Fact-sheet: Lipoma of bone


Updated on 09/30/2019 at 4:34 PM

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Definition

Rare benign primary bone tumor (0.3% of lipomas)

There are three types of lipoma of bone: intraosseous, cortical, and parosteal.

Location: solitary, predominantly in the lower limbs, metaphysis of long bones. Classic sites: proximal femur (subtrochanteric region), proximal tibial metaphysis, calcaneus, and fibula

Clinical features

Usually asymptomatic.

Rarely painful, with soft tissue swelling or fractures complicating the intraosseous lipoma.

Occurs at any age and equally in men and women.

Radiography

- Well-defined lucency, bordered by a thin complete or incomplete rim of osteosclerosis.

- Central calcification or ossification (>50% of cases)

- Occasionally, bony trabeculae giving the tumor a septated appearance

- In cases of calcaneal location, certain nearly pathognomonic semiologic features are sufficient to preclude further investigation: a large lucency ringed by a thin osteosclerotic rim (geode) with central calcification (85% of cases), always located beneath the trabecular pattern of the sustentaculum (usual radiolucent zone).

CT

- Intraosseous lucency with fatty content showing negative densities (between -40 and -100 HU), bordered by a thin rim of osteosclerosis.

- Calcifications or cystic areas with densities on the order of 0 to 20 HU.

- No contrast enhancement.

MRI

- T1 hyperintense, intermediate signal on T2, and hypointense on fat-suppressed sequences (STIR, T2 fatsat).

- The calcifications, bony trabeculae, and peripheral osteosclerotic rim appear hypointense on all sequences.

- No contrast enhancement.

Management

- If typical (radiographs and MRI), with no clinical symptoms or fracture risk = no biopsy or treatment.

- In cases of fracture risk: curettage followed by filling of the new cavity with cement or bone graft.

Differential diagnosis

Calcaneal cyst:

- Same location (beneath the calcaneal sulcus), with fluid content

- Probably shared pathogenesis between lipoma and calcaneal cyst.