Dermatofibrosarcoma protuberans in pediatric patients: A diagnostic and management challenge

COL1A1: collagen 1 a1 DF: dermatofibroma DFSP: dermatofibrosarcoma protuberans FISH: fluorescence in situ hybridization JXG: juvenile xanthogranuloma PDGFB: platelet-derived growth factor-b INTRODUCTION Spindle cell tumors occur in the pediatric population and can prove to be aggressive clinically, as in the case with dermatofibrosarcoma protuberans (DFSP). Soft tissue sarcomas represent less than 1% of malignant tumors overall, and the prevalence of DFSP before 20 years of age is 1.0 per million. This malignancy is characterized by invasive growth, low frequency of metastasis, and a tendency to relapse locally, making it a high-morbidity tumor. DFSP has an insidious onset with slow growth, requiring a high index of clinical suspicion and ultimately a biopsy for diagnosis. The heterogeneous presentation of the tumor often leads to a delay in diagnosis, partly because of a differential diagnosis that includes a number of benign entities such as scars, vascular malformations, dermal dendrocyte hamartoma (CD34 dermal fibroma), dermatofibroma, and others. Histologically, DFSP exhibits small, elongated cells arranged in a storiform pattern extending into the subcutaneous fat. The infiltrative pattern of DFSP aids in distinguishing it from benign entities, which can have similar elongated cells in a storiform pattern that lack infiltrative features, but this is often not sufficient for definitive diagnosis. When classification of a spindle cell tumor is not evident through routine histopathology alone, immunohistochemistry studies and fluorescence in situ hybridization (FISH) for the platelet-derived growth factor-b (PDGFB) rearrangement can be useful ancillary tests.