Polycystic kidney disease – pathology and pictures
D. Dimitrakov, Il. Bivolarski, B. Anavi, J. Dimitrakov
Giant kidneys in autosomal dominant polycystic kidney disease
The mean volume of the kidney in autosomal dominant polycystic kidney disease patients with hypertension is reported to be about 650 ml in males and below 500 ml in females. However, kidneys weighting up to 7-8 kg and as large as 45/25/20 cm have also been reported. Since the rate of enlargement of the kidneys and the accompanying hypertension in autosomal dominant polycystic kidney disease patients are of crucial importance for the fatal outcome in autosomal dominant polycystic kidney disease, the above-mentioned figures have gained universal acceptance and have generally been perceived as the utmost limit of kidney size compatible with life.
We had the opportunity to follow a woman of short stature with autosomal dominant polycystic kidney disease, whose kidneys had enlarged to such an extent after ten years of haemodialysis that they had reached gigantic size beyond the one described as the upper limit compatible with life.
A 45-year-old female, weighing 79 kg and 156 cm in heght descended from a PKD-1 linked family with autosomal dominant polycystic kidney disease. There are 10 autosomal dominant polycystic kidney disease patients in four generations of her family. She had inherited the disease from her father and had transmitted it to one of her children. The disease had been diagnosed when she was 30. Five years later her renal function was still normal but she received symptomatic treatment for arterial hypertension and anaemia. During the next 10 years she had been on haemodialysis 3 times a week. Two years before her death progressive enlargement of both kidneys along with a sharp enlargement of the abdomen, dyspnea, low extremity edema and persistent therapeutically refractory hypotonia (blood pressure below 60 mm Hg) were observed. Nephrectomy was attempted but because of sudden collapse during the operation it was discontinued.
The hematologic and blood chemical values were as folows: Haemoglobin – 5,6 g/dl; Red blood cells count – 2,2×1012/l; Hematocrit – 0,20; White blood cells count – 6,5×109/l; Urea – 57.1 mmol/l (after haemodialysis – 28.1 mmol/l); Creatinine – 774 mmol/l (after haemodialysis – 460 mmol/l); Bilirubin – 19.0 mmol/l. The blood electrolytes were within normal limits. The EKG showed sinus tachycardia of 110 beats/min and diffuse repolarisation change consistent with ishemia.
On autopsy along with changes typical of chronic renal failure – cardiac enlargement, anaemia, nodular hyperplasia of the parathyroid glands and cerebral edema – change in the topography of the abdominal viscera due to the gigantic kidneys were observed. The kidneys occupied the larger part of the abdominal cavity. 3 litre of ascitic fluid and an umbilical hernia were present. The diaphragm was situated higher than usual and the thoracic volume was reduced in half. The lungs were deformed and pushed high above. The heart was in horizontal position and the large vessels partly folded. The ascending and descending colon were displaced laterally and overlaid the antero-lateral surface of the kidneys. In the central part of the liver (2150 gr) smooth-walled cysts, 1-3 cm in size, with clear fluid were observed. No vascular malformations were found in the brain.
The left kidney weighed 12.100 kg (48/28/23 cm) and the right kidney was 10.900 kg (50/26/20 cm). The configuration of the kidneys was preserved. A great number of cysts sticking together with a mean diameter of 0,5 to 6-7 cm on the surface as well as in the cortex and medulla on section plane were observed, projecting into the renal pelvis and deforming it. The walls of some of the cysts were semi-transparent but other were thickened and rigid even reach-jelly-like in others. Whitish remains from the renal parenchyma were observed between the cysts. No other pathologic changes in the urogenital system were observed.
On mikroscopic examination the remains of the parenchyma were found to be narrow, mainly fibrous streaks. The number of the glomeruli was reduced but most of them had a comparatively preserved glomerular strukture with slight deposits of hyalin along the mesangial axes and dilated Bowman spaces. A varying degree of sclerosis was observed in the rest of the glomeruli. Segmental hyperplasia (multilayered and with papiliform projections) of the epithelium varying from cuboidal to flat was observed in 13% of the section of the 176 cysts examined. Atrophic capillaries were found in the periphery of a great number of cysts. The basal membranes of the cysts were not thickened unlike those of the low-numbered atrophic tubules. Focal calcium and hemosiderin deposits and scanty lymphoid infiltrates were also found there. Advanced sclerotic changes were observed in the walls of the arterioles. The signs of chronic venous hyperemia were charasteristic of the remaining viscera. No exudative changes due to chronic renal failure were manifested.
The extreme cases of the therapeutic pathomorphosis are impressive with both the potential of the polycystic kidney disease and the unimaginably great compensatory capacities of the body and the possibility of sustaining life in borderline cases. In the case under discusion the weight of the kidney had increased nearly 100 time and accounted for 29% of the patient total weight while yheir length accounted for 1/3 of the patient height. We cannot say for sure what exactly initiated the enlargement of the kidneys during the last two years of the patient’s life but it is hardly determined by genetic factors, since none of the other patient in the family showed such a tendency. It deserves mention that the patient had two successful deliveries before the polycystic kidney disease was diagnosed. Although subsequent pregnancies are considered a rsk factor these deliveries did not initiate the kidney enlargement. The conventional therapy which the patient received during the last 10 years also cannot be assumed as related to the increase of the kidney size. It is beyond doubt, however, that by prolonging the life of the patient the medical treatment has significantly contributed to the maximum development of the cysts in number and in size. Undoubtedly, the lack of pyelonephritic changes and the relatively preserved glomeruli have both contributed to this. The segmental multilayered epithelium presumes hypersecretory origin of the cysts.
Our case is not contradictory to the concept that the size of the cysts and the development of hypertension are bad prognostic signs since death was observed in a relatively short period of time (2 years) after the initiation of the rapid kidney enlargement. Moreover, the gigantic size of the kidneys closely participates in the process of tanatogenesis by mechanically displacing the lung and folding the great vessel (the heart failure prevailed over the degree of renal inssufficiency). This case shows how important it is to choose the right time for the performance of binephrectomy and argues against the waste of time once it becomes evident that there is a tendency for rapid enlargement of the kindneys.