[Primary Squamous Cell Carcinoma of the Small Intestine-A Case Report].

Primary squamous cell carcinoma of the small intestine is extremely rare, particularly in patients without adenocarcinoma components. Here, we report a case of a patient with primary small intestinal squamous cell carcinoma along with a brief literature review. The patient was a 70-year-old woman who was referred to our hospital after undergoing lower gastrointestinal endoscopy at another institution for abdominal pain and anemia, which revealed a suspected perforation of a sigmoid colon tumor. Computed tomography revealed a tumor that involved the sigmoid colon, small intestine, and left adnexa, as well as a para-aortic lymph node metastasis that infiltrated the left renal vein. A tumor marker analysis showed elevated SCC antigen levels, endoscopic examination revealed findings suggestive of infiltration from other organs into the sigmoid colon, and a biopsy confirmed squamous cell carcinoma. No findings suggestive of primary squamous cell carcinoma were identified during the systemic examination. Palliative exploratory laparotomy with tumor resection(partial small bowel, sigmoid colon, and left adnexal resection)was performed. The pathological diagnosis was consistent with primary small intestinal squamous cell carcinoma with no adenocarcinoma components detected. Chemotherapy was proposed to improve the patient's prognosis, but the patient opted for best supportive care and died of the primary cancer approximately 6 months after surgery.