[Back pain--when both patients and physicians are in deep waters]

Intraosseous pneumatocysts are rare and represent a benign condition. Such cysts can be an incidental finding described as a lytic process on plain X-rays. Computed tomography (CT) will confirm the diagnosis. Bone cysts filled with air are most frequently described in the iliac bone and in the sacrum, very rarely in the vertebrae or other bones.

This paper describes a patient that over a four to five-years period experienced relapses of rather strong lower back and hip pain of short duration during shallow water diving and ascent, and also during air travel.

Plain X-rays of the lower spine and left hip (prescribed because of an earlier hip trauma) demonstrated a lytic process in the left iliac bone. CT of the pelvis confirmed the diagnosis of an intraosseous pneumatocyst in the left iliac bone. A mini-invasive procedure with CT-guided puncture under local anaesthesia and destruction of the cyst relieved the patient's symptoms.

The physician should consider rear causes of lower back pain in otherwise healthy patients. As demonstrated here, the causal treatment can sometimes be quite simple.