Unicameral bone cyst

Case contributed by Ammar Haouimi
Diagnosis probable


Painfull right arm following minor trauma a few days ago.

Patient Data

Age: 13 years
Gender: Male

A well-defined lobulated centrally located mid-diaphyseal lucent lesion of the left humerus measuring 40 x 20 x 18 mm with a homogeneous content, expanding the bone with thinning of the endosteum. A posterior periosteal reaction is noted with no evidence cortical breach is seen.


On MRI performed two weeks later, the diaphyseal lesion shows a homogeneous content of low signal on T1, high signal on T2 and STIR with a thin and regular peripheral enhancement. A periosteal reaction is noted, more obvious on MRI than CT with no evidence of a cortical breach or soft tissue component.

Case Discussion

CT and MRI features are suggestive of a unicameral bone cyst (UBC), also called simple bone cysts with posttraumatic periosteal reaction.

CT and MRI can be helpful in eliminating other entities that can potentially mimic a simple bone cyst (please refer to the article: unicameral bone cyst).


Additional contributor: Z.E Boudiaf, MD, CHU Constantine, Algeria

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