The enigma of squamous cell carcinoma of the colon: a case report and review.

Introduction: Primary squamous cell carcinoma (SCC) of the colon is an exceptionally rare malignancy (<1% of colorectal cancers). Its infrequency has limited the development of standardized diagnostic and therapeutic guidelines; most evidence derives from individual case reports. Early recognition is challenging because clinical presentation often mimics more common colorectal tumors. Case Presentation: We describe a 72-year-old woman diagnosed with left-sided (sigmoid) SCC presenting with locally advanced pT4 disease who achieved >12 years of disease-free survival following left hemicolectomy and adjuvant modified FOLFOX-6 chemotherapy. To contextualize this case, we conducted a comprehensive review of 62 published reports meeting strict inclusion criteria. Most patients presented with nonspecific abdominal symptoms. Contrast-enhanced CT(Computed Tomography) and PET/CT (Positron Emission Tomography) were routinely used to define local disease and exclude other squamous primaries. Immunohistochemistry consistently demonstrated positivity for squamous markers (p63, p40, CK5/6) with relative absence of adenocarcinoma-associated markers (CK20, CDX2). Surgery was the primary treatment modality, while systemic chemotherapy was increasingly utilized in stage II-IV disease. Conclusion: Adjuvant chemotherapy may benefit select high-risk stage II patients with primary colonic SCC with high-risk features such as pT4 tumor penetration. as exemplified in this case. Consistent data collection, collaboration, and molecular characterization are essential to establish evidence-based treatment strategies for this uncommon malignancy.