Purpose of the study: Extra-abdominal desmoids tumours are benign tumours generally managed by more or less wide surgical resection. This surgery can be mutilating and carries a risk of recurrence to the order of 50% according to several authors.

Material and methods: We followed a series of 26 patients from 1989 to 2009 with non-operated extra-abdominal desmoids tumours. Our objective was to study the clinical, radiographic and pathological course of these tumours and identify prognostic factors. For 11 patients, no medical or surgical treatment was delivered beyond the diagnostic biopsy; for 15, the tumour recurred after surgery and no other adjuvant treatment was given.

Results: Twenty-four tumours stabilised at 13.2 months on average for primary tumours and 20.9 for recurrent tumours. Thus en general, the tumour progression was less than 3 years. In all cases, once the tumour stopped progressing, it did not progress again. One primary tumour regressed spontaneously and one recurrence continued to progress at last follow-up of 23 months. Surgery was not required for any of the patients, excepting biopsy procedures to confirm diagnosis. MRI was the exploration of choice for follow-up.

Discussion: This series, which is the largest devoted to followed extra-abdominal desmoid fibromas, confirms recent data in the literature. A wait-and-see attitude should always be discussed with this type of tumour.