The diagnosis of DFSP-FS depends on finding a dermal tumor with characteristic areas consisting of spindle-shaped cells with atypical, vesicular nuclei aligned in smooth muscle-like bundled or herringbone patterns. The spindle-shaped cells are often rapidly growing as indicated by their relatively high mitotic index. These sites form from 5% to 100% of the tumor with any remaining sites consisting of DFSP lesions (i.e. bland, uniform, relatively slowly proliferating spindle-shaped tumor cells arranged in a characteristic cartwheel or whorled pattern). The diagnosis of DFSP-FS is strongly supported by finding that the tumors' cells express the COL1A1-PDGFB fusion gene; a finding that these tumor cells do not express or only weakly express CD34 protein strongly indicates that it is a DFSP-FS rather than a DFSP tumor. Individuals with DFSP-FS should have radiographic, CT scan, and/or magnetic resonance studies of the chest as well as ultrasound and/or CT scan studies of the abdomen and the lymph nodes which drain the tumor sites in order to determine if metastatic disease is present.
Dermatofibrosarcoma protuberans, fibrosarcomatous
Lymphoepithelioma-like carcinoma
Basal-like carcinoma
Mammary-type myofibroblastoma
Sclerosing epithelioid fibrosarcoma
Low-grade fibromyxoid sarcoma
Melanoma with features of a Spitz nevus
Neural fibrolipoma