Seronegative Granulomatosis With Polyangiitis With Isolated Lung Lesions: A Case Report

Granulomatosis with polyangiitis (GPA), previously referred to as Wegener's granulomatosis, is an uncommon form of necrotizing vasculitis that predominantly targets small and medium-sized blood vessels as a result of granulomatous inflammation. Granulomatosis with polyangiitis is defined by the existence of necrotizing granulomas in the upper respiratory tract, along with renal involvement, which includes necrotizing glomerulonephritis with extra capillary crescents. From a diagnostic perspective, there is a high correlation between GPA and proteinase-3 anti-neutrophil cytoplasmic antibody (PR3-ANCA) because of the release of inflammatory cytokines, reactive oxygen species (ROS), and lytic enzymes. While ANCA-positive serology is commonly used as the diagnostic criteria, we present a seronegative GPA case with isolated lung lesions. A 54-year-old woman was referred for an assessment of hemoptysis and alterations in her chest radiograph. The patient's laboratory results showed a positive QuantiFERON test but negative results for ANCA and antinuclear antibodies (ANA) tests. A chest CT scan showed the presence of several pulmonary nodules in both lungs, with some cavitation. A CT-guided biopsy was conducted on a nodule located in the lower lobe of the right lung. The results showed that the nodule had non-neoplastic chronic inflammation and an area of geographic necrosis. A second robotic-assisted left upper and lower lobe wedge resection was done, which showed white to tan granular lesions with necrotizing granulomatous inflammation and lymph nodes with anthracosis and a lot of histiocytes, which is typical of GPA. The patient received a six-month course of intravenous rituximab treatment.