Intestinal obstruction caused by primary adenosquamous cell carcinoma of the small intestine: A case report and review of the literature

Primary adenosquamous cell carcinoma (ASCC) arising from the ileum is an exceptionally rare malignant neoplasm exhibiting mixed glandular and squamous differentiation. The clinicopathological characteristics of ASCC have not been clearly determined due to its rarity. We herein report a case of a 74-year-old man with a successfully treated ASCC of the ileum. The patient visited a medical clinic due to abdominal pain. Abdominal computed tomography imaging revealed an intestinal tumor in the ileum. Prior to undergoing capsule endoscopy, the patient complained of severe abdominal pain due to intestinal obstruction from the patency capsule and the tumor. Thus, the patient was referred to our hospital for emergency surgery. Upon relieving the obstruction by partial resection of the ileum, an impacted patency capsule with a tumor with ulceration was identified. On histological examination, the tumor consisted of malignant glandular and squamous cell elements. The postoperative course was uneventful, without complications. The patient subsequently received adjuvant chemotherapy with oxaliplatin and capecitabine for 6 months. The patient has no evidence of recurrence 20 months after surgery. To the best of our knowledge, only 8 cases of ASCC have been reported in the English literature to date. This case serves as an important reminder to consider small intestinal carcinoma, including ASCC, in the differential diagnosis of intestinal obstruction.