bubble_chart Overview

In 1942, Jaffe et al. considered it a tumor and separated it from the category of giant cell tumors. In 1945, Hatcher pointed out that nonossifying fibroma is essentially a tumor-like lesion, also known as metaphyseal fibrous cortical defect. However, it is now believed that this lesion is pathologically indistinguishable from fibrous histiocytoma. The lesion contains multinucleated giant cells and is more commonly found in the cortical region of the metaphysis of long tubular bones.

bubble_chart Pathological Changes

(1) Gross Appearance: The tumor appears brown or dark red, with a nodular cut surface. The fibrous cortical defect in the metaphysis is composed of tough fibrous connective tissue. The tumor is surrounded by a thin shell of sclerotic bone tissue.

(2) Microscopic Examination: A large number of fibroblasts can be seen arranged in a swirling pattern, with a small number of scattered giant cells and foam cells visible. Many cells contain hemosiderin granules, but regardless of the abundance of cells, there is generally no osteogenesis within the tumor cells, which is characteristic of this disease. Reactive hyperplasia may occur in the adjacent bone tissue.

bubble_chart Clinical Manifestations

The disease commonly occurs in children and adolescents, with no significant gender difference. The lesions are mostly found in the long tubular bones of the lower limbs, such as the tibia, femur, and fibula, and are rarely found in other locations. Occasionally, lesions may also be found in the ilium and sacroiliac joints, or in the ulna and humerus of the upper limbs. Generally, the lesions are located at the upper and lower ends of the bone shaft and exhibit expansive growth, with a distance of 2.5 to 5.0 cm from the epiphyseal cartilage.

There are no specific clinical symptoms that aid in the diagnosis of this disease. It is usually discovered through X-ray examination. The lesions develop slowly and latently, and it may take several years before local pain and swelling are felt, mainly in the ankle, knee, and wrist joints. These symptoms are often mistaken for minor trauma. Occasionally, the disease may be discovered due to a pathological fracture.

X-ray findings show that the lesions grow eccentrically with clear boundaries, initially not far from the epiphyseal plate, and move towards the bone shaft as the bone grows. The tumor commonly occurs in the upper end of the tibia and the lower end of the femur. The lesions appear as lobulated, loose shadows, oval in shape, with a diameter of 4 to 7 cm. The cortex at the lesion site may become very thin and exhibit expansive growth.

bubble_chart Treatment Measures

Generally, surgical debridement and bone grafting are performed. If necessary, such as in the case of a tumor in the fibula, segmental resection may be considered. After thorough debridement or resection, the recurrence rate is very low, and the prognosis is good.

bubble_chart Differentiation

1. Giant cell tumor of bone: The connective tissue cells are larger, the giant cells are also larger and more numerous, whereas non-ossifying fibroma shows antagonism. The characteristics of this disease include an age range generally between 8 to 20 years, with the primary locations being the metaphysis and diaphysis. It has the potential to self-heal and has a low recurrence rate.

Xanthogranuloma: Since the disease can absorb fat during the healing phase, becoming foam cells, some suspect it to be xanthogranuloma, hence it should be noted.