# Dermatofibrosarcoma Protuberans: A Rare Anatomical Location of Dermal Sarcoma

## TL;DR

A rare skin tumor called DFSP was diagnosed and treated through surgery and confirmed with genetic testing, highlighting the importance of accurate diagnosis and proper surgical margins.

## Contribution

This case report emphasizes the diagnostic challenges and treatment outcomes of DFSP in an unusual anatomical location.

## Key findings

- DFSP was confirmed using histopathology, immunohistochemistry, and FISH analysis for the COL1A1-PDGFB fusion gene.
- Adequate surgical excision with clear margins significantly reduces recurrence rates compared to narrow or positive margins.
- Structured follow-up is essential to minimize recurrence and improve patient outcomes.

## Abstract

Dermatofibrosarcoma protuberans (DFSP) is a rare, slow-growing cutaneous sarcoma that presents diagnostic and therapeutic challenges. This case report refers to a 47-year-old female patient who presented to the dermatologist with a stable, asymptomatic, firm lesion located on the proximal lower extremity. Local surgical excision was performed, and the specimen was sent for biopsy, where histopathological analysis, along with immunohistochemistry, confirmed the diagnosis of DFSP. Fluorescence in situ hybridization (FISH) analysis was also conducted, serving a supportive role in the detection of the tumor by confirming the presence of a COL1A1-PDGFB (collagen type I alpha 1 chain-platelet-derived growth factor beta) fusion gene, which is found in the majority of affected patients. As the initial excision left close margins, a second one was performed with subsequent skin grafting, and the final histopathology confirmed clear borders.

The following clinical case highlights the necessity of prompt diagnosis in skin lesions that often mimic benign conditions but are, in fact, locally aggressive. It further underscores the paramount importance of adequate surgical excision with histologically healthy margins, as recurrence rates differ significantly based on the surgical technique; more specifically, after wide local excision (WLE), the possibility of relapse falls to 4%-20%, compared to cases with narrow or positive margins, which are associated with even higher rates. This emphasizes the need to secure clear margins after the final excision, along with a structured follow-up to minimize recurrence and improve patient outcomes.