[Differences of the molecular phenotypes and the histogenesis between dermatofibroma and dermatofibrosarcoma...

To explore the histogenesis and differentiation of dermatofibroma (DF) and dermatofibrosarcoma protuberans (DFSP).

Clinical information and microscopic characteristics of 26 cases of DF and 26 cases of DFSP were investigated. The immunohistochemical study was performed on microarray sections by a panel of antibodies including Factor XIIIa, HLA-DR, CD34, CD14, S-100, MSA, and Ki67. Probe was labeled by in vitro transcription. The mRNA expression levels of TGF-beta and bFGF were investigated by in situ hybridization.

All cases showed positive for Factor XIIIa, HLA-DR and CD34 to different extent. The medians of positive rates in DF were Factor XIIIa 90%, HLA-DR 70%, and CD34 5%, and in DFSP were Factor XIIIa 10%, HLA-DR 5%, and CD34 80%. CD14 was positive in 3 cases of DF and 1 case of DFSP. S-100 was positive in 6 cases of DFSP and 2 cases of DF. MSA was positive in 5 cases of DFSP and 3 cases of DF. In all cases, positive rate of Ki67 was less than 5%. The mRNA expression levels of TGF-beta was elevated in DF in comparison with DFSP.

Both DF and DFSP can differentiate to dendritic cells (DC) in different degree. Considering the character of microscopic features and immunohistochemical phenotype, cells of DF are much similar to mature DC, while those of DFSP much similar to immature dermal reserve cell (DRC). The differences of cell differentiation between DF and DFSP result in different prognosis. DF is a benign tumor, while DFSP a low grade malignant tumor. The different expression of Factor XIIIa and CD34 may be helpful to differential diagnosis of DF and DFSP.