2018 Volume 67 Issue 5 Pages 802-808
Background: Peritoneal metastasis secondary to breast carcinoma is rare. In effusion cytology, cell block (CB) immunocytochemistry is useful for determining the primary sites of metastatic adenocarcinomas in ascites fluid. Herein, we report two cases of breast carcinoma with peritoneal metastasis diagnosed by ascites cytology. Case 1: A 40-year-old woman underwent left total mastectomy for invasive ductal carcinoma. Two years and ten months later, abdominal computed tomography demonstrated massive ascites. Ascites fluid cytology showed isolated neoplastic cells with eccentrically located atypical nuclei and intracellular mucin, consistent with poorly differentiated adenocarcinoma. CB immunocytochemistry of ascetic fluid showed that the tumor cells were positive for GATA3, GCDFP15, and E-cadherin, but negative for ERα and PgR, confirming a diagnosis of peritoneal metastasis of invasive ductal carcinoma of the left breast. Case 2: A 50-year-old woman was previously diagnosed as having an invasive lobular carcinoma of the left breast and was treated by left total mastectomy. One year and seven months later, imaging findings revealed ascites and a cytology test was performed. In ascites cytology specimens, atypical cells forming loosely cohesive small clusters had enlarged nuclei and showed an intracytoplasmic lumen. CB immunocytochemistry of ascites fluid showed immunoreactivity for GATA3, ERα, and CA15-3, but immunonegativity for carletinin in atypical cells. A diagnosis of peritoneal metastasis from invasive lobular carcinoma of the left breast was made. Conclusion: CB immunocytochemistry in conjunction with conventional cytological smearing is useful for the cytological diagnosis of breast cancer cells in ascites.
