Akademik Veri Yönetim Sistemi
EURASIAN JOURNAL OF PULMONOLOGY, cilt.10, sa.1, ss.48-53, 2008 (ESCI)
Pulmonary hyalinizing granuloma (PHG) which should be considered in the differential diagnosis of pulmonary nodules of unknown origin is a distinct fibrosing lesion of lung that occurs in middle-aged patients. The radiological appearance of the lesion is that of multiple, bilateral nodules which sometimes mimic metastatic carcinoma. Although the etiopathogenesis of PHG is unknown, it has been postulated that it represents an exaggerated immune response, possibly due to chronic granulomatous infections such as tuberculosis or histoplasmosis or antigen-antibody complexes so that this immune response may result in deposition of immunoglobulins or immune complexes in the lung. PHG has unique histological features. At low magnification, a central area of branching lamellae of hyalinized collagen is surrounded by a more cellular periphery consisting of lymphocytes with germinal centers, plasma cells, histiocytes and spindle-shaped fibroblasts. The pattern of deposition of the lamellar collagen is diagnostic of this lesion and is characterized by thick ropy whorled collagen bundles separated by clear spaces, probably representing a retraction artifact. Most of the patients have a benign clinical course. The clinical, radiological, and histological differential diagnoses include primary and secondary neoplasms, rheumatoid nodule, sarcoidosis, Wegener's granulomatosis, nodular amyloidosis, inflammatory myofibroblastic tumor, infectious chronic granulomatous diseases, intrapulmonary localized fibrous tumor, Hodgkin's lymphoma, nodular sclerosing type, and sclerosing hamartoma. The purpose of this review is to describe distinctive clinicopathological features of PHG, to discuss histological characteristics and differential diagnoses, and to discuss some possibilities regarding its cause and pathogenesis.