Primary Mature Teratoma of the Rectum: A Case Report.

BACKGROUND Teratomas are embryonal neoplasms that contain tissues derived from 1 or more of the 3 germ layers. They commonly are found in the sacrococcygeal-gonadal location, sometimes in midline locations such as the mediastinum, retroperitoneum, and head and neck region. Primary rectal teratomas are extremely rare. Extragonadal teratomas can originate from pluripotent germ cells present in abnormal embryonic rests. CASE REPORT Here, we report a rare case of a primary mature, solid teratoma of the rectum. A 68-year-old woman presented with hematochezia and denied any history of abdominal pain or a change in bowel habits. Colonoscopy revealed a 4-cm pedunculated polyp in the rectum. No hair was present on its surface. The polyp was completely removed by polypectomy. Histologically, the tumor consisted of mature components from all 3 germ layers. Its surface was covered by squamous epithelium with hair follicles and sweat glands. Adipose tissue, blood vessels, bone, and glandular epithelium were present inside the mass. No evidence was found of immature elements or malignant features. CONCLUSIONS When polypoid lesions are found in the rectum, teratoma should be considered in the differential diagnosis. Histopathological confirmation is necessary to diagnose teratoma. Primary rectal teratomas should be distinguished from other neoplastic polyps as well as from local spread of teratomas arising in adjacent organs. These neoplasms are usually mature (benign) but may undergo malignant transformation. Therefore, complete resection is recommended to alleviate symptoms and avoid the risk of malignancy.