Intraosseous lipoma of the patella

Case contributed by Dr Bruno Di Muzio

Presentation

Left knee pain.

Patient Data

Age: 50-year-old
Gender: Female

Knee

Modality: X-ray

Narrowing of the medial joint compartment is noted. Irregularity of the superior pole of the patella is of uncertain significance. No further abnormality.

Knee

Modality: CT

No signs of fractures. Diffuse low attenuation of the bones. There is a well-defined fat attenuated lesion within the upper pole of the patella, showing sclerotic margins, no cortical breach and no periosteal reaction, consistent with a nonaggressive lesion - this may be an intraosseous lipoma, which can be painful.

Further characterisation with MRI may be considered.

Medial compartment joint space narrowing.There is a mild joint effusion.

Knee

Modality: MRI

In the patella, and there is a intraosseous lipoma.

There is a moderate joint effusion and chronic synovitis.

In the medial compartment of the knee, there is a chronic post root ligament tear of the meniscus associated with extrusion complicated by patchy grade 4 chondromalacia.

In addition, there is oedema in the medial femoral condyle and an ill-defined subcortical line in the weight-bearing portion consistent with an insufficiency fracture.

In the lateral compartment, there is a horizontal tear through the posterior horn of meniscus associated with a parameniscal cyst that measures 5 mm in size.

Cruciate and collateral ligaments are normal there is a small Baker's cyst. No popliteal fossa mass.

Case Discussion

The radiograph barely demonstrated the nonaggressive lesion within the patella. Further CT scan could not spot fractures, as clinical suspected, but confirmed the benign appearances of the patellar lesion. The MRI spotted that the symptoms are probably due to a subchondral insufficiency fracture of the medial femoral condyle, in the setting of chronic medial meniscal dysfunction. 

Intraosseous lipomas are rare benign lesions that account for less than 3% of all bone tumours

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Case Information

rID: 44075
Case created: 5th Apr 2016
Last edited: 9th Apr 2016
Tag: rmh
Inclusion in quiz mode: Included

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