Desmoplastic fibroma of bone. A report of eight cases and review of the literature.

Desmoplastic fibroma of bone is a rare benign tumor consisting of thin, wavy fibroblasts set in an abundant matrix of collagen fibers. At times it is difficult to distinguish desmoplastic fibroma from other fibrous lesions, especially low-grade fibrosarcomas. Fewer than eight cases have been previously reported. We have reviewed the diagnostic and therapeutic findings of eighty additional cases. Six patients had the lesions located in an extremity and two had an axial lesion. The average age of the patients was twenty-five years (range, twelve to fifty-six years) and all of the patients had more than two years of follow-up (range, two to seventeen years). The radiographic findings in all but one patient were of a purely lytic, honeycombed lesion that often widened the bone, and was metaphyseal in long bones. The tumor replaced the medullary cavity with a grayish-white, rubbery to firm tissue that was often, but not always, contained by a rim of periosteal reactive bone. Histologically, the features were: (1) prominent loose bundles of fibrous tissue composed of slim, spindle-shaped fibroblasts with wavy, elongated nuclei; (2) variable amounts of bands of collagen fibers; and (3) absence of mitoses or atypical cells. Areas of metaplastic bone were found only around sites, of pathological fractures. The biology of desmoplastic fibroma is different from that of other benign fibrous lesions in that the lesion is very destructive locally and often recurs after incomplete excision. It is also distinguished from low-grade malignant lesions (for example, fibrosarcoma) in that metastases have never been reported. In our series an intralesional excision was initially performed in six of the eight patients and a marginal resection, in two. There were four recurrences, treated by a marginal resection in two patients and repeat curettage in one. The recurrence in the fourth patient required an amputation above the knee after two additional intralesional procedures had been unsuccessful. Wide or marginal resection appears to be the treatment of choice when the lesion is located in a site that can be resected without significant loss of function. In other areas, an attempt at curettage, instillation of phenol, and bone-grafting seems to be warranted, resorting to more radical procedures only if this fails to control local disease.