HSS Ultrasound Case 66

Clinical History 14 year-old girl with history of hard palpable mass along the anterior thigh which was first noticed several months prior.

The patient vaguely remembers being hit there 2 years prior. The patient had radiographs taken 4 months ago which were not available at the time of the examination.

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Diagnosis Pedunculated osteochondroma of the distal femur.

Discussion Osteochondromas are benign cartilaginous tumors that manifest as bony excrescences with a cartilage cap, most commonly occurring around the knee.

Osteochondromas can grow until the patient reaches skeletal maturity; thus they are typically diagnosed in pediatric patients or adolescents.

Although radiographs suffice for diagnosis, MRI can identify soft tissue complications that can occur as osteochondromas grow. Alternatively, osteochondromas may first be detected on ultrasound as ultrasound is often the initial imaging modality for evaluating masses presenting in the pediatric population.

On ultrasound, a mineralized exophytic lesion contiguous with the host bone is very suggestive, although radiographs should probably be obtained to confirm the diagnosis.

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Discussion Treatment is usually conservative, although surgical resection may be considered in symptomatic patients, as in our patient.

Intraoperative radiographs show the osteochondroma in our patient before (a) and after (b) surgical excision.

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