[Pulmonary hyalinizing granuloma. Clinicopathologic study of 2 cases, with some original ultrastructural observations and review of the literature].

AIM: To report the clinical, histological, immunohistochemical and ultrastructural features of 2 new cases of pulmonary hyalinizing granuloma. RESULTS: Both patients were males: one, 72-year-old with retroperitoneal fibrosis, was asymptomatic, while the other, 67-year-old, presented with non productive cough. In both cases, a chest x-ray showed a solitary pulmonary nodule. Microscopically, the nodules were well circumscribed and composed of lamellae of hyalinized collagen. At the periphery, a more cellular rim consisting of lymphocytes, plasma cells and myofibroblasts was present. Immunohistochemical and ultrastructural examinations revealed myofibroblastic elements actively synthesizing collagen fibrils.