Desmoid tumors. New aspects on diagnostic procedures, treatment and outcome

Abstract: Desmoid tumor (aggressive fibromatosis) is a rare, benign fibroblastic/myofibroblasticneoplasm that originates from musculoaponeurotic structures. It never metastasizes but locallygrows aggressively and infiltrates surrounding tissues. The treatment of choice has beensurgery. However, local recurrences are frequent. Other treatment modalities have been triedsuch as radiotherapy, chemotherapy, endocrine therapy, interferon, isolated limb perfusion(ILP) and non-steroid anti-inflammatory drugs (NSAIDs) with inconclusive results. Thenatural history of desmoid tumors is not well known, neither is the best treatment.The aims of this study were: 1. To investigate the outcome of desmoid tumors in patients withmore than 20 years´ follow-up. 2. To assess the clinical and radiological outcome in a seriesof patients with desmoid tumors left without treatment. 3. To evaluate factors that might be ofimportance for the development of recurrence in surgically treated patients as well as factorsthat might affect the course of the disease in patients with other or no treatment. 4. Tocompare the accuracy and potential pitfalls of fine needle aspiration (FNA) cytology and coreneedle biopsy in the preoperative diagnosis of desmoid tumors.30 consecutive patients (20 women) with desmoid tumors with more than 20 years´ follow-upwere reviewed. At follow-up, all patients except 1 were tumor-free in spite of the fact thatmany developed one or several local recurrencies. A retrospective review of 8 patients withdesmoid tumors followed without any treatment was undertaken. The patients were followedclinically as well as with imaging techniques (CT, MRI or sonography) with a mean followuptime of 4.4 years. 5/8 tumors decreased in size or disappeared. One tumor was stable and 2increased. 113 cases were analyzed with uni- and multivariate analysis for factors potentiallyinfluencing the risk for local recurrence. Primary treatment at tumor center, higher age of thepatient and tumor located in the abdominal wall were independent factors significantlyassociated with a lower recurrence rate. 69 patients with a definitive diagnosis of desmoidtumor with corresponding pre-operative FNA were retrieved. A correct pre-operativediagnosis was made in 50% of the cases. All patients but 4 had a benign FNA diagnosis. In 15cases where the FNA suggested desmoid tumor, the definitive diagnosis was other benignlesion in 13 cases and sarcoma in 2 cases. A correct diagnosis of desmoid tumor was made in24/26 cases with core needle biopsy and desmoid was the most likely diagnosis in 2 cases.Desmoid tumors are self-limiting to a much higher extent than previously known. Aggressivetreatment may be indicated only exceptionally. Treatment may cause more harm than benefit.A conservative attitude with long-term, repeated follow-up investigations may be advisable inmany cases. An accurate diagnosis, preferably using core needle biopsy, is essential.