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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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Synovial sarcoma of the kidney<br />

J.Y. Ro<br />

K.R. Kim<br />

P. Argani<br />

M. Ladanyi<br />

Definition<br />

Synovial sarcoma (SS) of the kidney is a<br />

spindle cell neoplasm that infrequently<br />

displays epithelial differentiation and is<br />

characterized by a specific translocation,<br />

t(X;18)(p11.2;q11).<br />

ICD-O code 9040/3<br />

Synonyms and historical annotation<br />

A subset of previously described embryonal<br />

sarcoma of the kidney is now recognized<br />

to be primary renal SS {112}.<br />

Epidemiology<br />

Age and sex distribution<br />

Renal synovial sarcoma occurs in an age<br />

range 12-59 years, with a mean of 35 years<br />

and shows a slight male predilection (1.6:1).<br />

Localization<br />

Tumour equally involves either kidney,<br />

but no bilateral tumours were identified.<br />

Clinical features<br />

Symptoms and signs<br />

Flank or abdominal pain with or without<br />

abdominal distension is the presenting<br />

Fig. 1.119 Synovial sarcoma of the kidney.<br />

symptom in more than half of cases.<br />

Macroscopy<br />

Most of the tumours are solid, but multiple<br />

areas of haemorrhage, necrosis and<br />

cyst formation can be observed on gross<br />

examination.<br />

A<br />

Histopathology<br />

Tumours are typically mitotically active,<br />

with monomorphic plump spindle cells<br />

and indistinct cell borders growing in<br />

short, intersecting fascicles or in solid<br />

sheets. Cysts are lined by mitotically<br />

inactive polygonal eosinophilic cells with<br />

apically located nuclei ("hobnailed<br />

epithelium"), and appear to be<br />

entrapped native renal tubules, which<br />

may be extensively dilated. Areas of<br />

solid aggregation or fascicles of the<br />

tumour cells alternating with hypocellular<br />

myxoid tissues, together with areas displaying<br />

a prominent haemangiopericytoma-like<br />

pattern, may be found.<br />

Rhabdoid cells in the tumour have been<br />

recently described {1253}.<br />

B<br />

Fig. 1.120 Renal synovial sarcoma. A Note prominent cystic change. B The cysts are lined by hobnail epithelium<br />

with abundant eosinophilic cytoplasm representing entrapped dilated tubules. C Higher magnification<br />

shows monomorphic small spindle cells.<br />

C<br />

Immunoprofile<br />

The tumour cells are consistently<br />

immunoreactive with vimentin and BCL2,<br />

frequently reactive for CD99 but desmin<br />

and muscle specific actin are negative.<br />

The tumour cells are often negative or<br />

only focally positive for cytokeratins<br />

(AE1/AE3, or CAM 5.2) and epithelial<br />

membrane antigen, but the epithelial lin-<br />

Synovial sarcoma of the kidney<br />

79

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