From skin to pancreas: The unusual path of fibrosarcomatous dermatofibrosarcoma protuberans – A rare case report

Abstract

BACKGROUND: Dermatofibrosarcoma Protuberans (DFSP) is a rare, low-grade soft tissue sarcoma with a low risk of distant metastasis. The fibrosarcomatous variant (DFSP-FS) exhibits more aggressive behavior, an increased potential for metastasis to uncommon sites. CASE PRESENTATION: We present the case of a 43-year-old African male with a history of resected anterior abdominal wall DFSP-FS, who developed pancreatic metastases ten years postresection. The patient initially presented with a lung mass, which was confirmed as metastatic DFSP-FS after lobectomy. A subsequent cystic pancreatic lesion was incidentally detected during routine imaging. An endoscopic ultrasound-guided biopsy confirmed metastatic DFSP-FS. The patient underwent robotic-assisted distal pancreatectomy, achieving clear surgical margins, followed by adjuvant radiotherapy. Despite declining chemotherapy, he remains disease-free as of September 2024. DISCUSSION: DFSP is associated with a characteristic genetic alteration, the COL1A1-PDGFB fusion gene, driving tumor growth. While typical DFSP rarely metastasizes, DFSP-FS shows a higher incidence of distant spread, reported between 8 and 29 %. Pancreatic metastases are exceptionally rare, with fewer than five cases documented. Wide excision with negative margins remains the cornerstone of treatment, with Mohs micrographic surgery providing optimal local control. Advanced cases may benefit from imatinib, radiotherapy, or multidisciplinary surgical approaches, as demonstrated here. CONCLUSION: This case highlights the unpredictable metastatic behavior of DFSP-FS and display the importance of advanced diagnostic techniques, vigilant follow-up, and multidisciplinary management in achieving favorable outcomes in rare oncologic scenarios.