Rationale: Desmoid-type fibromatosis (DTF) is a rare, histologically benign, soft tissue tumour. Although incapable of metastasizing, the clinical course is unpredictable and can be aggressive because of local invasive growth. Various treatments are available including; surgical resection, radiotherapy, hormonal therapy and chemotherapy. Nowadays there is a trend towards a more conservative strategy with a wait and see policy because of high recurrence rates after surgical resection. Health-related quality of life (HRQL) is a corner stone in treatment choice and can be used during the disease for monitoring the impact of the disease on physical, psychological and social level. Additionally, HRQL can be in important endpoint for future clinical trials. Today, no HRQL-tools are available which capture the needs of DTF patients. The hypothesis is that patients with DTF have issues on several HRQL domains including physical, social and emotional well-being. For this reason we developed a list of items based on previous research. This study aims to evaluate HRQL issues experienced by DTF patients. Purpose: Multi-centre, cross-sectional, observational study to measure HRQL of DTF patients and to evaluate the prevalence of the experienced problems.