Abstract

A 45-year-old male immigrant from India presented to the emergency department with a six-week history of cough, fever, chest pain, weight loss, and a progressively enlarging ulcer on the upper back. Initial investigation revealed leukocytosis and an 11 cm cavitary lesion in the left lower lung lobe, prompting the initiation of empiric treatment for tuberculosis with RIPE therapy. However, the patient returned one week later with worsening symptoms, including persistent fevers, transaminitis, hematuria, and hypotension, leading to readmission. Further evaluation showed negative tuberculosis PCR and sputum cultures, with bronchoalveolar lavage revealing rare multinucleated giant cells and an endobronchial biopsy demonstrating acute and chronic inflammation. A dermatology consultation was obtained for evaluation of the ulcer, now measuring 3 cm by 1.5 cm with violaceous, undermined borders. The patient also exhibited gingival petechiae, conjunctival injection, and a petechial eruption on the distal extremities, which rapidly progressed to palpable purpura within 24 hours. Punch biopsies were performed on the ulcer edge and the purpuric rash for routine histology and direct immunofluorescence. Histopathological findings revealed leukocytoclastic vasculitis of the dermal vasculature, with immunofluorescence showing perivascular deposition of C3, and to a lesser extent, IgA, IgM, and fibrin. Given the clinical presentation, a diagnosis of granulomatosis with polyangiitis (GPA) was suspected and confirmed through serological tests, which were positive for anti-proteinase 3 antibodies (PR3-ANCA). The patient was treated with systemic corticosteroids followed by rituximab infusions. This case highlights the essential role of dermatopathology in the diagnosis and management of systemic vasculitis.