Alveolar Soft Part Sarcoma

Arch Pathol Lab Med. 2015 Nov;139(11):1459-62. doi: 10.5858/arpa.2014-0385-RS.


Alveolar soft part sarcoma is a rare neoplasm usually arising in the soft tissues of the lower limbs in adults and in the head and neck region in children. It presents primarily as a slowly growing mass or as metastatic disease. It is characterized by a specific chromosomal alteration, der(17)t(X:17)(p11:q25), resulting in fusion of the transcription factor E3 (TFE3) with alveolar soft part sarcoma critical region 1 (ASPSCR1) at 17q25. This translocation is diagnostically useful because the tumor nuclei are positive for TFE3 by immunohistochemistry. Real-time polymerase chain reaction to detect the ASPSCR1-TFE3 fusion transcript on paraffin-embedded tissue blocks has been shown to be more sensitive and specific than detection of TFE3 by immunohistochemical stain. Cathepsin K is a relatively recent immunohistochemical stain that can aid in the diagnosis. The recent discovery of the role of the ASPSCR1-TFE3 fusion protein in the MET proto-oncogene signaling pathway promoting angiogenesis and cell proliferation offers a promising targeted molecular therapy.

Publication types

  • Review

MeSH terms

  • Adult
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / genetics*
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism
  • Child
  • Chromosomes, Human, Pair 17 / genetics
  • Chromosomes, Human, X / genetics
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Oncogene Proteins, Fusion / genetics*
  • Oncogene Proteins, Fusion / metabolism
  • Proto-Oncogene Mas
  • Sarcoma, Alveolar Soft Part / genetics*
  • Sarcoma, Alveolar Soft Part / metabolism
  • Sarcoma, Alveolar Soft Part / pathology
  • Translocation, Genetic


  • ASPSCR1 protein, human
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Intracellular Signaling Peptides and Proteins
  • MAS1 protein, human
  • Oncogene Proteins, Fusion
  • Proto-Oncogene Mas
  • TFE3 protein, human