Isolated Sensorineural Hearing Loss as the Sole Manifestation of Granulomatosis with Polyangiitis

BACKGROUND Granulomatosis with polyangiitis (GPA) is a rare systemic vasculitis of small vessels associated with anti-neutrophil cytoplasmic antibodies (ANCA), typically affecting the respiratory tract and kidneys. Otologic involvement is relatively common, yet sensorineural hearing loss (SNHL) as the initial and sole clinical manifestation is exceptionally rare. Most reported cases of isolated SNHL in GPA involve unilateral or fluctuating hearing loss. Progressive bilateral SNHL associated with positivity for ANCA targeting proteinase 3 (PR3-ANCA), in the absence of systemic or ocular involvement, is rarely described in the literature. CASE REPORT A 36-year-old man with no significant medical history presented with sudden-onset left-sided SNHL, which was partially responsive to oral corticosteroids. Four weeks later, he developed bilateral hearing loss, tinnitus, aural fullness, and non-disabling postural instability. Audiometry revealed moderate-to-profound bilateral SNHL. Infectious and hematologic causes were ruled out. Laboratory tests showed positive PR3-ANCA, negative antinuclear antibodies (ANA), and mildly elevated inflammatory markers, including an erythrocyte sedimentation rate of 31 mm/h and a C-reactive protein level of 9.6 mg/dL. Head MRI was unremarkable, and no ocular, nasal, pulmonary, or renal involvement was found. A diagnosis of GPA with isolated inner ear involvement was made. Treatment with corticosteroids and rituximab led to symptom stabilization. CONCLUSIONS This case highlights an unusual presentation of GPA with PR3-ANCA positivity and progressive bilateral SNHL as the sole manifestation. Early recognition of atypical GPA presentations is essential to prevent irreversible hearing loss. Clinicians should consider ANCA-associated vasculitis in patients with unexplained bilateral SNHL, even in the absence of systemic signs. Early immunosuppressive therapy may preserve auditory function.