We report a patient with a novel adenomatous polyposis coli gene mutation leading to a severe phenotype including medulloblastoma, low-grade fibromyxoid sarcoma following cranial radiation, pilomatrixomas, colonic adenomas, and abdominal desmoid tumor following colectomy, all of which were successfully treated.
A 15-year-old girl with adenomatous polyposis coli gene (APC) mutation and brain tumor-polyposis syndrome developed an unusual succession of cervicocephalic tumors (medulloblastoma, meningeal low-grade myxoid tumor, and papillary thyroid carcinoma), at the age of 5, 9, and 15 years, respectively.
In patients with FAP and identifiable APC gene mutation, CNS tumors, especially medulloblastoma which developed in most cases during childhood, are more common in females with FAP and APC gene mutation in codons 686-1217.
APC is a critical component of the Wnt/Wingless signaling pathway, which is disrupted in sporadic cancers (e.g., colorectal adenomas, hepatocellular carcinomas, and medulloblastomas) by somatic mutations affecting multiple genes encoding alternative pathway components, including APC and CTNNB1 (encoding beta-catenin).
Medulloblastomas from children entered onto the International Society for Pediatric Oncology (SIOP)/United Kingdom Children's Cancer Study Group (UKCCSG) PNET3 trial (n = 109) were examined for beta-catenin immunoreactivity, and where tissue was available, evidence of CTNNB1 and APC mutations.
Germline mutations of APC in patients with Turcot syndrome (colon cancer and medulloblastoma), was well as somatic mutations of APC, beta-catenin, and Axin in sporadic medulloblastomas (MBs) have shown the importance of WNT signaling in the pathogenesis of MB.
A subset of cases is associated with colon cancer and APC germline mutations (Turcot syndrome), and APC and beta-catenin point mutations occur in up to 10% of sporadic cases, indicating the involvement of the Wnt pathway in the development of medulloblastoma.
The adenomatous polyposis coli (APC) gene, a member of the Wingless/Wnt signal transduction pathway, has been implicated in the development of medulloblastomas in Turcot's syndrome. beta-catenin also functions in this highly conserved signaling pathway and is instrumental in growth and development.
Although medulloblastoma is a component of Turcot syndrome with demonstrated APC mutations, APC gene deletions appear to be absent or very uncommon in patients with sporadic and NBCCS-associated medulloblastomas.