Hard lumps on the tongue are mainly considered to be caused by pathological factors such as chronic papillitis of the tongue, vascular malformation of the tongue, tonsillitis of the tongue, ectopic thyroid gland and tongue cancer. 1. Chronic tongue papillitis: there are many papillary projections on the mucosa of the back of the tongue, including contour papillae, fungal papillae, filiform papillae, lobular papillae, etc. When these papillae become inflamed, they may become hard. When these papillae produce inflammation, protrusion and hyperplasia of tongue papillae can appear, which can be manifested as hard lumps on the tongue. 2. Tongue vascular malformation: there are abundant blood vessels in the tissue of tongue body, and there are many blood sinus curves in the endothelial cells inside, which cause tongue vascular malformation. If the blood in the sinus cavity coagulates and causes thrombus, the thrombus may calcify to form vein stones, which will be manifested as the symptom of hard lumps appearing on the tongue. 3. Tongue tonsillitis: there are a lot of lymphoid follicles protruding from the root of the tongue, separated by shallow grooves, and the whole lymphoid follicles are called tongue tonsils. When the inflammation of the mouth or throat involves the lingual tonsils, it can cause the proliferation of the lingual tonsils, resulting in the appearance of hard lumps on the tongue. 4. Ectopic thyroid: normal thyroid tissue should be located around the hyoid bone in the throat, but if there is developmental abnormality, thyroid tissue can appear at the back of the tongue root, which will be manifested as a hard lump with mauve color protruding on the tongue. 5. Tongue cancer: it is mainly categorized into infiltrative, ulcerative and exophytic types. It can be manifested as hard lumps on the tongue with unclear boundary, mostly accompanied by pain. Of course, the appearance of hard lumps on the tongue is not limited to the above reasons, so it is recommended to go to the hospital in time to find out the reasons for the appearance of hard lumps on the tongue, and then actively cooperate with the treatment, so as to avoid delaying the condition.