Periosteal (Juxtacortical) Desmoid

Periosteal desmoid is a tumor-like fibrous proliferation of the periosteum at the musculotendinous attachment of the adductor magnus or the medial head of the gastrocnemius muscle on the posteromedial cortex of the distal femur. Because of its location, it also goes by the following names: distal metaphyseal femoral defect or medial supracondylar defect of the femur.

The etiology is thought to be related to repetitive trauma, similar to tug lesions elsewhere in the body. It is, therefore, also called an avulsive cortical irregularity.

The lesion tends to appear in children and young adults between the ages of 12 and 20 years, and usually resolves spontaneously soon thereafter. Patients are usually asymptomatic, but can present with pain.

Radiographic findings include a saucer-like cortical defect at the posteromedial cortex of the distal femur. The base is usually sclerotic, but may be poorly defined and irregular. Small bony spicules at the cortical surface may simulate an aggressive lesion.

Scintigraphy is usually normal, but focal increase in activity can occasionally be seen.

MRI reveals a T1-hypointense, T2-hyperintense lesion with a hypointense base at or near the attachment of the adductor magnus or medial head of the gastrocnemius muscles. Periosseous and marrow edema may also be seen.

Special thanks to Dr. Kavin Malhotra for the case and interesting discussion.

References

• Posch TJ, Puckett ML. Marrow MR signal abnormality associated with bilateral avulsive cortical irregularities in a gymnast. Skeletal Radiol. 1998 Sep;27(9):511-4.
• Resnick D, Greenway G. Distal femoral cortical defects, irregularities, and excavations. Radiology. 1982 May;143(2):345-54.