Perinephritis

PERINEPHRITIS (perinephritis), inflammation of the kidney's own (fibrous) capsule, in contrast to paranephritis (see), which is inflammation of the perirenal adipose tissue. Perinephritis is encountered significantly less often than the latter, but is nonetheless of great practical interest, because it causes very distressing symptoms in patients and sometimes calls into question the continued existence of the kidney. Küster denied the possibility of independent inflammation of the kidney's own capsule without the simultaneous involvement of the perirenal adipose tissue in the process, which, in his opinion, plays the main role in perirenal inflammatory processes and is the site of their primary localization; the capsule itself, in his opinion, is affected only secondarily due to the direct spread of the process to it from the kidney or from the perirenal adipose tissue. Israel, Fedorov, and others assert that an independent lesion of the capsule itself can also occur, in proof of which cases of so-called perinephritis serosa, described by Coenen, Minkowski, and others, are cited. This process consists of inflammatory edema of the capsule itself, which, in Coenen's opinion, is a distinct anatomical formation possessing its own vascular and lymphatic network. With the further development of the process, a cyst filled with serous fluid forms in the capsule itself or between it and the kidney, against one of the walls of which the kidney is located (hydrocele renis, hydronephrosis perirenalis). The onset of the disease is acute, characterized by severe pain, and then by the formation of a tumor having the contours of the kidney. The process may undergo regression, yet giving periodic recurrences. The disease is rare. Its etiology lies in preceding kidney diseases (infarction, nephritis). Treatment is surgical: opening of the cyst, removal of its wall; in cases of deep changes in the kidney, nephrectomy is applied. Of significantly greater practical interest is chronic fibro-sclerotic perinephritis, which causes significant pathological-anatomical changes in the kidney's capsule, consisting of the development within it of productive chronic inflammation with fibro-sclerotic degeneration and the formation of dense, nucleus-poor connective tissue. The etiology of chronic perinephritis most often involves inflammatory processes of the kidney caused by pathogens of weak virulence (tuberculosis, infected nephrolithiasis). Rovsing believes that chronic perinephritis is caused by uric acid diathesis. Close in etiology to the fibro-sclerotic form is the fibro-lipomatous form of perinephritis, leading to the formation around the kidney of a large tumor consisting of adipose tissue. The process sometimes ends in so-called fatty replacement of the kidney. Both these forms of chronic perinephritis are relatively rarely encountered as an independent process, since the perirenal adipose tissue is almost always affected simultaneously. Clinical symptoms in the first form are characterized by significant, sometimes unbearable pain in the kidney region (perinephritis dolorosa); in the second form, by the appearance of a tumor that long retains the contours of the kidney, and the gradual fading of the function of the corresponding kidney. Treatment for secondary forms should be directed at the underlying kidney disease, of which chronic perinephritis is most often a late complication. In rare primary forms, decapsulation (see Kidney Decapsulation) and removal of the altered membranes are performed.