Clinicopathological characteristics of alveolar adenoma

Introduction Alveolar adenoma is an uncommon benign lung tumor that typically appears as a well-defined nodule on imaging and pathological examination. Currently, there is limited research on alveolar adenoma. This article aims to present this rare tumor by describing three cases. Methods We reviewed and analyzed the morphological and immunohistochemical characteristics of three cases using hematoxylin and eosin (HE) staining and immunohistochemistry (IHC). Results The alveolar adenomas exhibited well-defined tumors composed of well-differentiated cuboidal or flattened alveolar epithelial cells that formed glandular or cystic structures of varying sizes, accompanied by well-differentiated spindle cell stroma. Immunohistochemical analysis showed consistently strong and widespread CD34 expression in the stromal cells in all cases. Additionally, CD10 was diffusely positive in stromal cells in about two-thirds of the cases, with focal positivity observed in the remaining case. Discussion While previous research has not identified specific immunohistochemical markers, our findings are interesting, and we suggest that these markers could be useful in diagnosing alveolar adenoma.