Granulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic antibody (ANCA)-associated disorder with necrotic vasculitis of small- and medium-size arteries and veins. In the literature, there are many case reports of patients with GPA of different, sometimes unusual, clinical manifestations. In this paper, we present difficulties that accompanied the process of diagnosing GPA in a 54-year-old symptomatic patient who was. Computer tomography scans showed numerous tumor-like lesions of various and irregular sizes in both lungs. Positron emission tomography scans suggested a lymphoproliferative disease, otherwise failing to provide a clue concerning its nature or localization. After a series of diagnostic twists and turns, inclusive of bronchoalveolar lavage, cervical mediastinoscopy, paratracheal lymph biopsy, and histopathologic examinations, and other tests, the diagnosis of GPA was established as the most probable. The patient was acutely treated with loading doses of methylprednisolone and cyclophosphamide, gradually tapered off during the long-term follow-up. He was discharged from the hospital in a good condition. We conclude that GPA is an uncommon disease with indistinctive signs, which raises the risk of its being overlooked. A diagnostic algorithm is required for patients with suspected GPA. A timely diagnosis is essential as the disease may quickly progress into renal or multiorgan dysfunction, and ultimately lead to death if untreated. Pulmonary involvement may also suggest neoplastic changes.
Keywords: Antineutrophil cytoplasmic antibody; Granulomatosis with polyangiitis; Lung lesions; Nodules; Vasculitis.