A Rare Case of Squamous Cell Carcinoma of the Colon.

Squamous cell carcinoma (SCC) of the colon is a rare malignancy. Unlike colonic adenocarcinomas, it lacks defined risk factors or established treatment guidelines. We describe a case of metastatic squamous cell carcinoma of the colon in a 77-year-old male with ulcerative colitis. The patient presented with abdominal pain and had labs that revealed transaminitis with conjugated hyperbilirubinemia. Imaging showed a large irregular mixed hyperechoic mass with fluid collection in the liver along with retroperitoneal lymphadenopathy concerning infection/abscess or malignancy. This was initially treated as an infection with broad-spectrum antibiotics and drain placement, but it failed to improve. Biopsy of the liver revealed carcinoma with squamous cell differentiation. In order to look for the primary site, the patient underwent a colonoscopy and esophagogastroduodenoscopy (EGD). EGD was negative, and colonoscopy revealed a mass at the hepatic flexure of the colon with pathology consistent with SCC. PET scan did not reveal any other sites suspicious for primary malignancy. Tempus tumor of origin testing was inconclusive. Hence, colon was thought to be the primary site for SCC with direct extension to the liver. Unlike colonic adenocarcinoma, colonic SCC lacks standardized treatment guidelines. Prognosis is also worse, especially in advanced stages. Surgical resection is preferred for localized disease, but evidence supporting systemic therapy is limited to case reports. The patient was not a surgical candidate and was initiated on FOLFOX (folinic acid, fluorouracil, and oxaliplatin) chemotherapy. This case overall highlights a rare case of colonic SCC and the need for more evidence to guide treatment.