In order to induce heavy Pneumocystis pneumonia, rats were treated with dexame-, thasone twice a week for 14 weeks. Mature cysts, immature cysts and ruptured cysts were, identified on lung imprints. By phase-contrast microscopy mature cysts were spherical in, shape containing intracystic bodies both spherical and irregular, small to large trophozoites having polymorphic shapes, one nucleus and many vacuoles. Elcctro-microscopically, large amount of irregular trophozoites adhered to the surface of the type I alveolar epithelial cells in the alveolar cavity were observed. The above histological findings were typical features of Pneumocystis pneumonia (Figs. 1-8).

Objective: To explore the clinicopathological features and the renal biopsy process of a case of IgG4-related chronic interstitial nephritis with perirenal capsule involved and review associated literature to improve the clinician's understanding for this disease and to perform a better renal biopsy. Methods: The onset, diagnosis and treatment course of the disease were described and associated literature were reviewed to summary the clinicopathologic features and key points in renal biopsy. Results: The data of the patient showed that the urine specific gravity was 1.011, with urine protein ± and urine sugar 3+. The concentration of hemoglobin was 53 g/L, serum creatinine was 1665 μmol/L, and IgG4 was 9.39 g/L. Computed tomography showed that both kidneys enlarged slightly with decreased density and low density shadow around the kidneys. On contrast-enhanced scan, irregular low-density enhancement areas were found in both kidneys, and the edge of the boundary was not clear. For the first renal biopsy, no renal parenchyma was found except mainly hyaline collagen fibrils. At the second time, 3 pieces of tissues were obtained, which showed chronic interstitial glomerulonephritis. The IgG4 positive plasma cells were about 60/HPF and the IgG4⁺/IgG⁺cells ratio was more than 40%. The diagnosis of IgG4-related chronic interstitial glomerulonephritis was confirmed. After corticosteroid treatment, the serum creatinine decreased to 502 μmol/L after the patient got rid of dialysis. Conclusions There are various manifestations of renal damage caused by IgG4-related disease. It is necessary to pay attention to the involvement of the perirenal capsule, and to balance the risk of bleeding and poor sampling in renal biopsy.