Analysis of the clinicopathological characteristics of pulmonary sclerosing pneumocytoma (PSP).

Objective: This study aimed to review the clinical, imaging, pathological, and immunohistochemical features of pulmonary sclerosing pneumocytoma (PSP) and to highlight observations that may help distinguish it from other entities. Methods: This is a retrospective, single-center case series of 22 patients with pathologically confirmed cases of pulmonary sclerosing pneumocytoma (PSP) who underwent surgical resection from January 2022 to August 2025. Clinical records, chest computed tomography (CT) findings, histopathology, immunohistochemistry, surgical treatment, and follow-up data were reviewed descriptively. Result: The results showed that 19 of these 22 patients were female, and the average age was 54.4 years. Typical CT findings were well-defined solid or ground-glass nodules with progressive enhancement and marginal vascular signs. Histologically, the tumors showed two patterns: surface cuboidal cells and round stromal cells grouped in papillary, sclerotic, solid, and hemorrhagic patterns. The pattern of expression of TTF-1 and EMA was diffusely positive in both cell types, while CK7, SPA, and novel aspartic proteinase A (Napsin A) were mainly positive in surface cuboidal cells. Ki-67 expression remained low (1 to 5%). Lung adenocarcinoma was present in three patients. Follow-up was available for no recurrence/metastasis. Conclusion: PSP is a rare tumor of the lung with an indolent behavior, whose imaging and pathological characteristics might help in the differential diagnosis of other pulmonary nodules.