CDX2-positive Cancer of Unknown Primary With Upper-body Paralysis Was Dramatically Improved by Colorectal Cancer Chemotherapy

Abstract

Background: Caudal-related homeobox transcription factor 2 (CDX2) is expressed in intestinal epithelial cells. CDX2 is a very sensitive marker for the identification of small and large intestine tumors, which is expressed in 85.7-100% of colorectal cancer (CRC) cases. Case Report: A 61-year-old female had been suffering from left shoulder pain for one month. Computed tomography showed osteolytic masses extending to the vertebral arch in the C5, C6, C7, and Th3 vertebral bodies. In addition, a thickening of the sigmoid colon was observed from the rectal-sigmoid colon, suggesting CRC. A colon biopsy revealed poorly differentiated adenocarcinoma and the vertebra excision was metastatic adenocarcinoma. However, immunohistochemically, the vertebra tumor was negative for CK7 and CK20 but positive for CDX2. Therefore, we made the diagnosis of CRC with bone metastasis and decided to start treatment for CRC. Posterior stabilization was performed for the spinal tumor 6 days after admission. About one month after admission, she started treatment with chemotherapy. Initially, her left hand could not move, and she could barely hold the pen with her right hand. After adding cetuximab for the third time, she became able to bend the dorsiflexion of her right wrist joint, grasp a stick with her right hand, and move the fingertips of her left hand a little. Conclusion: The presented case could not be diagnosed as CRC unless CDX2 was examined. Upper body paralysis due to CRC bone metastasis was improved by chemotherapy.