Adenosquamous Cell Carcinoma of the Rectum in a Girl: First Case Reported and Review of the Literature.

Adenosquamous carcinoma is a rare colorectal tumor with few cases described in the literature; no children have been reported. A 12-year-old-girl presented tenesmus, diarrhea, and iron deficiency anemia. Intestinal bowel disease was suspected, colonoscopy and biopsy were performed and the diagnosis was a squamous cell carcinoma. Chemoradiation therapy based on last colorectal cancer guidelines was started. Complete regression of the primary tumor was observed with lymph node progression. The pathology report of the lymphadenectomy revealed metastasis of adenosquamous carcinoma, although there was not any adenomatous component in the first biopsy. The patient presented progression with liver metastases, despite stable local disease due to response to first-line treatment of the squamous component.