Non-ossifying fibroma

Case contributed by Dr Jeremy Jones

Presentation

Tackled while playing football. Painful shin. Not weight-bearing.

Patient Data

Age: 14 years
Gender: Male
Modality: X-ray

Oblique fracture through a lytic bone lesion in the distal tibia. The lesion has a narrow zone of transition and the appearances of a benign bone lesion. It is eccentric and minimally expansile. 

3 months after presentation

Modality: X-ray

Healing of the fracture after 3 months.

Modality: CT

CT confirms the plain film findings: a lytic lesion with benign appearances and a possible cortical base. Differential includes non-ossifying fibroma.

Modality: MRI

The lesion is hyperintense on T2 with blooming artefact consistent with old haemorrhage. There is avid enhancement post-contrast.

MACROSCOPIC FINDINGS

Received fresh, five irregular pieces of brown and pale grey soft tissue admixed with some cancellous bone 37x32x15mm in aggregate.  One of the pale grey fragments shows an 8x5x3mm bright yellow area in the centre.  A portion sent for cytogenetic studies.  Representative sections after fixation.   A-rusty brown fragments.  B-fragments containing bright yellow area.  P2.

MICROSCOPIC FINDINGS

Much of the material consists of densely cellular tissue with streams and whorls of spindle shaped cells, often with a prominent storiform growth pattern. Scattered through this population are numerous multinucleate giant cells and some haemosiderin laden macrophages are present.  

There is no nuclear atypia. Occasional mitoses are present without atypical forms. In addition to this viable material, other fragments consist of necrotic debris surrounded by scar tissue with numerous haemosiderin laden macrophages and some spicules of degenerate bone. 

The histologic features need correlation with radiologic and clinical findings but are most in keeping with non-ossifying fibroma (metaphyseal fibrous defect). The areas of necrosis and haemosiderin deposition most likely relate to the recent pathological fracture.  Evidence of sarcoma is not seen. 

DIAGNOSIS

Histologic features most in keeping with non-ossifying fibroma (metaphyseal fibrous defect). 

Modality: X-ray

The lesion was packed and the post-operative appearances demonstrate increased attenuation in the lesion.

6 months post-packing

Modality: X-ray

6 months after packing had been performed, the bone is returning to normal with increased sclerosis at the site of packing.

3 years post-packing

Modality: X-ray

3 years after packing, there is subtle increased medullary sclerosis at the size of the previously packed lesion and the cortex appears normal.

Case Discussion

This cases demonstrates the longitudinal appearances of a pathological fracture in a benign bone lesion, that was histologically proven to be a non-ossifying fibroma.  Its subsequent treatment with bone packing and the subsequent radiographic features demonstrate near-normalisation of the bone packing.

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Case Information

rID: 23651
Case created: 30th Jun 2013
Last edited: 15th Oct 2015
Inclusion in quiz mode: Included

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