A case report of ascending colon adenosquamous carcinoma with BRAF V600E mutation.

A 78-year-old Japanese male was referred to our hospital with a 3-month history of anorexia and right abdominal pain. A colonoscopy showed circumferential narrowing of the ascending colon with deep ulceration. Biopsy was performed, and examination of the specimen demonstrated squamous cell carcinoma. Abdominal computed tomography demonstrated thickening of the wall of the ascending colon, multiple lymph node metastases, multiple liver metastases, and peritoneal dissemination. After right hemicolectomy, histological examination demonstrated adenosquamous carcinoma. Biomarker analysis showed a microsatellite stable, wild-type KRAS gene in exon 2 and BRAF V600E mutation. Despite undergoing intensive chemotherapy, the patient died 5 months postoperatively.