A Comparative Study of Intraoperative Cytology and Frozen Sections of Sclerosing Pneumocytoma

Sclerosing pneumocytoma (SP) is a rare benign neoplasm of the lung. Conservative surgical excision is curative with an excellent prognosis. Preoperative diagnosis of SP can be difficult. Thus, intraoperative frozen sections play a crucial role in guiding surgical management. However, the interpretation of frozen section can be challenging due to freezing artifact. Intraoperative cytology provides a complementary and better morphological detail. In this study, we review and compare the intraoperative cytology and frozen section of 14 cases of SP. SP is characterized by containing 2 cell types: round stromal cells and cuboidal surface cells. The round stromal cells were small with uniform nuclei and inconspicuous nucleoli. The cuboidal surface cells were more differentiated into type II pneumocytes and showed slightly larger in size with intranuclear inclusions. The immunocytochemical double-labeling staining could display 2 distinct population of vimentin-positive round stromal cells and cytokeratin 7-positive cuboidal surface cells. Recognition of the cytological features of SP circumvents the frozen section artifact and is a useful adjunct to the frozen section in leading to the correct diagnosis of SP.