Dermatofibrosarcoma protuberans: a tumour of nestin-positive cutaneous mesenchymal stem cells?

P>Background There is an increasing body of evidence suggesting that malignancies arise from mutated stem cells, which has led to the formulation of the cancer stem cell hypothesis. It has also been suggested that cutaneous malignancies originate from a mutated stem cell. To date, mesenchymal tumours of the skin have not been the focus of the cancer stem cell hypothesis. A population of mesenchymal stem cells has recently been identified in the dermal compartment of the skin. These proposed stem cells are positive for the neuroepithelial stem cell marker nestin. Objectives To describe the expression pattern of nestin, a neuroepithelial stem cell protein, in dermatofibrosarcoma protuberans (DFSP). Methods Immunohistochemical evaluation of DFSP with a monoclonal antibody against nestin was performed using standard techniques. For comparison we also analysed dermatofibromas (DF). In addition, we used antibodies against CD34 and Factor XIIIa; the proliferation marker Ki67 was also used. Results Strong immunoreactivity for nestin was found in DFSP whereas all DF cases were nestin-negative. Conclusions We propose that DFSP may represent a clonal expansion of a nestin-positive mesenchymal stem cell which would put this tumour in line with other neoplasms for which the cancer stem cell hypothesis was formulated. We suggest the use of nestin as an additional marker for DFSP, especially in cases of negative immunoreactivity for CD34. Nestin may also be employed for margin evaluation of DFSP in micrographic (Mohs) surgery.