S2972 Primary Squamous Cell Carcinoma of the Ileum - A Rare Entity

Abstract

Introduction: The small intestine is the most common site for metastatic spread in the gastrointestinal tract. Squamous cell carcinoma (SCC) from a wide variety of sites can metastasize to the small intestine. Primary SCC of the small intestine are rare. We present a rare case of primary SCC of the ileum. Case Description/Methods: A 70-year-old male presented with complaints of abdominal pain for 5 days. Physical exam revealed tenderness on palpation on the right lower quadrant. Labs significant for WBC count of 13k/ul and lactic acid of 10.9 mmol/l. CT Abdomen revealed small bowel obstruction and suspected perforated mass within the ileum. (figure A). Mesenteric lymphadenopathy concerning for metastasis. Laparoscopy revealed an ileal perforation with a matted mass of the distal small intestine which was resected and ileocolonic anastomosis was performed. Gross exam revealed a 6.8*4.7cm ill-defined mass, irregular in appearance with tan pink and nodular texture with areas of necrosis. The mass was submucosal in location, extending to the adjacent mesenteric soft tissue. Histology revealed an invasive poorly differentiated SCC with perforation and invasion of the mesenteric lympho-vascular spaces (figure B). Neoplastic cells were positive for p40(figure C), p63(figure D), ck5/6 and pancytokeratin while negative for ck7, ck20, cdx2, ttf1, synaptophysin, chromogranin, cd45 and S100. The patient had a prolonged postoperative course with multi organ failure, was made palliative on postoperative day 14 and he expired on the same day. Discussion: Several mechanisms have been proposed for primary SCC of the small bowel. Some of which include submucosal squamous epithelium undergoing malignant transformation, aberrant transformation of stem cells into squamous cells with subsequent malignant change. It is difficult to differentiate between primary versus metastatic squamous cell carcinoma of the small bowel. In our patient, imaging studies, immune-histochemical staining and histology results points towards a primary SCC of the ileum. We believe that our patient had primary SCC of the terminal ileum without underlying adenoma, inflammatory disease, or duplication. Optimal treatment and the prognosis are unknown because of the rarity of this condition. Surgery is the mainstay in the management of the disease. Due to the small number of cases available in the literature, the effects of chemotherapy and radiotherapy on the survival and recurrence are unknown.Figure 1.: A CT abdomen axial view showing irregular configuration of a loop of small bowel with adjacent air bubbles suspicious for a perforated mass located within the ileum. B Histology demonstrating tumor nests, composed of large cells with hyperchromatic, pleomorphic nuclei and eosinophilic cytoplasm infiltrating the muscularis propria. Neoplasm is diffusely positive for P40 (C) and p63 (D)-indicating squamous cells