DERMATOFIBROSARCOMA PROTUBERANS TREATED WITH MOHS SURGERY - A CASE WITH CD34 IMMUNOSTAINING VARIABILITY

BACKGROUND. Immunohistochemical stains for CD34 antigen can help in di fferentiating dermatofibrosarcoma protuberans (DFSP) from other fibroh istiocytic tumors and in demarcating its surgical margins during Mohs surgery. However, variable expression of CD34 antigen in nodular areas can sometimes result in negative staining of tissue sections creating diagnostic and therapeutic dilemmas. OBJECTIVE. To show the variable expression of CD34 antigen in a DFSP tumor. METHODS. Case presentation of DFSP with immunohistochemical staining using the ABC peroxidase ma cromolecular complex. RESULTS. Microscopic examination of paraffin-emb edded sections showed CD34-negative DFSP tumov cells with positive sta ining of endothelial cells. On frozen sections at the time of surgery the tumor cells stained strongly positive for CD34. CONCLUSION. This c ase demonstrates the variable expression of CD34 antigen by DFSP tumor s and emphasizes the need to interpret with caution the results of the se immunostains during Mohs surgery.