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

Rhabdoid tumour
P. Argani
Definition
Rhabdoid tumour of the kidney (RTK) is a
highly invasive and highly lethal neoplasm
of young children composed of
cells with vesicular chromatin, prominent
nucleoli, and hyaline intracytoplasmic
inclusions.
ICD-O code 8963/3
Epidemiology
Rhabdoid tumour comprises approximately
2% of all paediatric renal tumours.
The mean age at diagnosis is approximately
1 year, and approximately 80% of
patients are diagnosed in the first 2 years
of life. The diagnosis is highly suspect
over the age of 3, and virtually nonexistent
over the age of 5. Most previously
reported RTKs over the age of 5 have
subsequently proven to be renal
medullary carcinomas {2795}.
Clinical features
The most common presentation is that of
haematuria. A significant number of
patients present with disseminated disease.
Approximately 15% of patients will
develop a tumour of the posterior fossa
of the brain that resembles PNET morphologically.
Fig. 1.82 Rhabdoid tumour. CT showing large focally
cystic tumour (left).
Macroscopy
Tumours are typically large, haemorrhagic
and necrotic, with ill defined borders
that reflect its highly invasive nature.
Fig. 1.83 Rhabdoid tumour showing extensive
tumour necrosis and haemorrhage.
Histopathology
These tumours are unencapsulated, and
feature sheets of tumour cells that
aggressively overrun native nephrons.
Vascular invasion is usually extensive.
Tumour cells characteristically display
the cytologic triad of vesicular chromatin,
prominent cherry-red nucleoli, and hyaline
pink cytoplasmic inclusions. A subset
of tumours may be composed predominantly
of primitive undifferentiated
small round cells, but on closer inspection
small foci of cells with diagnostic
cytologic features can be identified.
Immunoprofile
Nonspecific trapping of antibodies by
the whorled cytoplasmic inclusions can
give a wide range of false positive
results. The most consistent and characteristic
finding is that of strong vimentin
labeling and focal but intense labeling for
EMA.
Ultrastructure
The cytoplasmic inclusions correspond
to whorls of intermediate filaments having
a diameter of 8 to 10 nm.
A
Fig. 1.84 A, B Rhabdoid tumour of the kidney. The nucleus is vesiculated. The cytoplasm contains eosinophilic inclusions.
B
58 Tumours of the kidney