Signet Ring Cell Carcinoma in Urine Cytology: Cytomorphologic Findings and Differential Diagnosis

Background: Signet ring carcinoma is an exceedingly rare and aggressive variant of primary bladder carcinoma. The cytomorphologic features of this rare entity in urinary specimens have not been well characterized. Methods: Twenty-seven cases of signet ring cell carcinoma of the urinary bladder were identified from the pathology archives of The Johns Hopkins Hospital (1989-2011). Of these, 6 cases with prior urinary cytology specimens were studied. Results: There were 5 males and 1 female, with a mean age of 62 years. The presenting complaints included hematuria with or without symptoms of bladder irritation. Histopathologically, there were 5 cases of primary bladder carcinoma and 1 case of metastatic colonic signet ring cell carcinoma. The salient cytomorphologic features included scattered malignant epithelial cells, displaying distinct cell borders, abundant cytoplasm with a single large, discrete mucin vacuole, and eccentric irregular nuclei with prominent nucleoli. Primary adenocarcinoma additionally revealed a few intact malignant glandular epithelial fragments. Metastatic colonic signet ring cell carcinoma displayed predominantly singly dispersed malignant cells with eccentrically placed, oval nuclei with occasional small nucleoli and a moderate amount of vacuolated cytoplasm. Conclusion: Signet ring cell carcinomas are rarely encountered in urinary cytology. The differential diagnosis includes distended histiocytes or degenerated urothelial cells, primary signet ring cell carcinoma, and metastatic adenocarcinoma. Copyright (C) 2012 S. Karger AG, Basel