Fibromyxoma of the bone.

Fourteen patients with fibromyxoma of the bone, a rare but relatively overlooked entity, are described. This tumor is different from a chondromyxoid fibroma in age distribution, clinical behavior and histologic appearance. Fibromyxoma occurs frequently in later life (after 50 years of age). It is usually not clinically aggressive and lacks the lobular pattern, chondroid matrix and cell variety of chondromyxoid fibroma. Secondary aneurysmal bone cysts developed in three patients. It behooves the pathologist to screen patients with aneurysmal bone cysts for evidence of pre-existing fibromyxoma, especially if the patient is less than 40 years of age. Treatment consists of curettage with or without cryosurgical procedures. Marginal excision may be necessary for an occasional aggressive lesion.