TRAP (Tartrate resistant acid phosphatase)

Author: Nat Pernick, M.D. (see Authors page)

Revised: 1 December 2015, last major update June 2005

Copyright: (c) 2003-2015,, Inc.

PubMed Search: TRAP[title]

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Cite this page: TRAP (Tartrate resistant acid phosphatase). website. Accessed January 18th, 2019.
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)
Microscopic (histologic) images

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Giant cell tumor of bone - mononuclear and giant cells are positive (fig 1D)

Giant cell tumor of tendon sheath - mononuclear and giant cells are positive (fig 2C)