Slide of the Week: CNS Mass

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.

CNS Mass


Click here to view whole slide image.


The most likely diagnosis is:

  1. Medulloblastoma
  2. Glioblastoma multiforme
  3. Metastasis from the colon
  4. 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?

  1. APC
  2. Wnt
  3. KITLG
  4. G6PD


Click here for the comparative pathology.

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.




Malignant tumors of the central nervous system associated with familial polyposis of the colon: report of two cases. Turcot J, Despres JP, St Pierre F.   Diseases of the colon and rectum.  1959 ; 2 : 465-468. PMID 13839882

Molecular Basis of Turcot’s Syndrome”   Hamilton et al, NEJM 332 839-847, 1995.

Digilio MC . Turcot syndrome. Atlas Genet Cytogenet Oncol Haematol.  August 2005 .

Evidence for a recessive inheritance of Turcot’s syndrome caused by compound heterozygous mutations within the PMS2 gene. De Rosa M, Fasano C, Panariello L, Scarano MI, Belli G, Iannelli A, Ciciliano F, Izzo P Oncogene. 2000 ; 19 (13) : 1719-1723. PMID 10763829

Hereditary nonpolyposis colorectal cancer and related conditions. Lucci-Cordisco E, Zito I, Gensini F, Genuardi M American journal of medical genetics. Part A. 2003 ; 122 (4) : 325-334. PMID 14518071

Development of a novel mouse glioma model using lentiviral vectors. Marumoto T, Tashiro A, Friedmann-Morvinski D, Scadeng M, Soda Y, Gage F, Verma I.  Nature Medicine 15, 110 – 116 (2008) Published online: 4 January 2009 | doi:10.1038/nm.1863




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