S1841 Colorectal Squamous Cell Carcinoma: An Usual Presentation of an Unusual Cancer

Abstract

Introduction: Squamous cell carcinoma (SCC) is an extremely rare cause of colorectal malignancy and makes up to 0.025% of all colorectal malignancies. Clinically, it presents with similar signs and symptoms as colorectal adenocarcinoma. Due to the rarity of this pathology, there is limited information on optimal treatment and disease prognosis, making early identification with a diagnostic colonoscopy and biopsies essential. Here, we present a rare case of colorectal SCC in the hepatic flexure with local invasion to the gallbladder and liver in a patient with chronic abdominal discomfort. Case description/methods: A 54-year-old female with hypertension and diabetes mellitus presented to the clinic complaining of abdominal discomfort for one year. She denied hematochezia, melena, hematemesis, weight loss, and changes to her bowel habits. Abdominal examination demonstrated epigastric and right upper quadrant tenderness. Initial routine laboratory studies were unremarkable. Ultrasound of the abdomen showed a right hepatic lesion which was confirmed on follow up CT scan of the abdomen that demonstrated a 7.1 × 6.7 × 7.6 cm heterogeneous mass in the transverse colon, inseparable from the gallbladder and left hepatic lobe. A subsequent MRI of the abdomen demonstrated consistent findings. Analysis of tumor markers demonstrated elevated carcinoembryonic antigen at 69.4 ng/mL (reference range: ≤5.0 ng/mL). Whereas, alpha-fetoprotein and cancer antigen 19-9 were negative. The patient also tested negative for Hepatitis C, HIV, and HPV and was found to be non-immune to Hepatitis B. Considering a high suspicion for malignancy, a diagnostic colonoscopy was performed which revealed a 5 cm polypoid, partially circumferential, non-obstructing erythematous mass at the hepatic flexure (Figure 1). Immunohistochemical stains of the biopsies including CK7, P40, and KI-67 (50-60%) were found to be positive. The pathology of the hepatic flexure mass was consistent with squamous cell carcinoma. She successfully underwent surgical resection of the malignancy followed by chemotherapy treatment. Discussion: In conclusion, patients with colorectal SCC is extremely rare, but presents later in the disease process with a worse prognosis. Practicing clinicians should be aware of less common causes of colorectal malignancy as early identification with a diagnostic colonoscopy is essential. Due to the rarity of the case, extensive evaluation is needed to confirm the absence of primary disease anywhere else in the body.Figure 1.: Colonoscopy revealing a 5 cm polypoid mass at the hepatic flexure.