Cytokeratin 7-positive/cytokeratin 20-negative cecal adenocarcinoma metastatic to the uterine cervix: a case report

BACKGROUND The vast majority of uterine cervical malignancies are primary carcinomas, and secondary neoplasms that metastasize to the uterine cervix from a distant organ are uncommon. Although relatively rare, metastases to the uterine cervix from a primary colon cancer have been reported. We report a rare case of metastatic carcinoma originating from a cecal adenocarcinoma with an unusual cytokeratin 7/cytokeratin 20 immunophenotype. CASE PRESENTATION A 74-year-old postmenopausal Japanese woman was referred to our hospital for the evaluation of a uterine tumor. She had a past medical history of cecal cancer and had undergone laparoscopically assisted right hemicolectomy at the age of 69 years. During follow-up, she was found to have elevated levels of the tumor markers carbohydrate antigen 19-9 (179.7 IU/mL) and carcinoembryonic antigen (26.9 μg/L). Positron emission tomography/computed tomography showed a focus of high 18F-fluorodeoxyglucose uptake in her uterus. Examination of a cervical biopsy found a poorly differentiated adenocarcinoma that was immunopositive for cytokeratin (CK)7 and caudal-related homeobox 2 (CDX2) expression and immunonegative for cytokeratin 20 expression. The patient underwent radical hysterectomy and bilateral salpingo-oophorectomy. Histopathological examination found invasive growth of irregular and atypical ductal hyperplasia. Immunohistochemical staining of the tumor specimen revealed the same immunophenotype as the biopsy specimen. The cecal cancer specimen from her previous surgery was also examined and found to have the same immunophenotype. The histopathological diagnosis was cecal adenocarcinoma metastatic to the uterine cervix. The patient is currently receiving adjuvant chemotherapy and to date is without evidence of recurrent disease. CONCLUSIONS Our report illustrates the importance of immunohistochemistry for the correct diagnosis of the origin of a uterine cervical adenocarcinoma in a patient with a medical history of colorectal cancer. Re-examination of a previous oncological specimen is critical for cases with a uterine lesion that is difficult to identify as primary or metastatic cancer.