Myositis ossificans

Case contributed by Dr Chris O'Donnell

Presentation

Painless enlarging lump in the anterior thigh. No history of recent trauma. Does play football.

Patient Data

Age: 17
Gender: Male
Ultrasound

Markedly echogenic mass with shadowing indicative of calcification in the quadriceps muscle.  No associated non-calcified mass.

MRI

Suggestion by another reporting radiologist to exclude "sarcoma"

Despite the dense calcification on US and x-ray, the mass is T2 hyperintense with minor susceptibility artefact on the gradient echo sequence. The mass also enhances peripherally and is centred on the central tendon of the rectus femoris.

X-ray

Subtle but well-circumscribed calcification in the anterior thigh at the site of the patient's palpable swelling.

Case Discussion

This is an important diagnosis to make radiologically so as to avoid biopsy. It actually looks more "sinister" on MRI than X-ray or US. Keys to the diagnosis are the circumscribed calcification on X-ray, location that is prone to trauma in the anterior thigh, and intimate relationship to the rectus femoris tendon.

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Case information

rID: 35714
Case created: 18th Apr 2015
Last edited: 21st Nov 2015
Inclusion in quiz mode: Included

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