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

Renomedullary interstitial cell tumour
J.N. Eble
ICD-O code 8966/0
Renomedullary interstitial cell tumours
are common autopsy findings in adults
{2161,2163,2783}. They are present in
nearly 50% of men and women. About
half the patients who have one
renomedullary interstitial cell tumour
have more than one. They are asymptomatic
and while renomedullary interstitial
cells play a role in regulation of blood
pressure, renomedullary interstitial cell
tumours have no clear influence on blood
pressure.
Almost all renomedullary interstitial cell
tumours are 1-5 mm in diameter and
appear as white or pale grey nodules
within a renal medullary pyramid. Rarely,
they are larger {1604} and can form polypoid
masses protruding into the renal
pelvic cavity {896}.
Microscopically, renomedullary interstitial
cell tumours are seen to contain only
small amounts of collagen. The
renomedullary interstitial cells are small
stellate or polygonal cells in a background
of loose faintly basophilic stroma
reminiscent of renal medullary stroma. At
the periphery, renal medullary tubules
often are entrapped in the matrix.
Interlacing bundles of delicate fibers
usually are present. Some renomedullary
A
interstitial cell tumours contain deposits
of amyloid. In these, the delicacy of the
stroma is lost and irregular eosinophilic
deposits of amyloid are present within
the nodule.
Fig. 1.110 Renomedullary interstitial cell tumour
forms a white nodule in a medullary pyramid.
B
Fig. 1.111 Renomedullary interstitial cell tumour. A Well circumscribed tumour composed of spindle cells in
a basophilic matrix. B Note deposits of amyloid. C This example is sparsely cellular and composed of interlacing
bands of nondescript spindle cells.
C
74 Tumours of the kidney