Histopathological Heterogeneity in Pulmonary Hyalinizing Granulomas: A Case Report

Pulmonary hyalinizing granuloma (PHG) is a rare benign lung disease that typically shows slow progression, although some lesions remain stable. We report the case of a 34‐year‐old woman with multiple PHG lesions who underwent two surgical resections at different time points. The histopathological finding of the specimen from the first procedure, a partial resection of the right lower lobe, confirmed PHG with typical hyaline lamellae and mild lymphoid infiltration. Three years later, a right middle lobe lesion showed radiological enlargement and was surgically removed. Although the second specimen also showed histopathological findings consistent with PHG, it contained a markedly increased number of lymphoid follicles, raising concern for a mucosa‐associated lymphoid tissue lymphoma; however, immunohistochemistry and light‐chain analysis confirmed a reactive process. This case indicates inter‐lesional histopathological differences in a single patient with PHG.