Benign fibrous histiocytoma of bone is a term that has been used for a type of bone lesion considered histologically identical to non-ossifying fibroma but was distinguished on the basis that it was described in the adult population 1,2. The lesion needs to be differentiated from cutaneous or deep benign fibrous histiocytoma occurring in the skin that is also known as dermatofibroma 3.
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Terminology
As of the WHO classification of soft tissue and bone tumors (5th edition) the term 'benign fibrous histiocytoma of bone' is no longer recommended similar to other synonymously used terms such as ‘fibrous cortical defect’, ‘metaphyseal fibrous defect’ and instead ‘non-ossifying fibroma (NOF)‘ is preferred 4.
Clinical presentation
Typically presents with pain, and most often in the third decade.
Pathology
Only a few case reports have been published but locations these have occurred include:
- ribs
- pelvis: including the sacrum and ilium
- tubular bones: epiphysis or diaphysis
- commonly seen around the knee
Radiographic features
Plain radiograph and CT
- lytic, loculated, with a prominent sclerotic border
- a narrow zone of transition
- no matrix mineralization
- cortical expansion and soft tissue invasion are rarely seen
MRI
-
T1
- central low signal intensity
- peripheral enhancement
-
T2
- heterogeneous high signal intensity
- low signal in surrounding sclerotic bone
Bone scan
- may be positive
Treatment and prognosis
Surgical resection. Local recurrence is ~15% (range 5-25%).
History and etymology
Benign fibrous histiocytoma was first described by David Carl Dahlin in 1978 as the atypical counterpart of malignant histiocytoma 1,6.