Dermatofibrosarcoma protuberans with fibrosarcomatous transformation of the abdominal wall: a case report and literature review

Abstract

Introduction and importance: Dermatofibrosarcoma protuberans (DFSP) is a rare, locally aggressive cutaneous sarcoma. Its fibrosarcomatous variant (FS-DFSP) is an uncommon, high-grade subtype associated with increased risks of recurrence and metastasis. Case presentation: A 43-year-old woman presented with a left iliac fossa skin mass evolving over 20 years, recently characterized by ulceration and bleeding. Computed tomography showed a well-defined anterior abdominal wall mass, initially mimicking a desmoid tumor. Biopsy suggested leiomyosarcoma or FS-DFSP; staging workup was negative. The patient underwent complete en bloc resection under general anesthesia. Histopathology confirmed fédération nationale des centres de lutte contre le cancer (FNCLCC) grade 2 FS-DFSP (70% FS component), staged pT2. The immunohistochemical study showed diffuse labeling of tumor cells across both components for CD34, with no staining for smooth muscle actin and caldesmon. Postoperative recovery was uneventful. Due to close margins (3 mm) near the iliac bone, adjuvant radiotherapy was administered (60 Gy, 2 Gy/day, 5 days per week). No recurrence occurred at the 2-year follow-up. Clinical discussion: FS-DFSP poses diagnostic challenges due to nonspecific clinical and radiological features, requiring histopathological and immunohistochemical confirmation. While complete surgical excision is the cornerstone of treatment, adjuvant radiotherapy helps reduce the risk of local recurrence in cases with close or positive margins. Conclusion: Managing FS-DFSP requires precise staging, clear margins, and a multidisciplinary consensus, including adjuvant radiotherapy when anatomical constraints limit surgical margins.