Hairy cell leukemia

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High power magnification of a bone marrow trephine showing infiltration by hairy cell leukaemia.

Indolent B-cell neoplasm, abbreviated HCL. Named for the appearances on peripheral blood smears. The vast majority (>95%) harbour the BRAF V600E mutation.[1] Mutations in other parts of the BRAF gene are described, but rare.[2]

In the bone marrow, they are associated with heavy reticulin fibrosis, commonly resulting in dry taps.[3]

Clinical:[4]

  • Pancytopenia. Monocytopenia common in earlier disease.
  • Splenic enlargement.
  • No lymphadenopathy.
  • Good prognosis (with treatment), though (likely) not curable.

Gross

Features:[5]

  • Huge beefy red spleen.
    • Red as white pulp obliterated.

Microscopic

Features:[6]

  • Small cells (10-20 micrometers) with "Fried egg"-like appearance:
    • Well-demarcated fuzzy cell borders,
    • Clear/whispy cytoplasm and,
    • Central round nucleus.
      • Peri-nuclear clearing ("water-clear rim"[7]) -- key feature.

DDx:

Images

www:

IHC

Features:[8]

  • CD20 +ve, CD11c+ve, CD25 +ve, CD103 +ve, CD123 +ve, cyclin D1 +ve, DBA44 +ve
  • Annexin A1 +ve (only useful in heavy bone marrow infiltration as it is also positive in T-cells and granulopoietic cells)
  • BRAF V600E mutation-specific antibody
  • CD5 -ve.

Flow cytometry:

  • CD19 +ve, CD11c +ve, FMC7 +ve.

See also

References

  1. Ahmadzadeh, A.; Shahrabi, S.; Jaseb, K.; Norozi, F.; Shahjahani, M.; Vosoughi, T.; Hajizamani, S.; Saki, N. (Sep 2014). "BRAF Mutation in Hairy Cell Leukemia.". Oncol Rev 8 (2): 253. doi:10.4081/oncol.2014.253. PMID 25992240.
  2. Tschernitz, S.; Flossbach, L.; Bonengel, M.; Roth, S.; Rosenwald, A.; Geissinger, E. (May 2014). "Alternative BRAF mutations in BRAF V600E-negative hairy cell leukaemias.". Br J Haematol 165 (4): 529-33. doi:10.1111/bjh.12735. PMID 24433452.
  3. Galani, KS.; Subramanian, PG.; Gadage, VS.; Rahman, K.; Ashok Kumar, MS.; Shinde, S.; Mahadik, S.; Ansari, R. et al. "Clinico-pathological profile of Hairy cell leukemia: critical insights gained at a tertiary care cancer hospital.". Indian J Pathol Microbiol 55 (1): 61-5. doi:10.4103/0377-4929.94858. PMID 22499303.
  4. URL: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cmed&part=A34022. Accessed on: 20 August 2010.
  5. Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 326. ISBN 978-1416054542.
  6. URL: http://emedicine.medscape.com/article/200580-diagnosis. Accessed on: 18 August 2010.
  7. URL: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cmed&part=A34022. Accessed on: 20 August 2010.
  8. URL: http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=cmed&part=A34022&rendertype=table&id=A34029. Accessed on: 20 August 2010.