2021 Volume 60 Issue 5 Pages 284-288
Background : Invasive lobular carcinoma sometimes presents cytologically with cells containing intracytoplasmic mucin and having signet ring cell-like features. Metastases from invasive lobular carcinoma may be difficult to distinguish from primary gastric carcinoma. We report a case of invasive lobular carcinoma in which ascitic fluid showed cells with signet ring cell-like features.
Case : A woman in her 50 s, who had undergone surgery for breast cancer at another hospital 4 years earlier, presented to our hospital with a history of abdominal distension. Based on the findings of endoscopy and abdominal CT, the patient was suspected as having type 4 advanced gastric cancer, ascites and carcinomatous peritonitis. Cytologic examination of the ascitic fluid revealed scattered univacuolated signet ring-like cells containing mucin. The atypical cells were small and monomorphic in shape, and showed a high N/C ratio with uniform linear arrays. The cells had thick light-green cytoplasm, increased fine chromatin, and distinct nucleoli, and the diagnosis of poorly differentiated adenocarcinoma was made. The patient was finally diagnosed as having metastasis from lobular carcinoma of the breast to the greater omentum and stomach.
Conclusion : The presence or absence of linear arrays of tumor cells and nuclear pleomorphism, nuclear size, and the ratio of multivacuolated cells among signet ring-like cells in the ascitic fluid are considered to be useful to distinguish invasive lobular carcinoma from poorly differentiated gastric adenocarcinoma.
