clear cell sarcoma of soft tissue

Digital cases

 Case 206 (HPC:206) : Clear cell sarcoma of soft parts
 Case 218 (HPC:218) : Clear cell sarcoma of soft parts

Definition: Clear cell sarcoma is now included under the uncertain differentiation heading (OMS, 2004) because, despite its clearly neuroectodermal nature.

Localization

 tendon and fascia
 bone
 digestive system (17000668)

Cytogenetics

 t(12;22)(q13;q12) causing a fusion of the EWSR1 and ATF1 genes

Molecular biology

 EWSR1/ATF1 fusion transcript by t(12;22)(q13;q12)
 EWSR1/CREB1 fusion transcript by a t(12;22) (17000668)

Expression profiling: 15150091

Differential diagnosis

 clear cell sarcomas

Cytogenetics in the differential diagnosis of clear cell sarcoma (melanoma of the soft parts) and primary cutaneous or metastatic melanoma

Clear cell sarcoma, in contrast to melanoma, has been found to contain a balanced t(12;22)(q13;q13) aberration in 50–75% of cases.

In diagnostically challenging cases, reverse transcriptase (RT)-PCR and FISH to detect this translocation represent valuable tools for the clinicopathological differentiation between these two entities, which may demonstrate significant overlap at the microscopic level, with an important impact on patient management and prognosis.

References

 Antonescu CR, Nafa K, Segal NH, Dal Cin P, Ladanyi M. EWS-CREB1: a recurrent variant fusion in clear cell sarcoma—association with gastrointestinal location and absence of melanocytic differentiation. Clin Cancer Res. 2006 Sep 15;12(18):5356-62. PMID: 17000668