Pulmonary nodules are a frequent anomaly found during chest radiography, and much more so on thoracic computed tomography. Multiple pulmonary nodules are usually caused by prior granulomatous infection or metastatic illness. Multiple pulmonary nodules can also be caused by lymphoproliferative diseases and other unusual ailments such as rheumatoid lung nodules and amyloidosis. Pulmonary hyalinizing granuloma (PHG) is an extremely uncommon disease that may be caused by an immunologic or postinfectious origin. At the histopathologic examination, this condition is characterized by extensive networks of hyalinized collagen bundles organized concentrically around tiny blood vessels. These sclerotic nodules are frequently hypocellular, although they are frequently surrounded by an inflammatory infiltrate, most usually a lymphoplasmacytic infiltration accompanied by histiocytes, fibroblasts, and, in rare cases, eosinophils. PHG can be discovered without symptoms, however, it is frequently linked with nonspecific symptoms. The age range of PHG patients is vast, however, it averages about 43 years. PHG can appear as a single pulmonary nodule, but it is more usually shown as several, bilateral nodules or masses, sometimes quite big, that seldom cavitate or calcify but may increase slowly over time.
The imaging findings are vague, with positron emission tomography detecting hypermetabolism or a lack thereof. Bronchoscopy with transbronchial biopsy or transthoracic core biopsy may occasionally establish the diagnosis of PHG, but these techniques are frequently inconclusive, and surgical lung biopsy is required to confirm the diagnosis. PHG is often indolent in character and has a favorable prognosis.
