An unexpected primary squamous cell carcinoma of the left colon: a rare case report

Colorectal cancer is a common cancer with a large burden of disease. Adenocarcinomas account for majority of colorectal cancers, arising from glandular epithelium. Other malignancies including neuroendocrine, adenosquamous, spindle cell and squamous cell carcinomas (SCCs) are seldomly encountered. Primary colorectal SCC was first reported in 1919 and is particularly rare. It is difficult to manage as patients present late, with locally invasive or metastatic disease. We present the case of a woman in her 40s with a previously resected sigmoid adenocarcinoma and a new splenic flexure mass. Histopathology revealed an SCC without evidence of extra-colonic disease. The patient underwent resection with clear margins, however, did not tolerate systemic adjuvant treatment and developed local recurrence within twelve months. We add our patient's case to the small compilation of cases of primary colorectal SCC along with a summary of its clinical and histological characteristics, strategies in management and considerations for future research.