Carcinosarcoma of the colon with extensive and extraordinary metastases detected on F-FDG18PET/CT: A case report

INTRODUCTION: Sarcomatoid carcinomas or carcinosarcomas are rare tumors with a double component, carcinomatous and sarcomatous. They most commonly arise from the head, neck, respiratory system and female genital tract. To the best of our knowledge, only thirty two cases of colorectal involvement have been reported in the medical litterature. CASE REPORT: We report a case of sarcomatoid carcinoma of the colon in a 58 year old woman with unusual sites of metastasis revealed by a whole body 18F-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), who presented with right iliac fossa pain. Physical examination revealed only tenderness of the right iliac fossa. A right hemi-colectomy was performed. The immunohistochemical study of the surgical specimen revealed 2 cellular contingents, one carcinomatous and the other sarcomatous, leading to the diagnosis of carcinosarcoma. The evolution was rapidly unfavourable, with death occurring 4 months after the initial surgery. DISCUSSION: Colorectal carcinosarcomas are very rare and aggressive tumors with high metastatic potential commonly in the liver, lymph nodes, and peritoneum. In our case, we order a FDG-PET/CT that revealed intriguing pattern of metastasis. CONCLUSION: The purpose of presenting this case report is to raise awareness among clinicians to consider this clinical entity as a differential diagnosis of colorectal tumors and order more often FDG-PET/CT for a good clinical staging.