Rhabdoid Colorectal Carcinomas: Reports of Two Cases
An 83-year-old woman with a history of hypertension was admitted to Konkuk University Medical Center for the further evaluation of rectal cancer. Colonoscopic examination revealed a huge mass in the rectum. Abdominal, chest CT and PET-CT revealed an ulcerofungating mass in the rectum with multiple metastatic lesions in the liver, lung, perirectal, para-aortic and left common iliac lymph nodes. The serum level of CA19-9 was elevated (60.50 U/mL). Lower anterior resection was performed. The tumor was an ulcerofungating mass, measuring 6.5×4.3×4.0 cm, in the rectum (). Microscopically, the tumor composed of sheets of rhabdoid cells, which comprised 70% of the tumor. The remaining portion of the tumor consisted of gland forming adenocarcinoma cells with villous adenoma. The tumor invaded into the mesosalpinx. Although there was no metastasis in 7 regional lymph nodes, 4 out of 4 omental lymph nodes showed metastases. Adenocarcinoma cells were positive for mixed CK, CK20, and EMA, but focal positive for vimentin (). The rhabdoid tumor cells were positive for mixed CK, but negative for CK20 and EMA. In addition, the rhabdoid tumor cells were diffusely positive for vimentin, but negative for desmin (). E-Cadherin immunoreactivity was attenuated in the adenocarcinoma cells and negative in the rhabdoid tumor cells. Immunohistochemical stains for MLH1, MSH2, MSH6, and PMS2 were positive in both types of tumor cells, while the stains for p53 was negative in the adenocarcinoma cells and focal positive in the rhabdoid tumor cells. Immunohistochemical stains for SMA, CD45, CD99, CD117, synaptophysin, and HMB45 were negative in both types of tumor cells, while the stains for NSE was weakly positive in the rhabdoid tumor cells. Unfortunately, the patient died a month after surgery.