Desmoplastic Fibroma of the Bone. A Report of Two Patients, Review of the Literature, and Therapeutic Implications

Background: Desmoplastic fibroma (DF) is an extremely rare bone tumor. The recommendations for therapy are often based on limited personal experience, and the rate of local recurrence in the published cases is very high. Therefore, an analysis of treatment results of published cases was performed. Furthermore, DNA analysis of the tumors from two patients was also performed.

Methods: The clinical, radiologic, and histologic data of two patients with DF of the long bones are presented. DNA flow cytometry was performed on both DFs, three cases of abdominal fibromatosis, and three cases of extraabdominal fibromatosis. One hundred eighty-nine patients analyzed in the literature and our own 2 patients were evaluated with regard to epidemiologic, clinical, and histologic data, with particular emphasis on treatment results.

Results: DNA analysis of the locally infiltrating tumors revealed indices of proliferation between 21.5% and 24%, noticeably elevated values in comparison with extraosseous desmoid tumors (8.04%). Magnetic resonance imaging (MRI) was most valuable for imaging the intraosseous and extraosseous extent of DF. The evaluation of 191 patients (189 from the literature, 2 of the authors) showed the numbers of males and females to be equivalent, with a mean age of 23 years. DF has been reported in almost all bones, with a tendency to occur in the mandible and the long bones. Approximately 12% of patients presented with a pathologic fracture (20 of 161 patients). Infiltrative growth in the soft tissue was documented in 48% of patients. Three patients developed metastases after local recurrence. Analyzing the treatment results, the authors found a recurrence rate of 55-72% after nonresection procedures, and 17% after resection. No recurrences are reported after resection with wide surgical margins. The recurrence rate of tumors of the extremities was 55%, and 25% of these patients eventually required an amputation.

Conclusions: Considering the "semimalignant" character of this entity and the poor treatment results in patients with recurrent tumors, marginal or wide resection for primary treatment is recommended. The superior imaging quality of MRI greatly facilitates preoperative planning.