Xanthogranulomatous pyelonephritis

　　First, the etiology

　　1. The etiology of the disease is still unclear and may be related to the following factors:

　　(1) Bacterial infection leads to chronic inflammation, which causes continuous destruction of renal tissue, lipid release, and the formation of xanthogranuloma cells as the lipids are engulfed by tissue cells.

　　(2) Urinary tract obstruction combined with infection.

　　(3) Abnormal lipid metabolism.

　　(4) Immune dysfunction, especially the focal type of yellow granulomatous pyelonephritis is often due to low host immunity, so that mild inflammatory lesions in the renal parenchyma cannot heal spontaneously. Proteus and Escherichia coli are the most common pathogens. Staphylococcus aureus resistant to penicillin can also cause it.

　　Second, pathogenesis

　　Although it can be definitely confirmed that the disease is caused by bacterial infection and urinary tract obstruction can promote its occurrence, the pathogenesis is still unclear.

　　1. Pathological manifestations have two types:

　　(1) Focal type: less common, mainly manifested as yellow tumor-like masses within the kidney.

　　(2) Diffuse type: the affected kidney is significantly enlarged, most of which are pyonephrosis, with severe destruction of the renal parenchyma. Yellow tumor-like masses of varying sizes can be seen on the surface of the renal pelvis and calices or in the renal parenchyma. The lesions can extend to perirenal and extrarenal tissues, with extensive adhesion and fibrosis around the kidney, and involvement of surrounding adjacent tissues and organs.

　　2. Malek clinical staging:Ⅰst stage renal stage: the lesions are limited to the renal parenchyma, only invading 1 renal calyx or part of the renal parenchyma; Ⅱnd stage renal cycle: renal lesions are the same as in the Ⅰst stage, but have penetrated the renal parenchyma to invade the perirenal fat; Ⅲrd stage pararenal stage: the lesions are diffused in most or all of the kidney, and widely involve the perirenal tissues and retroperitoneum.

　　3. Under the microscope, the orange-yellow lesions are composed of inflammatory tissue: Its composition includes large foamy macrophages, small macrophages with granular cytoplasm, neutrophils, lymphocytes, plasma cells, and fibroblasts. A large number of neutrophils and necrotic tissue fragments can be seen around the renal pelvis mucosa. Foreign body giant cells can be occasionally seen. The cytoplasm of foamy macrophages, especially the cytoplasm of granular small macrophages, shows strong positive PAS staining.

　　1. In the absence of antihypertensive medication, systolic blood pressure ≥139mmHg and/or diastolic blood pressure ≥89mmHg, hypertension is classified into grades 1, 2, and 3 according to blood pressure levels. Systolic blood pressure ≥140mmHg and diastolic blood pressure

　　2. Obstructive nephropathy refers to the obstruction of urine flow in the urinary tract, which produces retrograde pressure and affects the normal physiological function of the renal parenchyma, leading to renal lesions. The degree of obstruction can be complete or partial; the scope can be bilateral or unilateral; the time can be acute and sudden or gradual; the location can be upper urinary tract or lower urinary tract; the upper urinary tract is above the junction of the ureter and bladder (ureter, renal pelvis, ureter-renal pelvis junction); the lower urinary tract is below the junction of the ureter and bladder (urethra, bladder neck, bladder-ureter junction). The influence on the kidney is related to the degree and duration of obstruction.

　　3. Ureteral calculi are not common in clinical practice, most of which come from the urinary system above the bladder, such as kidney stones, ureteral stones, or bladder stones. Stones may remain in the urethra or become impacted in the prostatic urethra, fossa navicularis, or urethral orifice when excreted. A few are secondary to urethral stricture, urethral atresia, foreign bodies, or urethral diverticula. Primary ureteral calculi are quite rare and are usually solitary stones. The stones complicated with infection are mostly composed of magnesium ammonium phosphate. Female urethral calculi mostly occur in the urethral diverticula.

　　This disease is clinically rare, often only one kidney is involved on one side, and bilateral lesions are rare; the vast majority of patients have renal area pain and recurrent urinary tract infections, fever (irregular fever), discomfort, fatigue, anorexia, weight loss, weight loss, and constipation. The time from the onset of clinical manifestations to diagnosis is generally 3 months to 9 years, 73% of patients have a history of stones, urinary tract obstruction, or diabetes, 38% have a history of urinary tract infection, 60% can palpate the lumbar mass, and 40% have hypertension.

　　The main preventive measures for this disease are as follows:

　　1. Adhere to drinking more water every day and urinating frequently to flush the bladder and urethra. Avoiding the reproduction of bacteria in the urinary tract is the simplest and most effective measure.

　　2. Pay attention to the cleanliness of the perineum to reduce the bacterial flora at the urethral orifice. If necessary, neomycin or furazolidone ointment can be applied to the mucosa around the urethral orifice or perineal skin to reduce ascending recurrent infection.

　　3. Try to avoid using urinary tract instruments, and strict aseptic operation should be carried out when necessary.

　　1. Urinary bacterial examination

　　Urine examination shows that more than 88% of patients have pyuria and proteinuria; the positive rate of urine culture is 74% to 86%, most of which are Escherichia coli and Proteus, occasionally Staphylococcus aureus resistant to penicillin can be seen. In the morning urine, centrifugation and smearing of the sediment can find foamy cells. If there are more than 5 foam cells on a single slice, the diagnosis of the disease can be made, and the positive rate reaches 82.6%.

　　2. Blood examination

　　Commonly, there is an increase in white blood cells and an acceleration of erythrocyte sedimentation rate; anemia is common, accounting for 65% to 78%.

　　Three, Imaging examination

　　1. X-ray examination:The radiographic changes of this disease are very inconsistent, and various focal or diffuse injuries can be seen, depending on the presence or absence of obstruction, stones, and other abnormalities. In 80% of patients, IVP can show non-opacification of the diseased kidney with stones, and变形 also occurs commonly, especially in patients with diffuse disease. Focal injuries are manifested as cystic or empty spaces within masses, with filling defects.

　　Renal angiography examination shows that the blood vessels in most yellow granulomatous renal lesions are reduced or absent, and small renal arteries without surrounding vascular branches can be seen. Pathological blood vessels are usually absent, and occasionally, some cases show an increase in blood vessels.

　　2. CT examination:Because renal angiography alone cannot accurately differentiate between XGPN, avascular solitary mass, or necrotic avascular adenocarcinoma, CT scan examination can clearly show multiple nodular or larger mass-like hypodense lesions within the kidney, and calcification foci in the renal pelvis or collecting system can be seen. In addition, localized XGPN may also have the following signs:

　　① One pole of the kidney is enlarged and deformed, with cystic density areas, CT values ranging from -15 to 30 Hu, which depend on the amount of fat, but do not present true fat density. After injection, there is obvious enhancement around the lesion, which is caused by the surrounding highly vascular granulation tissue. The yellow tumor lesions containing fat do not enhance.

　　② Localized renal masses, protruding beyond the renal outline, are isodense or slightly hyperdense, resembling renal cancer, but the enhancement is not obvious after enhancement. Due to the obvious enhancement of the surrounding renal parenchyma, the boundary of the lesion becomes very clear, and it appears as low density, which is different from renal cancer.

　　③ The morphological characteristics of localized lesions are mostly circular, reflecting the slow growth characteristics of the lesions.

　　④ It is easy to invade the perirenal space and psoas major muscle, and CT shows thickening of the renal fascia, and adhesion between the lesion and the psoas major muscle.

　　Four. Renal tissue pathological examination

　　1. Gross observation: The diseased kidney can be seen to be enlarged, with thickening and adhesion of the renal capsule and perirenal tissues. The lesions can present as a single tumor-like lesion localized in the first level of the kidney, or as a diffuse and multiple lesions. In the cross-sectional view, the renal pelvis and calyces are dilated, containing pus-like fluid and (or) calculi (often in the shape of a deer horn), and the renal parenchyma, especially the expanded perirenal tissues, are replaced by orange-yellow, soft inflammatory tissues. There are often multiple small abscesses surrounding it.

　　2. Under the microscope, renal tissue structure destruction can be seen, and the orange-yellow lesion tissue is composed of inflammatory large foam macrophages, small macrophages containing granular cytoplasm, neutrophils, lymphocytes, plasma cells, and fibroblasts, etc. A large number of neutrophils and necrotic debris can be seen around the renal pelvis mucosa. Occasionally, foreign giant cells and foamy cells can be seen, especially the cytoplasm of small granular monocytes, which show strong positivity in PAS staining.

　　Five. Magnetic resonance imaging (MRI) and ultrasound are also helpful in diagnosis.

　　1. Avoid spicy foods, seafood, irritants, beans, bean products, dried fruits, and other easily causing internal heat foods.

　　2. Avoid eating deer, cow, sheep, chicken, goose, dog, donkey meat, and their broths, bone soups, and other similar foods.

　　3. Patients with edema should consume a low-sodium diet; those without edema should not avoid salt; those with hematuria should drink more water.

　　4. Moderate exercise, persist in taking a walk every day. However, avoid intense activities and overexertion.

　　5. Prevent colds, avoid catching a cold; do not eat health care supplements and tonics to prevent internal heat and weight gain.

　　6. Be sure to build confidence, persist in treatment, adjust emotions, and maintain a peaceful and optimistic mindset.

　　7. Patients with renal failure and uremia should consume half a pound of milk, one egg, and one ounce of lean meat per day.

　　8. Keep the bowels smooth. It is advisable to defecate 2-3 times a day. If there is rhubarb (packaged separately) in the formula, the amount can be increased or decreased according to the defecation situation.

　　I. Treatment

　　Surgical treatment is an important method for this disease, and the prognosis after treatment is good. In the process of surgical treatment, it is necessary to recognize the difficulties and increased risks caused by the pathological changes formed by the spread of the lesion. Appropriate surgical plans should be formulated according to the clinical pathological stage to improve the safety and success rate of surgery.

　　1. Renal resection In most cases, the affected kidney is a diffuse type of lesion, with extensive destruction of renal tissue and loss of renal function. These patients usually undergo renal resection. It should be noted that in stage III patients due to widespread adhesions and fibrosis around the kidney, a nephrectomy should be performed through the abdomen to facilitate the separation of the affected kidney and the handling of the renal pedicle, otherwise, renal resection is extremely difficult and dangerous.

　　2. Nephron-sparing surgery This disease is a benign lesion. Some people propose that localized type I and II lesions be treated with local or partial nephrectomy to preserve the healthy renal tissue and achieve good clinical treatment effects. Literature reports that there have been 3 cases of nephron-sparing surgery, case 1 underwent local granuloma resection, and the postoperative recovery and follow-up were good; case 2 developed the disease due to ureteral calculus and infection, and after ureteral incision and stone removal, renal drainage, anti-infection treatment, the patient was cured and discharged, followed up for 3 years, the affected kidney had no recurrence, and the renal function was partially restored; case 3 was unable to be resected due to severe adhesions between the affected kidney and the descending colon and the posterior peritoneum, and only a biopsy was performed. The patient was treated with penicillin and streptomycin for anti-inflammatory treatment, and ultra-shortwave therapy was started from the 20th day after surgery, with a low dose, 20 minutes per time, once a day. After 5 treatments, the patient's back pain significantly decreased. After 10 treatments, the ultrasound examination found that the left kidney mass was significantly smaller than before. After 25 treatments, the ultrasound examination showed that the left kidney mass had disappeared. Subsequently, ultrasound examinations were performed multiple times, and no obvious masses were found. Anhalt also reported 1 case of left kidney lesion, which was cured after stone removal and drainage. In summary, for patients with mild renal destruction, surgical removal of urinary tract obstruction, enhanced anti-infection treatment, and reasonable physical therapy can achieve good therapeutic effects and relieve the patient of the pain of nephrectomy. Due to the difficulty in differential diagnosis between this disease and renal cell carcinoma, renal tuberculosis, it is easy to cause misdiagnosis before surgery, and the affected kidney is often resected. The application of nephron-sparing treatment methods is rare, so the correct preoperative diagnosis is extremely important for the selection of treatment methods for this disease. The treatment methods of nephron-sparing surgery are worthy of further research and application.

　　II. Prognosis

　　The prognosis of yellow granulomatous pyelonephritis is good. Osca reported 5 cases of focal resection of partial nephrectomy, with no local recurrence after 4 to 12 years of follow-up. In addition, there have been no reports of recurrence of the disease in the contralateral kidney after nephrectomy.