A 20 year old HIV positive male presents with headache, nausea and vomiting following a seizure. History is notable for three surgeries to remove colonic polyps. Subsequent MRI brain scan with contrast reveals a mass in the left frontal lobe which is removed. The following image is an H&E stained section of the mass.
The most likely diagnosis is:
- Glioblastoma multiforme
- Metastasis from the colon
- Primary lymphoma of brain
You are told after the surgery that the patient also carried a diagnosis of Turcot Syndrome. If this is true, in which gene would you expect to find a mutation in this patient?
Scroll below for answers.
Answer 1: 2, Glioblastoma multiforme.
Answer 2: a, APC.
Key clinical features of Turcot Syndrome (also called Mismatch Repair Cancer Syndrome) include both colonic polyps and CNS malignancies. Interestingly, patients with Turcot syndrome have a 92% higher incidence of medulloblastomas and gliomas than occur spontaneously. About 2-3 spontaneous cases of glioma occur per 100,000 people in both the European and North American populations. Turcot syndrome has been described as having either an autosomal recessive or dominant inheritance pattern. Either the APC gene or the mismatch repair genes (MLH1, MLH2, MLH6 or PMS2) have been implicated. These genes also are thought to underlie a disease similar to Turcot Syndrome called Syndrome of Hereditary Nonpolyposis Colorectal Cancer. Brain malignancies seen in these uncommon diseases with APC mutation are usually medulloblastomas, but if they have mutated mismatch repair genes they usually are glioblastomas.
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