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Studies performed at large metropolitan medical centers have reported an increasing incidence of idiopathic focal segmental glomerulosclerosis (FSGS) in adults. To determine whether a similar trend occurs in small urban and rural communities and to determine the role of race in these observations, we reviewed the patient records of all adults who underwent renal biopsies at our institution over the 20-year period from 1974 to 1994. The patients were grouped for analysis in 5-year intervals, 1975 to 1979, 1980 to 1984, 1985 to 1989, and 1990 to 1994, for the following diagnoses: FSGS, membranous nephropathy (MN), minimal change nephropathy (MCN), membranoproliferative glomerulonephritis (MPGN), immunoglobulin A (IgA) nephropathy, chronic glomerulonephritis, diabetic nephropathy, hypertensive nephrosclerosis, and chronic interstitial nephritis. Patients with secondary causes for these lesions were excluded. The relative frequency of FSGS increased from 13.7% during 1975 to 1979 to 25% during 1990 to 1994 (P < 0.05). The relative frequency of MN decreased from 38.3% during 1975 to 1979 to 14.5% during 1990 to 1994 (P < 0.01). There were no changes in the frequencies of MCN, MPGN, IgA nephropathy, chronic glomerulonephritis, diabetic nephropathy, hypertensive nephrosclerosis, or chronic interstitial nephritis over the 20-year period. However, there was a significant increase in the percentage of blacks with FSGS, from 0% in 1975 to 1979 to 22.6% in 1990 to 1994, and an increased percentage of Hispanics with FSGS, from 0% in 1975 to 1979 to 21.3% in 1990 to 1994 (P < 0.05). The modest increase in whites with FSGS did not reach statistical significance. The incidence of MN in blacks and whites decreased over the 20-year period. In the last 5 years, 15 patients per year had FSGS compared with 7 patients per year with MN (P < 0.05). No changes in age or sex between groups or over time accounted for these results. We conclude that FSGS is now diagnosed twice as often as MN and is the most common idiopathic glomerular disease at our hospital. Reasons for this increase include the emergence of FSGS in both Hispanics and blacks, with a modest increase of FSGS in whites. The increase in FSGS in the three most common races in our community suggests that factors other than genetic, perhaps environmental, have a role in the pathogenesis of FSGS.

Two patients treated with chronic dialysis and renal transplantation developed acute hemorrhage from a native kidney. Bilateral native nephrectomy demonstrated acquired cystic disease and adenocarcinoma in each of the four kidneys. The etiology of acquired cystic kidney disease (ACKD) is unclear and its incidence increases with the duration of dialysis. ACKD patients have a propensity to develop adenomas and adenocarcinomas. The increased incidence of renal neoplasms in ACKD patients warrants careful radiologic monitoring of native end-stage kidneys in selected patients.

Interstitial cystitis, a sterile bladder condition, is characterized by urinary frequency, urgency, burning and suprapubic pain. Increasing evidence indicates that interstitial cystitis is a heterogeneous syndrome that reflects an immune response to a variety of triggers. More than 50% of the patients have allergies, 30% have the irritable bowel syndrome and almost 20% suffer from migraine headaches. Increased numbers of mast cells have been reported in interstitial cystitis. Mast cell activation, which is critical if these cells were to be implicated in this syndrome, has been investigated by electron microscopy, which definitively shows mast cell secretion. Recently, methylhistamine, the major metabolite of histamine, and the specific mast cell marker, tryptase, were shown to be significantly elevated in urine of interstitial cystitis patients. Bladder biopsies from 53 patients were analyzed blindly for the number and degree of activation of mast cells using 4 different stains for light microscopy, as well as electron microscopy. Controls included 16 patients with incontinence and chronic bacterial cystitis. Mast cells in controls were less than 10/mm.2 and were all nearly intact. Surprisingly, mast cells from 11 cancer patients averaged 50/mm.2 but almost all were intact. In contrast, mast cells from 26 interstitial cystitis patients averaged 40/mm.2 and more than 90% were activated to various degrees. Therefore, bladder mast cell activation is a characteristic pathological finding in at least a subset of patients with interstitial cystitis.

The biocompatibility of a new elastomeric-hydrogel matrix biomaterial for use as an intravasal occlusive device was assessed by inserting it into the vas deferens of dogs. The vas was removed and examined histologically after varying periods of time. The biomaterial resulted in total occlusion of the vas. Epithelial changes were limited to squamous metaplasia in areas adjacent to the implant. Changes in the subepithelium were minimal. This new material is biocompatible with the dog vas, and it has potential as an occlusive device for "reversible" vasectomy in men. Semen analysis studies are needed to assess the completeness and reversibility of the vasal occlusion achieved with this implant.

Exclusive reliance on radiographic techniques for the diagnosis of renal angiomyolipoma can lead to misdiagnosis when the histological status is atypical, computerized tomographic findings are equivocal or renal cell carcinoma coexists. We report our experience and those of others in combining fine needle aspiration biopsy and radiological imaging to identify renal angiomyolipoma. Fine needle aspiration biopsy is safe and provides accurate histological diagnosis of renal angiomyolipoma.

Endometriosis involving the muscular wall of the bladder may cause symptoms similar to those of interstitial cystitis. Vesical endometriosis should be considered in the differential diagnosis of interstitial cystitis, especially in patients with a history of prior gynecologic or pelvic surgery.

A renal tumor developing in a patient receiving cyclophosphamide (Cytoxan) therapy for Wegener granulomatosis is reported. The tumor was similar histologically to the "immunoblastic" sarcoma that develops in renal allograft recipients as a complication of immunosuppressive therapy. This case report strengthens the cause and effect relationship between immunosuppressive drug usage and the subsequent development of neoplasia.

Testicular microlithiasis occurring in a postorchiopexy testis is described. The histologic characteristics of this uncommon entity are presented, and its etiology and clinical significance are briefly reviewed.

Accurate preoperative diagnosis of renal angiomyolipomas is essential if conservative resection or angiographic embolization is to be used. Computed tomographic (CT) scanning failed to diagnose angiomyolipoma preoperatively in 2 patients, and this led to a retrospective review of 6 patients to define the limits of CT scanning in preoperative diagnosis. The CT findings were correlated with the histology of the tumors. Two tumors with positive attenuation coefficients suggestive of renal adenocarcinoma had significant amounts of immature "fetal" fat, and one of these had a virtual absence of mature fat. The relative inability of CT scanning to identify immature "fetal" fat, especially in the presence of abundant vessel and muscle elements, is a limitation to its use in the preoperative diagnosis of angiomyolipoma. A negative attenuation coefficient is highly characteristic of renal angiomyolipoma with mature fat elements. A positive attenuation coefficient, although suggestive of renal cell carcinoma, may be found in angiomyolipomas with paucity of mature fat or high proportions of immature fat.

A retrospective review of 6 patients with renal angiomyolipoma treated surgically revealed regional lymph node involvement in 2--an incidence of 33 per cent. The clinical behavior in these patients suggests that nodal involvement is an expression of multicentricity rather than metastatic disease.