Clear cell adenocarcinoma of colorectum: a case report and review of the literature.

Primary clear cell adenocarcinoma of the colorectum is a rare neoplasm, which differs from ordinary carcinomas of the colorectum in morphological features, but shares some traits of clear cell carcinoma of other organs. The tumor is usually composed of polygonal or oval cells with abundant granular and clear cytoplasm. The nuclei are often in hyperchromatic shapes with vesicular nucleoli. We report the first case of clear cell adenocarcinoma of the colorectum in China and review the related published cases. The tumor was located in descending colon of a 37-year-old man, and was rich in glycogen but poor in mucin. By immunoperoxidase and histochemical staining, we clarified the clinicopathological characteristics, diagnosis and differential diagnoses, and pursued its potential pathogenesis. In our case, necrosis, high mitotic activity and lymph node metastasis may suggest a highly malignant tumor and an advanced pathological stage. Nevertheless, the patient has survived for one year with the help of operation and postoperative adjuvant chemotherapy. Regardless of the stage and differentiation, surgical therapy and proper adjuvant chemotherapy are effective means to treat the clear cell adenocarcinoma of the colorectum.