A Rare Case of Granulomatosis With Polyangiitis With Cutaneous Pyoderma Gangrenosum-Like Lesions of the Bilateral Parotid Glands.

Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis, is a small vessel vasculitis characterized by necrotizing granulomas affecting various organs. This case report presents a 79-year-old male with GPA manifesting as pyoderma gangrenosum-like cutaneous lesions involving the bilateral parotid glands. The patient presented with painful, progressively-enlarging wounds that were affecting his quality of life. The initial workup was inconclusive, and the patient was briefly lost to follow-up. Upon return, the lesions had progressed to salivary fistulas, and the patient exhibited facial nerve weakness. Chest radiographs revealed worsening lung densities. A punch biopsy indicated granulomatous inflammation with necrosis, and autoimmune lab work showed elevated antinuclear antibody, erythrocyte sedimentation rate, C-reactive protein, and cytoplasmic antineutrophilic cytoplasmic antibodies levels. The patient was diagnosed with GPA and started on Rituximab therapy. The patient responded well to therapy and had resolution of ulcerations and facial nerve weakness. This case is a rare presentation of GPA affecting bilateral parotid glands with involvement of the facial nerve. It underscores the importance of considering GPA in the differential diagnosis of necrotic skin lesions and highlights the challenges in diagnosing GPA due to nonspecific histologic findings and wide variation of clinical presentation.