Osteochondroma - exostosis, enostosis and thrombosis

Case contributed by Tom Molyneux
Diagnosis almost certain

Presentation

Presented to her chiropractor with left knee discomfort and a sense that there is something in her muscle. No history of recent trauma to the knee.

Patient Data

Age: 25 years
Gender: Female

Recumbent knee images

x-ray

An elongated bony exostosis is present arising from the distal metaphyseal region of the left femur on its anteromedial surface. It is directed away from the knee joint with its base blending imperceptibly with the underlying normal bone. The proximal unattached end is rounded. Other than its base, the lesion is well corticated and appears to be benign. No evidence of calcification is seen in proximity to the lesion despite these lesions having a cartilaginous cap (from ectopic physeal cartilage).

There is no break in the cortex.

This lesion has the characteristic radiographic appearance of a pedunculated osteochondroma.

Two additional findings are noted.

There is a small radiopacity at the level of the lesion's base In the anteromedial subcutaneous fat. This may represent an isolated phlebolith.

There is a small bone island (enostosis) in the left lateral femoral condyle.

Case courtesy of Dr. Justin Youssef (chiropractor).

A - pedunculated osteochondroma
B - phlebolith (suspected)
C - bone island

Case Discussion

This is a classic presentation of a solitary osteochondroma, which is the most common benign bone tumor to affect humans. 85% of patients diagnosed with osteochondroma have a single lesion 2.

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