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

Papillary adenoma of the kidney
J.N. Eble
H. Moch
Definition
Papillary adenomas are tumours with papillary
or tubular architecture of low nuclear
grade and 5 mm in diameter or smaller.
ICD-O code 8260/0
Clinical features
Papillary adenomas are the most common
neoplasms of the epithelium of the
renal tubules. Autopsy studies have
found papillary adenomas increase in
frequency in adulthood from 10% of
patients younger than 40 years to 40% in
patients older than 70 years {653,2163,
2854}. Similar lesions frequently develop in
patients on long-term hemodialysis and
occur in 33% of patients with acquired renal
cystic disease {1143}.
Macroscopy
Papillary adenomas are well circumscribed,
yellow to greyish white nodules
as small as less than 1 mm in diameter in
the renal cortex. Most occur just below
the renal capsule. The smallest ones usually
are spherical, but larger ones sometimes
are roughly conical with a wedgeshaped
appearance in sections cut at
right angles to the cortical surface.
Usually, papillary adenomas are solitary,
but occasionally they are multiple and bilateral.
When they are very numerous, this
has been called "renal adenomatosis".
Histopathology
Papillary adenomas have tubular, papillary,
or tubulopapillary architectures corresponding
closely to types 1 and 2 papillary
renal cell carcinoma {585}. Some
have thin fibrous pseudocapsules. The
cells have round to oval nuclei with stippled
to clumped chromatin and inconspicuous
nucleoli; nuclear grooves may
be present. Mitotic figures usually are
absent. In most, the cytoplasm is scant
and pale, amphophilic to basophilic.
Less frequently, the cytoplasm is voluminous
and eosinophilic, resembling type 2
papillary renal cell carcinoma.
Psammoma bodies are common, as are
foamy macrophages {2161}.
Somatic genetics
Loss of the Y chromosome and a combined
trisomy of chromosome 7 and 17
are the first visible karyotype aberrations
in papillary renal tumours. This combination
of genetic alterations has been found
as the sole karyotype change in small
papillary renal tumours from 2 mm to 5
mm in diameter, all with nuclear grade 1
{1373}. Based on these findings, it has
been suggested that papillary adenomas
Fig. 1.53 Multiple renal papillary adenomas.
aquire additional genetic alterations during
growth, which change their biological
behaviour {1369}. One CGH analysis studied
6 papillary tumours less than 6 mm
in diameter and observed gain of chromosome
7 in 4 specimens {2107}. These
data suggest that initiating genetic events
for papillary renal adenomas include
gains of chromosome 7 and loss of a sex
chromosome. Small renal tumours demonstrate
similar, but less extensive genetic
alterations than their papillary renal
carcinoma counterparts. The clinically
indolent course of small papillary tumours
may, in part, be a result of the lower number
of genetic alterations per tumour.
However, it is not possible to distinguish
adenomas and carcinomas by genetic
changes, because many carcinomas
show only few genetic alterations.
A
B
Fig. 1.54 Papillary adenoma. A Two papillary adenomas in the renal cortex. These type 1 adenomas have complex papillae covered by a single layer of small epithelial
cells with inconspicuous cytoplasm. B Papillary adenoma composed of complex branching papillae on partially hyalinized stromal cores.
Mucinous tubular and spindle cell carcinoma / Papillary adenoma of the kidney
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