synovial sarcoma

Introduction

Mesenchymal neoplasm, unknown histogenesis does not derive from synovium or show any synovial differentiation.

Epidemiology

• 4th most common type of soft tissue sarcoma
• commonly metastasizes to lung & pleura.

Microscopic pathology

• biphasic pattern - with epithelial differentiation
• monophasic pattern - epithelial differentiation not apparent, mostly sheets of spindle cells
• poorly differentiated - oval to round cells, scant extracellular matrix, high mitotic activity

Immunophenotype

• biphasic: epithelial areas positive for:
  • K7, K8, K14, K18, K19 (extensive)
  • K17 (77%)
  • K13 (25%)
  • K16 (23%)
  • K6 (24%)
  • K20 (focal 27%)
  • EMA
  • calretinin (71% spindle or epithelial component)
  • HBME-1 (28/28 epithelial)
• monophasic: simple epithelial keratin positivity, usually focal
  • K7 (79%)
  • K19 (60%)
  • K8 (45%)
  • K18 (46%)
  • EMA (85%, patchy, clusters)
  • calretinin (52%)
  • HBME-1 (8/20 focal)

Genetics

• t(X;18) (p11;q11) chromosomal translocation.

More general terms

• soft tissue sarcoma (STS)

More specific terms

• synovial sarcoma/t[X;18][p11;q11]

Additional terms

• keratin

Patient information

synovial sarcoma patient information