1. Case presentation Patient, female, 33 years old. Married, with healthy childbearing. At birth, the patient had a developmental deformity of the right arm and both hands, with reduced activity function. The affected limb grew gradually with age. In the past 5 years, the right upper extremity grew rapidly, the right forearm and hand were huge, the finger bones were thick and long, curved and oddly shaped, the right upper extremity grew down to below the knee, and the right palm was huge more than the human head. No family history. On examination: the right upper limb was 81 cm long, significantly thicker below the shoulder and 29.2 cm thick wrist circumference. the right thumb was 13 cm long, 6.6 cm wide and 20 cm thick. the right index finger was 15.5 cm long, 10 cm wide and 30 cm thick. the combined right middle finger and ring finger were 16 cm long, 13.2 cm wide and 39 cm thick. the right palm was 21 cm long, 16 cm wide and 12.3 cm thick. The skin of the right upper limb had three indented bands. The left upper extremity was 67.2 cm long, with a wrist circumference of 19 cm. the left 3rd and 4th fingers were 15 cm long, 6 cm wide, and 20 cm thick. the left little finger was 11 cm long, 5.2 cm wide, and 15 cm thick. the right little finger and left 1st and 2nd fingers were basically normal in shape. Bilateral wrist joint movement was limited, and skin sensation was normal. Auxiliary examination: X-ray: chest X-ray: the texture of both lungs was slightly thickened. The right thorax was smaller than the left. The physiological curve of the thoracolumbar segment was slightly protruding on the right side. Plain radiographs of both upper limbs: (1) congenital developmental malformations: huge, thick and long right upper limbs, giant hands, and deformed hands. The right humeral head is deformed. Giant finger syndrome in both hands, more so in the right side. The distal phalanges of the 3rd and 4th fingers of both hands were fused, and the fingers were deformed together. The soft tissue of the right upper extremity is extra thick. Left hand deformation, soft tissue hypertrophy. (2) Degenerative osteoarthropathy of all joints of both upper extremities (except the left shoulder joint), unclear bone structure of the bones of both wrists, more so on the right side. Disturbed alignment of the bony ends of the right elbow joint. The right wrist joint is subluxed. (3) There is a coarse vascular shadow in the soft tissue of the right forearm. (Figure 1, Figure 2, Figure 3, Figure 4 (omitted)) Deep venography of the right upper limb: the venous network of the right hand is dilated, the deep veins of the forearm are slightly dilated, the deep veins of the upper arm are slightly poorly displayed, and the deep veins are still patent. Laboratory tests: routine blood, liver and kidney function, blood sedimentation, rheumatoid factor, blood flow coagulation time and DNA were normal. Ultrasound: intrahepatic calcification foci. Upper limb lymphography: lymphatic reflux obstruction in both upper limbs, especially in the right upper limb, which was considered to be due to congenital developmental abnormalities. The congenital megaloblastic limb syndrome is caused by the developmental malformation of bone and joint, which existed at birth. The deformities are mainly abnormalities of bone and joint development or segmentation, with the former forming hypoplasia, hypoplasia, dysplasia and overdevelopment of each bone; the latter forming redundant bone, joint deformity and missegmentation. In addition, abnormal development of muscles, tendons and ligaments can also cause congenital malformations of the bones and joints. Deformities can occur anywhere, alone or in combination with multiple anomalies. The bones and soft tissues of the giant limb are hypertrophic and vary in size, from small ones involving only one or one finger (toe) to large ones affecting one side of the limb. The growth rate is faster than that of the healthy side and increases with age. There can be several types: (1) segmental hypertrophy, giant limb involving all or part of a limb, with giant fingers (toes) most common. (2) Hemilateral hypertrophy, i.e., hypertrophy on one side of the body. (3) Crossed hypertrophy, hypertrophy of one side or part of the body, combined with hypertrophy of one or more segments on the opposite side. The soft tissues of the hypertrophic limbs appear edema-like, with rough skin and coarse, long hair. The tissue connecting the fingers may be soft tissue only, or partially bone connected. In congenital megaloblastic limb syndrome, the x-ray manifestations are mainly abnormal changes in bone size, morphology, number, position and soft tissue, while the bone structure is generally normal. The joints of hypertrophic limbs often develop osteoarthrosis earlier due to excessive weight bearing. x-ray examination is the main method to diagnose this disease and its results are the main basis for the diagnosis of this disease.