Lung-Limited Seronegative Granulomatosis With Polyangiitis Successfully Diagnosed via a Multi-Disciplinary Diagnosis:...

A 74-year-old man presented with a persistent cough, peripheral blood leukocytosis, and lung opacities. No lesions were identified in the upper airways or kidneys, and the anti-neutrophil cytoplasmic antibodies (ANCA) were negative. The initial clinical presentation was relatively mild and compatible with post-infectious organizing pneumonia; however, the presence of multinucleated giant cells, microabscesses, small granuloma-like lesions, and focal fragmentation/disruption of the vascular elastic laminae, in conjunction with organizing pneumonia in the lung parenchyma, were suggestive of granulomatosis with polyangiitis (GPA). A multi-disciplinary diagnosis, integrating clinical, radiological, and pathological findings, is useful for the early diagnosis of ANCA-negative, lung-limited GPA, which may later recur and require intensive immunosuppressive therapy.