2016 Volume 55 Issue 1 Pages 32-38
Background : We have experienced a case of invasive lobular carcinoma of the signet-ring-cell type, and we report herein on the cytological findings and intracytoplasmic mucin.
Case : A female in her fifties consulted with a mass which had been discovered. The fine-needle aspiration (FNA) cytology revealed dissociated tumor cells with signet-ring-cell appearance including orange mucin. Histologically, small tumor cells grew in a linear manner together with a targetoid distribution. Approximately 20% of the tumor cells were recognized as signet-ring-cells which were strongly positive for PAS. Immunohistochemically, E-cadherin was negative and p120 was diffusely positive, so that the tumor comprised a lobular carcinoma with a component containing signet-ring-cell carcinoma. In the component of the classical type lobular carcinoma, the surrounding cell membranes were positive for MUC1. On the other hand, signet-ring-cell carcinoma component, not only were the cell membranes positive for MUC1, but the intracytoplasmic mucin also tested positive. Eighty percent of intracytoplasmic mucin was positive for GCDFP-15. MUC2, MUC5AC and MUC6 were negative in both types of cell.
Conclusions : Invasive lobular carcinoma of the signet-ring-cell type shows characteristic cytological features. MUC1 and GCDFP-15 showed positive for intracytoplasmic mucin whereas MUC2, MUC5AC and MUC6 were negative.
