Primary tiny pure signet-ring cell carcinoma of vermiform appendix presenting as bilateral huge Krukenberg tumors

Primary signet-ring cell carcinoma (SRCC) of vermiform appendix is extremely rare; only three cases have been reported in the English literature. A 52-year-old woman presented with abdominal mass. Physical examination revealed bilateral huge tumors in her ovarian sites. Blood tests demonstrated anemia and elevated tumor markers (CEA, 40 ng/ml; CA125, 580 ng/ml; CA72.4, 1771 U/ml; STN-AG, 19,000 U/ml; sialyl LE, 75 U/ml). Serum AFP, CA19-9, and CA15-3 were within normal limits. Upper and lower gastrointestinal endoscopy revealed no remarkable pathology. CT and MRI showed huge bilateral ovarian solid tumors without clinically apparent other tumors. The clinical diagnosis was primary bilateral ovarian tumors and bilateral oophorectomy was performed. During operation, several quick frozen sections were performed and both ovarian tumors (left: 18 cm, right: 13 cm) were found to be Krukenberg tumors. Accordingly, gynecologists did comprehensive abdominal examination to find out the primary site. They found a small tumor (3 cm × 1 cm) in the distal part of vermiform appendix, frozen sections of which revealed an SRCC. Cytologic evaluation of associated ascites at the operation was positive for carcinoma cells. Then the diagnosis of primary SRCC of appendix with both ovarian metastases (Krukenberg tumors) with peritoneal dissemination was given. Subsequent formalin fixation pathological examination gave the diagnosis. Immunohistochemically, the signet ring cells were positive for cytokeratin (CK) AE1/3, CK CAM5.2, CK8, CK18, CK19, CK20, EMA, CEA, CA19-9, p53, Ki-67 in 50% of tumor cells, CDX2, and MUC2. They were negative for CK34βE1, CK5/6, CK7, CK14, p63, vimentin, TTF-1, MUC1, MUC5AC, MUC6, NSE, synaptophysin, chromogranin, and CD56. She was now treated with chemotherapy 3 months after the operation.