Fibromatoses of the oral and paraoral soft tissues and jaws. Review of the literature and report of 12 new cases.

The clinicopathologic features of 3 new cases and 28 cases obtained from the literature of fibromatosis of the oral and paraoral soft tissues and 9 new cases and 51 cases obtained from the literature of desmoplastic fibroma of the jaws are reported and reviewed. The results of the literature review show that all of the soft tissue lesions occurred before the age of 30 years (mean age, 8.3 +/- 7.0 years). There was a slight male predilection (male to female, 1.2:1). Most cases occurred in the paramandibular soft tissues and mandibular mucosa. Surface resorption of the underlying bone was a common feature. The recurrence rate was 22% and all of these were controlled with further therapy. The desmoplastic fibromas occurred in a slightly older age group (mean age, 14.7 +/- 12.1 years) although 88% of the patients were still younger than 30 years. There was no sex predilection. The vast majority occurred in the area of the mandibular body-angle-ramus. Radiographically, half were unilocular and half were multilocular. Some had poorly defined radiographic margins. The recurrence rate was 25%. The treatment of choice is surgical resection with wide margins, especially for cellular lesions and for those that erode bone with invasion of adjacent soft tissues. Microscopically, both peripheral and central lesions consist of variable proportions of collagen and fibroblasts with a uniform histologic appearance. Hyalinization of collagen is variable but is more frequent in the intraosseous lesions. The cells show no features of anaplasia, and although occasional mitoses may be found, they are always normal in appearance.