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

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

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Multilocular cystic renal cell<br />

carcinoma<br />

J.N. <strong>Eble</strong><br />

Definition<br />

A tumour composed entirely of numerous<br />

cysts, the septa of which contain small<br />

groups of clear cells indistinguishable<br />

from grade Ι clear cell carcinoma.<br />

ICD-O code 8310/3<br />

Clinical features<br />

There is a male:female predominance of<br />

3:1. All have been adults (age range 20-<br />

76 years, mean = 51) {650}. No instance<br />

of progression of multilocular cystic renal<br />

cell carcinoma is known.<br />

Macroscopy<br />

While cysts are common in clear cell<br />

renal cell carcinomas, only rarely is the<br />

tumour entirely composed of cysts. In<br />

these tumours the number of carcinoma<br />

cells is small and diagnosis is challenging<br />

{1835}. In order to distinguish these<br />

tumours with excellent outcomes from<br />

other clear cell carcinomas, ones containing<br />

expansive nodules of carcinoma<br />

must be excluded and diagnosed simply<br />

as clear cell renal cell carcinoma {650}.<br />

Multilocular cystic renal cell carcinoma<br />

consists of a well-circumscribed mass of<br />

small and large cysts filled with serous or<br />

haemorrhagic fluid and separated from<br />

the kidney by a fibrous capsule.<br />

Diameters have ranged from 25 mm to<br />

130 mm. More than 20% have calcification<br />

in the septa and osseous metaplasia<br />

occasionally occurs.<br />

Tumour spread and staging<br />

No tumour with these features has ever<br />

recurred or metastasized.<br />

Histopathology<br />

The cysts are usually lined by a single<br />

layer of epithelial cells or lack an epithelial<br />

lining. The lining cells may be flat or<br />

plump and their cytoplasm ranges from<br />

clear to pale. Occasionally, the lining<br />

consists of several layers of cells or a few<br />

small papillae are present {2561}. The<br />

nuclei almost always are small, spherical,<br />

and have dense chromatin.<br />

The septa consist of fibrous tissue, often<br />

densely collagenous. Within some of the<br />

septa there is a population of epithelial<br />

cells with clear cytoplasm. The epithelial<br />

cells resemble those lining the cysts and<br />

almost always have small dark nuclei.<br />

The clear cells form small collections but<br />

Fig. 1.23 Multilocular cystic renal cell carcinoma.<br />

do not form expansile nodules. These<br />

epithelial cells often closely resemble<br />

histiocytes, or lymphocytes surrounded<br />

by retraction artefacts. Increased vascularity<br />

within the cell clusters is a clue to<br />

their nature.<br />

Immunoprofile<br />

The cells with clear cytoplasm in the<br />

septa frequently react strongly with antibodies<br />

to cytokeratins and epithelial<br />

membrane antigen and fail to react with<br />

antibodies to markers for histiocytes.<br />

A<br />

B<br />

Fig. 1.24 Multilocular cystic renal cell carcinoma. A The septa of multilocular cystic renal cell carcinoma contain eptihelial cells which can be mistaken for lymphocytes.<br />

B The epithelial cells in the septa of multilocular cystic renal cell carcinoma react with antibodies to epithelial markers. EMA expression.<br />

26 Tumours of the kidney

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