Paralabral cyst

What it means

A paralabral cyst is a fluid-filled sac that forms next to the labrum, the ring of tough cartilage that rims and deepens the socket of a ball-and-socket joint, most often the hip or shoulder. When the labrum tears, a one-way valve effect can let joint fluid seep out through the tear and pool just outside the joint capsule, gradually forming a cyst. In other words, the cyst itself is usually a byproduct of the tear rather than a separate condition.

Why it appears on a CT or MRI report

MRI is the best way to see both the cyst and the labral tear that usually caused it, and reports typically describe the cyst's size, location, and its relationship to a specific tear along the labrum. Because the cyst essentially points back to the tear, radiologists will usually describe the labrum itself in detail, noting where the tear is and how large it is. Occasionally the cyst is large enough to press on a nearby nerve, most classically the suprascapular nerve near the shoulder or a branch near the hip, and the report will flag this since it changes how urgently the finding needs attention.

What it usually means

Many paralabral cysts are found incidentally and cause no symptoms beyond whatever the underlying labral tear itself produces, such as joint pain, clicking, catching, or a feeling of instability during certain movements. Patients often worry the cyst itself is the main problem and ask whether it needs to be drained or removed, but in most cases it isn't dangerous and doesn't need direct treatment; addressing the labral tear that's feeding it is usually the more relevant question. The exception is when a cyst grows large enough to compress a nearby nerve, which can cause muscle weakness or wasting in the shoulder or, less commonly, the hip, and this scenario is taken more seriously.

When to follow up

Discuss the finding with an orthopedic or sports medicine specialist, particularly if you have joint pain, clicking, or a sense of instability, since treatment is generally guided by the labral tear rather than the cyst alone. Many labral tears and their associated cysts are managed with physical therapy first. Surgical repair of the labrum, sometimes with drainage of the cyst at the same time, is considered when symptoms persist despite conservative care, or promptly if there's evidence of nerve compression causing new weakness, since nerve symptoms are more time-sensitive.

A plain-language way to picture it

Think of the labrum as a rubber gasket sealing the rim of a joint, keeping the fluid inside the joint where it belongs. A tear in that gasket is like a small split that lets fluid seep out under pressure each time the joint moves, and over time that seepage collects into a small blister just outside the seal. Patching the gasket itself, the torn labrum, is what actually stops the leak; simply draining the blister without fixing the split usually lets it fill right back up.