Progressive coarsening of appearance refers to the coarse and clumsy changes in the patient’s appearance due to skeletal lesions during the developmental process. It is one of the typical manifestations of mucopolysaccharide storage disease type I. It is a group of inherited disorders of mucopolysaccharide metabolism caused by lysosomal abnormalities. It is a group of inherited mucopolysaccharide metabolism disorders caused by lysosomal abnormalities, which is a congenital rheumatic disease caused by the accumulation of incompletely broken down glucosamine due to defective enzyme activity. The biochemical characteristics are defective acidic mucopolysaccharide catabolism resulting in excessive intracellular storage of mucopolysaccharides and excessive mucopolysaccharides in urine. So what is the differential diagnosis of gradual coarsening of appearance? The following is an introduction. The differential diagnosis of gradual coarse appearance is often distinguished from mucopolysaccharide storage disease type IV. The main manifestation of mucopolysaccharidosis type IV is usually detected at the age of 4 to 5 years due to difficulty in walking and the appearance of spinal deformity. The short stature is mainly due to a short spine and relatively long limbs that reach up to the knee when standing. Enlarged joints, especially at the wrists and knees, are spherical in shape. However, there is no joint ankylosis as in mucopolysaccharide storage disease type I and II. Knee inversion, flat feet, bending deformity of knee and hip joints on both sides, forming a semi-squatting posture. The wrist, hand, ankle and toe joints show hypermobility due to muscle ligament laxity. All of these external deformities have specific diagnostic significance. Intelligence is generally normal, and facial changes include a collapsed nasal bridge, widened distance between the eyes, and uneven teeth. Hepatosplenomegaly is rare. The age of onset of corneal clouding is later than that of mucopolysaccharide storage disease type I, and symptoms are usually apparent around the age of 10 years. Aortic valve insufficiency occurs mostly around the age of 10 years and its incidence increases with age. However, most patients die before the age of 20 years.