Abstract
Background : We present a rare case of pulmonary PEComa, which showed characteristic cytologic appearances on imprint cytology.
Case : Computed tomographic examination revealed a pulmonary nodule in a 43-year-old male with liver tumors suspected to be metastatic carcinomas from a primary tumor of unknown origin. The lesion was suspected to be a primary pulmonary carcinoma and was resected by video-assisted thoracoscopic pulmonary segmentectomy. Imprint cytologic smears obtained from the resected specimen revealed cuboidal to round, uniform, and small tumor cells with abundant, clear and/or foamy cytoplasm. The cells had round to oval and small nuclei, and showed no conspicuous atypia. Occasionally, spindle-shaped tumor cells with spindle-shaped nuclei were also observed. Intranuclear inclusions were frequently observed. No mitoses were seen. On immunohistochemistry, the tumor cells showed positive staining for HMB-45. The imprint cytology findings suggested the possibility of PEComa. Histologically, the nodule was diagnosed as a PEComa, and on immunohistochemistry, the tumor cells were positive for HMB-45.
Conclusion : Findings such as abundant clear cytoplasm, lack of conspicuous cellular and nuclear atypia, admixture of spindle-shaped cells, and presence of nuclear inclusions are helpful for making a correct diagnosis of PEComa.
