Case Author(s): Charles Pringle, M.D./ Tom Miller, M.D. , 10/18/95 . Rating: #D2, #Q4

Diagnosis: Multiple hereditary exostoses

Brief history:

Increasing right leg pain.


Anterior and posterior whole body images (the gray scale on the posterior image was intentionally changed to accentuate the findings)

View main image(bs) in a separate image viewer

View second image(xr). Anterior view of the right knee

View third image(xr). Lateral view of the right knee

Full history/Diagnosis is available below

Diagnosis: Multiple hereditary exostoses

Full history:

16-year old female patient with history of multiple hereditary exostoses and multiple prior surgeries. Now, the patient has increasing right leg pain.


19.5 mCi Tc-99m MDP i.v.


A focus of increased activity in the medial right tibia corresponds to the symptomatic area. There is also mildly increased activity about both knees extending outside the normal boundaries of the bones. Additional foci in the distal right and proximal left tibio-fibular regions are also seen. Plain radiographs of the right knee show multiple exostoses with increase in size of the posterior tibial exostosis since a previous study.


Multiple hereditary exostoses is an autosomal dominant disorder. The lesions are usually multiple and often bilateral, with the most common sites being the knee, pelvis, rib, scapula and elbow. The lesions generally stop growing when the nearest epiphyseal center fuses. Malignant transformation to chondrosarcoma occurs in less than 5% of cases.


The symptomatic right tibial lesion was surgically removed with pathologic findings consistent with a benign osteochondroma. The other two lesions seen on bone scintigraphy are being followed clinically.

Major teaching point(s):

The increased activity in the tibial lesion indicates increased metabolic activity but is not specific for malignant degeneration.

ACR Codes and Keywords:

References and General Discussion of Bone Scintigraphy (Anatomic field:Skeletal System, Category:Normal, Technique, Congenital Anomaly)

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Case number: bs036

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