Can a Noncancerous Wound Be CD34 Negative?
Yes, noncancerous wounds are characteristically CD34 negative within the scar tissue itself, though CD34-positive cells actually increase in the surrounding pericicatricial tissue during healing. 1
CD34 Expression in Normal Wound Healing
In normal skin and wound healing, CD34 demonstrates a predictable pattern:
Normal dermis contains CD34-positive dendritic stromal cells distributed throughout, along with CD34 expression in endothelial cells, perifollicular cells, and eccrine glands 1
Mature scar tissue is completely devoid of CD34-positive stromal cells - the cicatricial tissue itself shows total absence of CD34 staining 1
Pericicatricial tissue (dermis adjacent to scars) shows significantly increased CD34-positive cells compared to normal skin (41.5 cells/mm² versus 24.5 cells/mm², p<0.001), suggesting these cells play a role in scar remodeling 1
Critical Diagnostic Pitfall
The augmented CD34 labeling around healing wounds and scars should not be misinterpreted as evidence of tumor persistence or recurrence, particularly when evaluating margins after excision of CD34-positive malignancies like dermatofibrosarcoma protuberans (DFSP) 1
This is especially important because:
- DFSP is typically CD34-positive in 92% of cases with diffuse staining 2
- CD34 immunohistochemistry may be used to aid margin assessment during DFSP excision 3, 2
- The physiologic increase in pericicatricial CD34-positive cells could be confused with residual tumor if this normal healing pattern is not recognized 1
CD34 in Other Benign Lesions
Some benign lesions can show variable CD34 expression:
- Cellular benign fibrous histiocytoma shows CD34 positivity in 6% of cases, though this should not deter from correct diagnosis based on morphologic features 4
- Benign breast lesions typically retain CD34 positivity in stromal myofibroblasts, unlike malignant tumors which lose CD34 expression 5
Clinical Application
When evaluating a wound or scar:
- Absence of CD34 in scar tissue is normal and expected 1
- Increased CD34 staining around the scar periphery is a physiologic healing response, not pathologic 1
- If concerned about tumor recurrence, correlate CD34 staining pattern with morphology - tumor cells show different architectural patterns than the dendritic stromal cells of normal healing 3, 2