Dermatofibrosarcoma protuberans mimicking hemorrhoids: a rare case report.

Introduction and importance: Dermatofibrosarcoma protuberans is a rare soft tissue sarcoma. Perianal involvement is exceptional and may mimic benign anorectal disease, leading to delayed diagnosis. Case presentation: A 28-year-old man presented with 6 months of anal pain, pruritus, and intermittent bleeding, initially treated as hemorrhoids. Surgical excision of presumed hemorrhoidal tissue revealed dermatofibrosarcoma protuberans with fibrosarcomatous transformation and focally involved margins. Molecular testing confirmed COL1A1-PDGFB fusion. Staging PET-CT showed localized disease without distant metastasis. After multidisciplinary discussion, the patient underwent radical re-excision, including part of the internal anal sphincter. No residual malignancy was identified, and final margins were clear. Follow-up clinical assessment and imaging showed no evidence of recurrence. Clinical discussion: Perianal dermatofibrosarcoma protuberans is rare and can resemble common anorectal conditions. Fibrosarcomatous transformation increases the risk of recurrence and requires complete excision with negative margins. Histopathology and molecular testing are essential for diagnosis. Long-term surveillance is required because recurrence may occur years after treatment. Conclusion: Persistent or atypical anorectal symptoms should prompt a biopsy. Complete excision with negative margins remains the key treatment principle.