopathy.