👉 Tubercles are tiny, round, and often brownish-black structures in the skin that can appear on various parts of the body. These structures can be found in many different places, including the lungs, heart, brain, and joints. They may also occur at specific sites such as the nose or mouth, but they typically disappear over time. Tubercles are not usually harmful to health and are often harmless, although some people may experience allergic reactions if they come into contact with them.