Acta Dermato-Venereologica 99-12CompleteContent | Page 24

1160 INVESTIGATIVE REPORT Dermatofibrosarcoma Protuberans Re-excision and Recurrence Rates in the Netherlands Between 1989 and 2016 Charlotte VAN LEE 1 , Wilner C. KAN 1 , Sonia GRAN 2 , Antien MOOYAART 3 , Marc MUREAU 4 , Hywel WILLIAMS 2 , Rubeta MATIN 5 , Renate VAN DEN BOS 1 and Loes HOLLESTEIN 1,6 1 Department of Dermatology, Erasmus MC Cancer Institute, 3 Department of Pathology, 4 Department of Plastic Surgery, Erasmus MC Cancer Institute, University Medical Centre, Rotterdam, The Netherlands, 2 Centre of Evidence Based Dermatology, University of Nottingham, Nottingham, 5 Department of Dermatology, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK, and 6 Department of Research, Netherlands Comprehensive Cancer Organization (IKNL), Utrecht, The Netherlands Dermatofibrosarcoma protuberans is a rare soft tissue tumour with a very low (< 0.5%) rate of metastasis. Rates of re-excision and recurrence were determined using data from the Netherlands Cancer Registry be­ tween 1989 and 2016. Of the 1,890 instances of der- matofibrosarcoma protuberans included, 87% were treated with excision, 4% with Mohs micrographic surgery, and 9% otherwise or unknown. Linked patho­ logy data were retrieved for 1,677 patients. Half of all excisions (847/1,644) were incomplete and 29% (192/622) of all re-excisions were incomplete. The cumulative incidence of a recurrence was 7% (95% confidence interval (CI) 6–8) during a median follow- up of 11 years (interquartile range (IQR) 6–17). After Mohs micrographic surgery (n  = 34), there were no re- currences during a median follow-up of 4 years (IQR 3–6). Due to the high rate of incomplete excisions and recurrences after excision, this study supports the Eu- ropean guideline, which recommends treating derma- tofibrosarcoma protuberans with Mohs micrographic surgery in order to decrease the rate of recurrence. Key words: dermatofibrosarcoma protuberans; recurrence; surgical excision; histological clearance; Mohs micrographic surgery. Accepted Aug 12, 2019; E-published Aug 13, 2019 Acta Derm Venereol 2019; 99: 1160–1165. Corr: Loes M. Hollestein, Department of Dermatology, Erasmus Medical Centre Cancer Institute, Box 2040, NL-3000 CA Rotterdam, The Nether- lands. E-mail: [email protected] D ermatofibrosarcoma protuberans (DFSP) is a rare soft tissue tumour that originates from a transloca- tion of chromosomes 17 and 22, resulting in tumour cell proliferation of fibrohistiocytic lineage (1). Unlike most skin cancers, DFSP is a non-UV-related skin cancer (1). The overall standardized incidence rate in the Nether- lands and the USA is 4 per 1,000,000 person-years (2–4). Men and women are equally affected, and the peak in- cidence age is between 20 and 50 years (5–7). Although DFSP occurs mostly in adult patients, it rarely occurs in children until 20 years old in the USA (1.0 per 1 million) (8). DFSP is commonly located on the trunk (50%), prox- imal extremities (20–30%) or head and neck (10–15%) (5–7). It presents as an asymptomatic, slowly growing, doi: 10.2340/00015555-3287 Acta Derm Venereol 2019; 99: 1160–1165 SIGNIFICANCE Dermatofibrosarcoma protuberans is a rare soft tissue tu- mour, for which the quality of care is poorly studied. Ra- tes of re-excision and recurrence were determined using data from the Netherlands Cancer Registry between 1989 and 2016. Of the 1,890 dermatofibrosarcoma protuberans included, 87% were treated with excision, 4% with Mohs micrographic surgery, and 9% otherwise or unknown. Half of all excisions (847/1,644) were incomplete and 29% (192/622) of all re-excisions were incomplete. Of the pa- tients who received surgery, 7% needed multiple surgeries. Due to the high rate of incomplete excisions and recurren- ces after excision, this study supports the European gui- deline, which recommends treating dermatofibrosarcoma protuberans with Mohs micrographic surgery in order to increase the quality of care. skin-coloured indurated plaque. Al­though DFSPs rarely metastasize, they grow in a locally invasive manner into subcutaneous fat, muscles and sometimes bone (5, 6, 9). Clinically, and with imaging tests (e.g. magnetic reso- nance imaging (MRI) or computed tomography (CT)), DFSP are difficult to delineate because the tentacle-like invasion into subcutaneous tissue is often greater than suspected. As a result, multiple surgical procedures may be required to ensure complete clearance of DFSP. Until 2015, DFSP guidelines were lacking and, in the Netherlands, the majority of DFSPs were treated with standard excision. The European consensus-based inter- disciplinary guideline, which has been available since 2015, recommends treating DFSPs with Mohs micro- graphic surgery (MMS) in order to reduce the assumed high recurrence rate after standard excision (10). To date, outcome data for management of DFSPs are based on small cohorts of patients, with limited informa- tion on those lost to follow-up (6, 11). Previous studies report a wide range of rates of re-excision (3–81%) and recurrence (0–46%) of DFSP (6, 7, 9, 12, 13). This na- tionwide cohort study of DFSP with long-term follow-up aims to determine the rate of re-excision and recurrence, which is needed to inform patients, clinicians, and health policymakers in planning optimal treatment strategies and surveillance schedules. This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.