Four Cases of Dermatofibrosarcoma Protuberans With Clinical and Pathological Diagnosis Referred as Vascular Malformation Based on Imaging Diagnosis

Dermatofibrosarcoma protuberans (DFSP) is a rare, slow-growing, intermediate-grade malignancy of the subcutaneous tissue that is often misdiagnosed as a benign tumor. We report 4 cases referred to our clinic with magnetic resonance imaging-based diagnoses of “vascular malformations” but later confirmed as DFSP by pathology. All patients presented with soft or firm, well-defined masses showing high signal on fat-suppressed T2-weighted magnetic resonance imaging and contrast enhancement—findings typical of venous malformations. However, histological examination revealed storiform spindle cell proliferation and CD34 positivity. Myxoid changes and H3K27me3 positivity were observed in some cases. Differentiating DFSP from venous malformations on imaging alone is challenging due to overlapping signal characteristics. Homogeneous internal signals may help distinguish DFSP. In cases where treatment response is poor or clinical findings are atypical, early biopsy should be considered. Awareness of this diagnostic pitfall is essential to avoid delayed treatment.