Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

A
B
Fig. 1.85 Rhabdoid tumour of the kidney. A Note sheet-like diffuse growth of monomorphic tumour cells overrunning a native glomerulus. B Nuclei are angulated
with prominent nucleoli.
Fig. 1.86 Rhabdoid tumour of the kidney. Note characteristic
vesicular chromatin, prominent nucleolus
and hyalin intracytoplasmic inclusion.
A
Fig. 1.87 Rhabdoid tumour of the kidney. A Strong cytoplasmic vimentin immunoexpression. B Transmission
electron micrograph showing intracytoplasmic intermediate filiments.
B
Somatic genetics
Biallelic inactivation of the hSNF5/INI1
tumour suppressor gene, which resides
on the long arm of chromosome 22, is the
molecular hallmark of RTK {242,2729}.
Inactivation of this gene is also seen in
morphologically similar rhabdoid
tumours which occur in the soft tissue,
brain, and occasionally other visceral
sites. All of these tumours typically affect
young children, and are usually lethal.
The hSNF5/INI1 gene encodes a protein
involved in chromatin remodeling that is
thought to regulate the accessibility of
transcription factors to DNA, and its inactivation
is thought to promote neoplasia
by altering gene expression secondary
to its effect upon chromatin structure.
Inactivation occurs via mutation, deletion
or whole chromosome loss, accounting
for the frequent cytogenetic finding of
monosomy 22 in these neoplasms.
Children with concurrent RTK and PNETlike
tumours of the posterior fossa of the
CNS frequently harbour germline mutations
in the hSNF5/INI1 gene {241}.
Inactivation of the second allele has
been shown to occur by different mechanisms
in these patients’ two cancers,
confirming the clinicopathologic impression
that these are independent neoplasm
{790,2311}. A familial "rhabdoid
predisposition syndrome" encompassing
renal and extrarenal rhabdoid tumours
has been described in which affected
family members harbour constitutional
inactivation of hSNF5/INI1 {2368,2588}.
Prognosis and predictive factors
Outcome is typically dismal, as over 80%
of patients will die of tumour within 2
years of diagnosis. The rare patients who
present with tumour confined to the kidney
may have a slightly better prognosis.
Rhabdoid tumour
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