Non‐polarizable collagen in dermatofibrosarcoma protuberans: a useful diagnostic aid

Abstract

The stroma in dermatofibrosarcoma protuberans (DFSP) stains with trichrome, but is not polarizable (birefringent, doubly refractile). The usefulness of polarizing neoplastic stroma as a diagnostic aid in distinguishing DFSP from dermatofibroma and fibromatosis was evaluated. Forty cases of dermatofibroma of all types, 12 cases of dermal fibromatosis, and 15 cases of DFSP were examined. None of DFSPs contained polarizable collagen, whereas 11 of the 12 (92%) fibromatoses and 35 of the 40 (88%) dermatofibromas did. Of the 5 dermatofibromas that did not polarize, all were composed primarily of round to polyhedral histiocytic cells, including foam cells, frequently surrounding small obliterated capillaries. Although not pathognomonic, the presence of nonpolarizable collagen appears to be an additional histological marker useful in differentiating DFSP from dermatofibroma and fibromatosis.

Utilization of polarized microscopy to differentiate deep penetrating nevus from equine type melanomas

“…Previous studies utilizing polarized microscopy reveal that mature type I collagen fibers are refractile, whereas the lack of refractile collagen in tumors such as dermatofibrosarcoma protuberans suggest that tumor stroma is often non‐refractile . Studies examining alopecia specimens have shown that polarized microscopy can be of value in the evaluation of scarring and non‐scarring alopecia .…”

CD44 and hyaluronate in the differential diagnosis of dermatofibroma and dermatofibrosarcoma protuberans

“…As the prognosis is different for each disease, making the histological distinction between DF and DFSP is a very important task for the dermatopathologist. Several histological properties and immunohistochemical markers including Factor XIIIa, human progenitor antigen (CD34) and the von Willebrand factor (VFW) have been proposed to distinguish DFSP from DF 1–17 …”