alveolar soft part sarcoma

Introduction

unknown tissue of origin.

Epidemiology

• ~0.5% - 0.9% of soft tissue sarcomas in adults
• ~0.8% - 1.8% of soft tissue sarcomas in children
• most common between 15 and 35 years
• most commonly occurs in extremities especially deep soft tissues of thigh
• most common site in children is head & neck region especially orbit and tongue

Pathology

• poorly circumscribed
• necrosis and hemorrhage common
• early metastasis is characteristic
  • most common sites - lung, bone & brain
  • lymph node metastasis is uncommon

Microscopic pathology

• nests of large loosely arranged polygonal, uniform epitheliod cells surrounded by delicate connective tissue with endothelial lined vascular channels
• in some instances may grow as sheets of cells
• rhomboid or rod-shaped intracellular crystalline inclusions
• variable amounts of glycogen and diastase resistent granules
• infrequent mitoses
• vascular invasion almost invariable

Immunophenotype

desmin sometimes + s100, neuron specific enolase + in ~1/4 cases synaptophysin - chromogranin - neurofilament proteins - cytokeratin - EMA -

Genetics

• der(17)t(X;17)(p11;q25) fusion of TFE3 transcription factor gene (Xp11) with ASPL gene (ASPSCR1) at 17q25

Clinical manifestations

• slowly growing painless mass
• early metastasis is characteristic feature

More general terms

• soft tissue sarcoma (STS)

Patient information

alveolar soft part sarcoma patient information