Hard lumps in the middle of the two toes may be caused by tendon sheath cysts, corns and so on. 1. Tendon sheath cysts: tendon sheath cysts are chronic inflammatory changes caused by repeated wear and tear of the tendon sheaths of the toes, accompanied by fibrous tissue hyperplasia, the lumps are harder in texture, and some hard knots will appear at the toes. Tendon sheath cysts are relatively small and usually do not cause significant pain, but in the case of large tendon sheath cysts, recurrent frictional pain may occur. 2. Corns: Hard lumps in the middle of two toes, mainly due to squeezing when wearing shoes, resulting in some degree of keratinization of the toe area, thus forming corns. They are usually conical in shape and can be painful when walking. When the symptom of hard lumps in the middle of two toes occurs, it is recommended to go to the hospital as soon as possible and be treated under the guidance of the doctor.