Background:
Dermatofibrosarcoma protuberans (DFSP) is a rare mesenchymal tumour that can involve dermis, fat, muscle and fascia. Tumours are slow growing, presenting as a painless, rubbery plaques. The majority occur on the trunk, limbs, and head and neck respectively. It is an intermediate-grade malignancy with a low likelihood of metastasis but high rate of local recurrence. Surgical options include wide local excision (WLE), and Mohs micrographic surgery (MMS).
Case:
A 69-year-old male presented with a right dorsal thumb mass overlying his first MCPJ. Ultrasound demonstrated increased vascularity. MRI demonstrated a solid enhancing mass. Biopsy confirmed DFSP. He underwent excision with 1cm margin over his right thumb and reconstructed using a pedicled reverse radial forearm flap. Histology demonstrated DFSP, no sarcomatous change, close but clear margins. At his three-months he had a mature flap, and functional thumb. Oncological surveillance was 6 monthly review.
Discussion:
Literature recommends MMS or WLE for DFSP with margins ranging from 1-5cm.
Given the lack of access to MMS publicly in Australia WLE is the standard of care. There is an argument to limit resection margins to 1cm as an alternative to 2-5cm in selected patients, anatomical locations, and low grade tumours. High grade features include fibrosarcomatous (FS) changes. FS changes mimic high-grade sarcomas, whereas DFSP without FS are generally locally aggressive with low-to-no metastatic potential. This report demonstrates an interesting and rare case of DFSP and thumb salvage surgery that weighs the balance between oncological control, preservation of healthy tissue and functional morbidity.