Hard lumps in the flesh below the knee may be caused by sebaceous cysts, synovitis of the knee joint and tibial chondroma. 1. Sebaceous cysts: the sebaceous gland ducts below the knee of the calf are blocked, so that the sebum gradually accumulates, forming retention cysts. When the cysts abnormally increase in size, press on the local nerve tissues or infections, the symptoms of pain when pressed may appear. 2. Knee synovitis: prolonged strenuous exercise or improper exercise posture, sprain or injury to the knee joint, causing local aseptic inflammation, resulting in local edema or bleeding phenomenon, stimulate the local soft tissues, there will be a calf knee below the meat of the hard lumps when pressed on the symptoms of pain. 3. Tibial chondrosarcoma: If the patient suffers from tibial chondrosarcoma, the tumor may proliferate and grow outwardly and protrude on the skin surface, which leads to the symptom of pain when pressed when there is a hard lump in the flesh below the knee of the calf. As there are many causes of pain when pressed, it may also be subcutaneous lipoma of the calf knee, it is recommended to go to the hospital for examination and diagnosis in a timely manner, and give targeted treatment after clarifying the cause.