What is a colloid cyst?

Thyroid?: Are you referring to a thyroid colloid cyst? If so, that would be a growth in the thyroid that could be benign but usually is evaluated with a thyroid biopsy if features are uncertain.

One type of nodule: Colloid is a yellow-brown liquid found in thyroids. Thyroid cells usually organize into hollow balls, or follicles, with colloid in their centers. Occasionally, cysts (large liquid-filled structures) can form in the thyroid. These often are filled with colloid, and may be called colloid cysts. Most cysts are not cancers, but 5% can have a cancer along an edge. A biopsy (fna) can determine this.