Hardness in the upper chest and lower throat may be caused by diseases such as chondritis, thyroglossal cysts, and sebaceous cysts. 1. Chondritis: Under the stimulation of inflammation, the rib cartilage will proliferate, which will lead to the expansion of the cartilage. This causes a localized bulge to harden. 2. thyroglossal cysts: these are caused by the remnant epithelium of the thyroglossal duct, which is incompletely degenerated by the embryonic thyroglossal duct, while the deeper tissues of the neck form the lumen, and a thyroglossal cyst is formed, which leads to hardness of the upper thorax and the lower part of the throat. 3. Sebaceous cyst: It is a cyst caused by the blockage of the skin follicles, the secretion cannot be discharged in time and stagnates in the follicles, which will appear to be hard to touch. If the symptoms of hardness in the upper chest and lower throat persist without relief, you need to seek medical treatment.