Definition
A nodule is a small, solid bump or mass that can be felt under the skin or seen on an X-ray. It's larger than a papule (small bump) but smaller than a tumor. Nodules can occur in various parts of the body, such as the thyroid, lungs, or skin. They can be benign (non-cancerous) or malignant (cancerous), so they often require medical evaluation. Think of it as a little knot or lump that doesn't belong there. It is usually localized to a specific area.