Five years after gastrectomy, cytological examination of the ascites revealed tumor cells positive for GATA3 and estrogen receptor, and negative for E-cadherin, leading to a diagnosis of peritoneal metastasis from breast cancer.ILC is characterized by a loss of E-cadherin and diffuse metastatic patterns, including peritoneal and gastric involvement. The gene discussed is ESR1; the disease is neoplasm.