The main symptom of brownish-yellow disease arthritis is that the whole body skin, sclera and cornea pigmentation is brownish-yellow, the ear, nose and cartilage can become blue, the edge of the tympanic membrane is grayish-black, and the hearing is often reduced. Due to the lack of uronic acid oxidase, the intermediate metabolites of phenylalanine and tyrosine (uronic acid) cannot be further oxidized and decomposed, and accumulate in the body. This causes the skin, sclera and cartilage to become darker, while uronic acid causes hyperpigmentation of cartilage and other connective tissues, and degenerative arthritis of the spine and peripheral large joints. On the other hand, urinary black acid is excreted in urine, where it is alkalized and oxidized to make the urine darker, so it is also called black aciduria. This disease is a rare genetic disease and is rare. How to diagnose ear, nose and cartilage turning blue? After birth, patients with this disease have no symptoms other than placing urine oxidized to turn blackish brown to make diapers black. It is not until after 20 to 30 years of age due to excessive deposition of black uric acid that a series of symptoms are produced. The main symptoms of patients with this disease are brownish-yellow pigmentation of the skin, sclera and cornea all over the body, the ears, nose and cartilage may turn blue, the tympanic membrane is grayish-black at the edges, and hearing is often diminished. If uric acid is deposited on the aortic and mitral valves, the valves become stiff and murmurs appear. In men, the disease is often combined with black prostate stones. Bone and joint changes usually erode the spine first, followed by the knee, shoulder and hip. The incidence of spondylitis is 10% to 15%, more in men than in women. The patient complains of lumbar pain and examination of the lumbar plate, loss of pronation, mild hunchback deformity, and posture similar to that of ankylosing spondylitis. Progressive stiffness of the spine, degeneration of the intervertebral disc, narrowing, calcification, marginal bone formation, and involvement of the intervertebral ligaments, even eventually causing bony ankylosis. Degenerative changes in the joint tissues of the extremities due to pigmentation, loss of elasticity of articular cartilage, thickening of synovial fibrosis, subchondral bone erosion and cystic changes with bone denseness, sclerosis and formation of bone redundancy can lead to joint ankylosis. The synovial membrane of the joint shows villous hyperplasia and hyperpigmentation, and there is pigmented cartilage debris in the joint fluid. Since the peripheral arthropathy of this disease occurs later in browning disease and involves mostly large joints, and there is no difference in radiological signs from osteoarthritis, clinical attention should be paid to differentiate it from rheumatoid arthritis, ankylosing spondylitis and gout. In some patients with intervertebral disc cartilage calcification or heart valve calcification, they should also be differentiated from the corresponding diseases. A positive urinary black acid characterization supports the diagnosis of brownish yellow disease.