The spine and long bones, especially the femur and tibia, preferably in a non-metaphyseal location, are the more common sites involved.
Small long bones of the feet follow in frequency.
Any other bone may be involved.
Clinical Symptoms and Signs
Local pain that may be of long duration is commoner in benign fibrous histiocytoma (BFH) than in its histologically similar counterpart, NOF.
Patients may be asymptomatic, the lesion being discovered incidentally.
Pathological fracture is exceptional.
Image Diagnosis
Radiographic Features
Radiographs show a medullar, central, or slightly eccentric well-defined radiolucent lesion.
Dense pseudoseptation may be seen.
Most lesions have sclerotic margins but a few of them may have irregular margins suggestive of aggressiveness.
CT Features
CT confirms absence of bone production, emphasizing the pseudoseptation and sclerotic margins.
MRI Features
MRI shows an isointense signal related to muscle on T1- and varying degrees of high signal intensity on T2-weighted images.
Bone scintigraphy may show moderately increased uptake.
Image Differential Diagnosis
Non-ossifying Fibroma
Their radiographic characteristics may be indistinguishable, but NOF has a clear preference for the metaphysis of long bones, especially the distal femur of younger patients than BFH.
Giant Cell Tumor of Bone
When in the end of a long bone, these two lesions may be indistinguishable by image methods, but GCT is more aggressive and can present earlier expansion to soft tissue; GCT also presents less or no sclerotic margins.
Chondromyxoid Fibroma
Can present very similar radiographic characteristics. By MRI, the chondroid component may be responsible for a high-intensity signal on T2.
Pathology
Gross Features
BFH cut surface shows a well-delimited medullar lesion.
The tumor tissue is firm, elastic, tan to whitish with yellowish areas.
Fractured lesions may show hemorrhagic or necrotic areas.
Histological Features
Histologically, BFH shows a mixture of spindle cells disposed in a predominant storiform fashion, a variable amount of osteoclast-type giant cells, foamy macrophages, hemosiderin, and chronic inflammatory infiltrate.
At higher power, the spindle cells’ nuclei are bland and with rare mitoses.
Multinucleated giant cells are scattered throughout the lesion.
Hemosiderin-laden cells are abundant in the stroma.
Collections of foamy histiocytes are also frequently seen.
Diffuse areas of mononuclear inflammatory infiltrate may also be present.
Pathology Differential Diagnosis
Non-ossifying Fibroma
Presents similar histologic findings as BFH, being distinguishable from it only on clinical grounds. NOF affects a younger population and is less bound to produce symptoms than BFH and is almost always located eccentrically or cortically in the metaphysis of a long bone.
Only gold members can continue reading. Log In or Register to continue
