Granulomatosis With Polyangiitis Presenting as a Rapidly Enlarging Choroidal Mass: A Case Report.

Granulomatosis with polyangiitis (GPA) is a necrotizing vasculitis that can involve virtually any organ system. Among ocular manifestations, choroidal involvement is exceedingly rare and may mimic intraocular tumors. We report the case of a 68-year-old woman who presented with floaters and a rapidly enlarging choroidal mass. Imaging with contrast-enhanced CT revealed a choroidal lesion, tracheal wall thickening, pulmonary nodules, and maxillary sinus mucosal hypertrophy. FDG-PET demonstrated uptake in these lesions and in the nasal septum. Biopsies of the nasal septum and bronchus showed plasma cell and lymphocyte infiltration with vasculitic changes, providing histopathologic confirmation of vasculitis. Laboratory testing demonstrated elevated CRP and MPO-ANCA positivity. After excluding malignancy, infection, drug-induced vasculitis, and secondary vasculitides, a diagnosis of GPA was made. Oral prednisone (50 mg/day) was initiated, resulting in rapid regression of the choroidal lesion and normalization of MPO-ANCA levels. This case highlights a rare ocular manifestation of GPA presenting as a rapidly enlarging choroidal mass. Awareness of such atypical presentations is crucial to avoid misdiagnosis as intraocular malignancy. Early systemic evaluation and prompt immunosuppressive therapy can lead to rapid resolution and favorable outcomes.