Dermatofibrosarcoma protuberans: slowly gathering evidence for optimal treatment of a slow‐growing tumour
Authors: R.R. Bos
Journal: British Journal of Dermatology (2020)

Linked Article: Durack et al. Br J Dermatol 2021; 184:731–739. In this issue of the BJD, Durack et al.1 report on the surgical management of dermatofibrosarcoma protuberans (DFSP), a rare and slow-growing soft tissue tumour.1-3 They went to a great effort to review the charts of almost 500 cases of DFSP across the UK. DFSP rarely metastasizes but due to its tentacle-like invasion, lesions are larger than clinically suspected, leading to high recurrence rates after treatment. Standard care of DFSP has been surgical excision; however, current guidelines such as the European consensus-based interdisciplinary guideline recommend treating DFSPs with Mohs micrographic surgery (MMS) in order to reduce the probability of a recurrence. DFSP is rare and therefore randomized controlled trials are lacking. A Dutch cancer registry study on recurrence and re-excision rates of approximately 2000 cases of DFSP covering a period of almost 30 years showed that half of all standard excisions were incomplete, one-third of re-excisions were incomplete and the cumulative recurrence rate was 7% during a follow-up of 11 years.4 Comparable to the study of Durack et al.,1 no recurrences were observed after MMS, suggesting the advantage of MMS for DFSP. The majority of all patients in the study of Durack et al. were treated with wide local excision (WLE) and around 25% were treated with MMS.1 The authors found only six recurrences, all in the excision group and none in the patients treated with MMS. Almost 20% of standard excisions were incomplete at the first attempt. Recurrence rates in the current study were lower than previously reported (1.2% vs. 7%).1, 4 However, this is probably an underestimation as the median follow-up time of treated DFSPs in this study was very short (2.2 years). The Dutch study showed that half of all recurrences occurred after 2 years. Another reason for the difference in recurrence rates may be that the Dutch study included a nationwide linkage with the pathology database, meaning that if a patient was treated for a recurrence in another hospital, the recurrence was included in the analysis as well. In the study by Durack et al. the hospital charts were reviewed and treatment of a recurrence in another centre may have been missed.1 One of the advantages of a detailed chart review is that data on surgical margins were available for almost 80% of all patients with WLE, while these data are lacking in most studies. Generally, WLE is performed with a 2–4-cm margin, which is quite a large range. Durack et al. showed that in most cases the margins were sufficiently large, but due to the tentacle-like tissue invasion of DFSP, recurrences may have occurred.1 Too small margins may also lead to a recurrence. In two patients with a recurrence, the margins were small (1 cm); however, the anatomical location (i.e. head and neck) may have played a role in determining the surgical margin. In summary, this UK study adds knowledge on treatment results to the scant information we have on this rare tumour. Due to the short follow-up time, the recurrence rates after standard excision are probably underestimated. Evidence for the recommendation of MMS for treating DFSP of the European consensus-based interdisciplinary guideline is slowly being gathered. Despite the limitations, no recurrences were observed after MMS in both studies, suggesting that MMS is more effective for DFSP. I would like to thank Dr L.M. Hollestein for her suggestions on this commentary. Renate Ruth van den Bos: Conceptualization (equal); Writing-original draft (lead); Writing-review & editing (lead). The author declares no conflicts of interest.