CD34

Definition: CD34 is a monomeric cell surface sialomucin with a molecular mass of approximately 110 kD that is selectively expressed on human hematopoietic progenitor cells.

Function

At least three endothelial cell ligands can bind L-selectin:
 glycan-bearing cell adhesion molecule-1 (GlyCAM-1), a secreted proteoglycan found on HEVs of lymph node
 mucosal addressin cell adhesion molecule-1 (MadCAM-1), expressed on endothelial cells in gut-associated lymphoid tissues
 CD34, a proteoglycan on endothelial cells (and bone marrow cells).

The protein backbones of all these ligands are modified by specific carbohydrates, which are the molecules actually recognized by the selectins (SELs).

Expression in normal cells

 human hematopoietic progenitor cells
 endothelial cells
 adipocytes

Expression in tumors : CD34+ tumors

 lipomas
 solitary fibrous tumors
 dermatofibrosarcoma protuberans and giant cell fibroblastoma
 +/- acute leukemias
 nodular hairy dendritic hamartoma of the newborn
 smooth muscle hamartoma

Diagnostic use in IHC

 Differential diagnosis neurofibroma vs desmoplatic melanoma

• CD34 fingerprint appearance in NF (21457155)
• https://twitter.com/BenjaminAwood/status/817519970078715904

Open references

 https://www.archivesofpathology.org/doi/full/10.5858/arpa.2016-0598-RA

Paywall References

 CD61, CD31, and CD34 improve diagnostic accuracy in gastric antral vascular ectasia and portal hypertensive gastropathy: An immunohistochemical and digital morphometric study. Westerhoff M, Tretiakova M, Hovan L, Miller J, Noffsinger A, Hart J. Am J Surg Pathol. 2010 Apr;34(4):494-501. PMID: 20351488