Peritoneal washing cytology of disseminated low grade endometrial stromal sarcoma: a case report

BACKGROUND: Low grade endometrial stromal sarcoma (LESS) with dissemination is rare, and its cytomorphology has not been well described. Recently, we experienced a case of LESS with peritoneal dissemination that was confirmed by peritoneal washing cytology and histology. CASE: A 51-year-old woman was admitted for evaluation of vaginal bleeding. Uterine ultrasonography revealed a diffisely thickened endomyometrium with a vaguely circumscribed nodular mass-like lesion measuring 7.4 cm in the largest dimension. Under the impression of adenomyosis, an exploratory laparotomy was performed. On examination of the abdominal cavity, multiple tiny, grayish nodular excrescences firmly attached to the peritoneal wall and the serosal surface of the small bowel and uterus were noted. A total hysterectomy with bilateral salpingo-oophorectomy and peritoneal fluid sampling were performed. The peritoneal fluid smear demonstrated several loosely packed clusters of monotonous cells showing round to oval nuclei, rare small nucleoli and scanty cytoplasm. CD10 immunostaining revealed cytoplasmic positivity in these cells, but reactive mesothelial cells showed a negative reaction. Histologic examination of the uterus revealed the typical histologic findings of LESS. CONCLUSION: Cytopathologic diagnosis of disseminated LESS is not always easy. Immunocytochemical staining for CD10 can be helpful.