Tubular atrophic lesion, or focal segmental glomerulosclerosis (FSGS), is a common primary glomerular disease in children and adults with nephrotic syndrome (NS). It is characterized histopathologically by segmental glomerular scarring with or without intra-glomerular capillary foam cell formation and adhesions. Focal means that only part of the glomerulus is involved (50% of the glomerulus is involved); segmental means that part of the glomerular lobules are involved; and glomerulosclerosis means staged glassy changes or scarring of the entire glomerulus. Pathological features are mostly associated with tubular atrophy lesions and interstitial fibrosis. In typical FSGS with glomerular hypertrophy, the amount of urinary protein is low; cytogenic FSGS often has large amounts of proteinuria (>10g/d) and is prone to renal insufficiency. Blood creatinine >2 mg/dl has been reported in 60% of patients with cytotic FSGS, while only 10% of patients with typical FSGS have elevated blood creatinine. Collapsed FSGS also has more pronounced proteinuria, often >10g/d, and more severe renal insufficiency than other types, while hypertension is relatively rare. This type has a rapid onset and progresses rapidly, usually into end-stage renal failure (ESRF) 1 to 2 years after onset. The clinical presentation of pediatric patients is similar to that of adults, with a predominance of nephrotic syndrome and a lower incidence of hypertension and renal insufficiency than in adults. Most (40% to 60%) FSGS progresses chronically and eventually leads to renal failure, while a minority of patients (10% to 15%) progress more rapidly and develop renal failure earlier. A small number of patients have an upper respiratory tract infection or allergic reaction before the onset of the disease. The most common clinical first symptom is nephrotic syndrome. About 2/3 of patients have massive proteinuria and severe edema, and the amount of urine protein can be 1-30 g/d. About 50% of patients have hematuria, and microscopic hematuria is common, and occasionally carnal hematuria is seen. In adults, 30% to 50% of patients have mild persistent hypertension or chronic nephritis syndrome, patients with 24h urine protein <3.5g/d, edema is not obvious, often with hematuria, hypertension and renal insufficiency, while more than 50% can present the performance of renal syndrome, with obvious clinical manifestations of "three highs and one low". A small number of patients have no obvious symptoms, and proteinuria is occasionally found during routine urinalysis. Serum C3 concentration is normal and IgG level is decreased. The above symptoms may be aggravated by upper respiratory tract infection or allergy.