Cystic pulmonary metastases of endometrial stromal sarcoma of the uterus, mimicking lymphangiomyomatosis: A case report with immunohistochemistry of HMB45

A case of endometrial stromal sarcoma (ESS) showed cystic pulmonary metastases mimicking lymphangiomyomatosis (LAM). A 58-year-old female, who had undergone total hysterectomy for low-grade ESS 16 years previously, had repeated bouts of pneumothorax. Multiple then-walled cysts in the perlpheral lung were revealed by radiological examinations. In an open-lung blopsy specimen, cystlc lesions were surrounded by layers of spindle-shaped cells of varying thickness that resembled LAM. However, In addltion to subtle histological differences from LAM, HMB45 (antimelanoma antibody) showed positive In LAM (n=3), but was negative in ESS (M) and the cystlc leslons of this case. Using myogenic markers (desmin and α-smooth muscle actin), metastatlc ESS could be immunohistochemically differentiated from mesenchymal cystlc hamartoma (n=1). HMB45 Immunohistochemistry is useful in the differential diagnosis of cystic puimonary lesions.