Intraosseous pneumatocyst

Case contributed by Dr Mohamed Ismail Saber Ismail


Incidental MRI finding of periarticular low signal abnormality on the medial aspect of the right sacroiliac joint.

Patient Data

Age: 75 years
Gender: Male

CT pelvis (bone window) revealed: The lesion of interest noted in MRI appears as well defined rounded gas-containing cystic structure inside the bone (right sacrum) in the peri-articular medial aspect of the right sacroiliac joint. It measures about 1 cm in maximum dimension. It is not communicating with the adjacent sacroiliac joint. The overall density is about -980 HU.

Case Discussion

Acquired benign intraosseous pneumatocysts are findings with an incidence of about 9% in adults. They are commonly seen in the vertebral bodies, iliac bones, and sacrum (like our case). They are almost always asymptomatic although some cases may be associated with pain. In CT, they appear as well-defined cystic lesion with very thin wall and very low density and usually around -1000 HU.

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Case information

rID: 74720
Published: 25th Mar 2020
Last edited: 25th Mar 2020
Tag: ct, sacrum
Inclusion in quiz mode: Included
Institution: Bedford Hospital NHS Trust

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