A polyposis genetic disorder with an onset in adolescence presenting with gastrointestinal multiple colorectal adenomas and primary central nervous system (CNS) tumors (eg, supratentorial glioblastoma and cerebellar medulloblastoma). Other clinical features include café-au-lait spots, cutaneous port-wine stain, and focal nodular hyperplasia.
Glioma Polyposis; Familial Polyposis Coli.
Described by Jacques Turcot (b. 1914), a Canadian physician, in 1959.
An autosomal recessive inheritance has been proposed for groups I and II (see Clinical Aspects below for a discussion of the groups). However, in group III, an autosomal dominant inheritance is strongly supported since this presentation is similar to the Familial Adenomatous Polyposis Syndrome. In addition, germ-like mutations in the mismatch repair gene hMLH1 or hPMS2 were found in some families. A mutation in the APC (adenomatous polyposis coli) gene between codons 697 and 1224 results in a 13-fold increased risk of developing medulloblastoma.
The relative risk of cerebellar medulloblastoma in patients with familial adenomatous polyposis is 92 times that of the general population. Glioblastoma multiforme is also considered a frequent tumor in association with this syndrome.
Based on clinical findings; in particular, the presence of multiple adenomatous gastrointestinal polyps is associated with neuroepithelial tumors of the CNS.
Turcot Syndrome has been divided into three groups based on the number and character of the colonic polyps.
Group I: Comprises patients who have 20 to 100 polyps that are larger than 3 cm in diameter. Malignant transformation usually occurs during the second and third decade of life and occurs in all affected individuals.
Group II: Comprises patients with small polyps numbering fewer than 10, whereas
Group III: Comprises patients with innumerable small polyps, usually more than 100. Gastrointestinal: usually colonic polyps that may be fewer in number, but larger than those found in other familial polyposis syndromes. The polyps are frequently associated with malignant transformation in the second or third decades. Tumors of the stomach, duodenum, and small intestine have also been described. CNS: neuroepithelial tumors—glioblastomas, medulloblastomas, and astrocytomas. Ophthalmic: congenital hypertrophy of the retinal pigment epithelium. Others: thyroid papillary carcinoma, “café-au-lait” spots.
Precautions before anesthesia
Careful neurologic history to exclude symptoms of CNS tumors. The presence of central nervous tumor necessitates an assessment of intracranial pressure (including fundoscopy), full blood count, and coagulation profile. Consider ABO cross-match for important invasive surgery. The radiological evaluation of all three groups is identical to that of patients with Familial Adenomatous Polyposis Syndrome.
Related to considerations for specific type and site of CNS tumor. The presence of ...