Osteochondroma - distal femur

Case contributed by Dr Ammar Haouimi

Presentation

Palpable lump at the right distal thigh.

Patient Data

Age: 17 years
Gender: Male
X-ray

Right knee

There is a pedunculated bony mass arising from the medial aspect of the distal femoral metaphysis and projecting away from the epiphysis. It shows a lobulated margin with ring and arcs calcification. No pathological fracture is seen. A small adjacent fibrous cortical defect is noted.

MRI

Right knee

The MRI sequences demonstrate that the medullary cavity, as well as the cortex of the bony lesion, are in continuity with those of the parent bone with thinning of the cortex. No fracture or adjacent soft tissue mass or abnormal enhancement on postcontrast sequences. 

The cartilage cap is well-identified on T2WI/STIR sequences and measures less than 8 mm in thickness in this case. The distal component of the bony lesion protrudes into the adjacent vastus medialis muscle.

Note the adjacent fibrous cortical defect is also well visualized on the MRI sequences.

Case Discussion

Radiographic and MRI features are characteristic of an osteochondroma of the distal femur, which is considered as the commonest location (30%).

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Case information

rID: 74977
Published: 12th Mar 2020
Last edited: 2nd Feb 2021
Inclusion in quiz mode: Included
Institution: Aurès Medical Imaging Center - Batna Algeria