Stains & CD markers
TRAP (Tartrate resistant acid phosphatase)

Topic Completed: 1 June 2005

Minor changes: 12 August 2021

Copyright: 2003-2022,, Inc.

PubMed Search: TRAP[title]

Nat Pernick, M.D.
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Cite this page: Pernick N. TRAP (Tartrate resistant acid phosphatase). website. Accessed January 19th, 2022.
Definition / general
  • One of seven isoenzymes with different tissue distribution
  • TRAP is found in hairy cell leukemia; other acid phosphatases are found in red blood cells, prostate, white blood cell lysosomes
  • Sensitive and relatively specific for hairy cell carcinoma when combined with DBA.44 positivity (Am J Surg Pathol 2005;29:474)
Positive staining - normal
  • B lymphocytes of marginal zone, osteoclasts
Positive staining - disease
  • Hairy cell leukemia, mantle cell lymphoma (57%), splenic marginal zone lymphoma (some), primary mediastinal B cell lymphoma (54%), CLL/SLL (41%), giant cells in giant cell tumor of bone and soft tissue (Hum Pathol 2005;36:945)
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