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

Ossifying renal tumour of infancy
C.E. Keen
Definition
Ossifying renal tumour of infancy (ORTI) is
an intracalyceal mass composed of
osteoid trabeculae, osteoblast-like cells
and a spindle cell component, arising from,
and attached to the medullary pyramid.
ICD-O code 8967/0
ORTI is extremely rare, only 12 cases
have been reported in the English literature
{414,1184,2462,2715}. Males predominate
(9/12). Age at presentation was
6 days to 17 months.
The exact nature of ORTI spindle cells is
still uncertain. No cases have been
reported in association with Wilms
tumour or with WT1/WT2 gene syndromes
on chromosome 11p.
All cases presented with gross haematuria
except one which manifested as a
palpable abdominal mass. Calcification
of the tumour frequently suggests renal
calculus.
ORTI is grossly well circumscribed and
measures 1-6 cm in diameter.
Microscopically, there is a characteristic
coarse trabecular osteoid meshwork
Fig. 1.91 Ossifying renal tumour of infancy. Osteoid meshwork interspersed with cuboidal cells.
with interspersed large cuboidal
osteoblast-like cells that express EMA as
well as vimentin, but not cytokeratin.
Sheets of uniform spindle cells with
ovoid nuclei may entrap renal tubules.
The outcome has been uniformly benign
and conservative surgical management
is recommended.
Haemangiopericytoma
A. Vieillefond
G. de Pinieux
ICD-O code 9150/1
Less than 30 primary renal haemangiopericytomas
are reported in the literature
`788,1715,1992}. Most of them arise
in the renal sinus and the perirenal tissue.
There are no specific radiological
features. Paraneoplastic syndromes, like
hypoglycemia or hypertension, may
occur. These tumours are large, firm and
histologically composed of a proliferation
of fusiform pericytes separated by
numerous capillaries presenting a
staghorn configuration.
Immunohistochemically, the tumour cells
are positive for CD34, negative for CD31,
actin and CD99. Behaviour of haemangiopericytoma
is difficult to predict. Late
recurrence or metastases can never be
excluded, especially when the tumour
size is over 5 centimeters and mitotic rate
over 4 per 10 HPF. Some haemangiopericytomas
of the literature could be reevaluated
as solitary fibrous tumours {1595}.
These two entities share almost the same
histological pattern and the same imprecise
potential of malignancy.
62 Tumours of the kidney