Spectrum of glomerular and tubulointerstitial renal lesions associated with monotypical immunoglobulin light chain deposition.

The purpose of this study was to characterize the spectrum of renal lesions associated with plasma cell dyscrasias from a population of patients who had renal disease identified by kidney biopsy. Thirty-six patients (2.6% of 1361 kidney specimens examined over 6 years) had evidence of monotypical light chain with or without concomitant heavy chain deposition. A variety of lesions was found, including (a) AL-amyloid and glomerular nonamyloid light chain deposition manifesting as nodular, membranoproliferative, mesangioproliferative, and "minimal-change" glomerulopathies; (b) fibrillary glomerulopathy; (c) tubulointerstitial lesions (cast nephropathy, acute tubular necrosis, and tubulointerstitial nephritis); and (d) vascular (arterioles and small and medium-sized arteries) lesions. AL-amyloid was the most common renal lesion (39%), nonamyloid deposition occurred second most commonly (33%), and cast nephropathy ("myeloma kidney") was third most frequent (14%). Clinical and laboratory manifestations of a plasma cell dyscrasia were frequently subtle. Immunoelectrophoresis of both serum and urine did not demonstrate a monotypical light chain or immunoglobulin in almost 35% of this population. Thus, the correct diagnosis was not considered in the majority of these patients before biopsy. Progressive deterioration of renal function was common with all of the lesions, except for proximal tubule injury, which tended to improve over the period of study. Renal biopsy with careful examination for monotypical light chain with or without associated heavy chain deposition using immunofluorescence or immunoelectron microscopy was crucial in identifying and characterizing the varied lesions associated with lymphoplasmacytic disorders.

Ultrastructural immunolabeling in the diagnosis of light-chain-related renal disease.

Renal tissue from eight patients with light-chain deposition disease (LCDD) was immunolabeled for electron microscopy by a postembedding indirect immunogold staining procedure, using anti-kappa and anti-lambda antibodies. This technique provided an exact immunomorphological method to confirm the presence of monotypical light chains in glomeruli, tubules, and vessels. In two cases, it served to prove monotypical light-chain deposition which was not clear upon examination of sections stained for kappa and lambda light chains at the light microscopic level, using PAP or immunofluorescence methods. Three cases of amyloid nephropathy, in which the amyloid deposits stained for monospecific light chains and were immunolabeled ultrastructurally, are also described. LCDD manifests with a variety of morphological patterns in the kidney and the pathological definition of this entity has been difficult. Ultrastructural immunolabeling is a useful method to supplement existing techniques in the diagnosis of LCDD and related conditions. One outstanding feature of the postembedding technique is the ability to examine fixed and preserved renal tissue for the presence of light chains on a retrospective basis.

Acute poststreptococcal glomerulonephritis progressing to rapidly progressive glomerulonephritis.

We have reported a rare, well documented case of poststreptococcal glomerulonephritis followed by rapidly progressive glomerulonephritis after weeks of stable renal function. The patient was successfully treated with steroids, azathioprine, and plasmapheresis. Progression of stable proliferative poststreptococcal glomerulonephritis to rapidly progressive glomerulonephritis appears to be uncommon.

Effects of desoxycorticosterone acetate on magnesium metabolism in potassium-depleted rats.

Metabolic balance studies were performed in two groups of 6 rats each, pair-fed a diet deficient in potassium. While one group was injected with desoxycorticosterone acetate (DOCA) for 11 days, the other group, used as a control, was injected with oil. The administration of DOCA suppressed or reversed the thirst, natriuresis, diuresis, calciuria and magnesiuria that developed in the potassium-deficient control group. Potassium-depleted DOCA-treated rats had a more positive water and sodium balance, experienced a significant expansion in plasma volume, had a more negative potassium balance and had a lower plasma potassium concentration. Magnesium balance decreased in the group fed the diet deficient in potassium and injected with oil but it rose towards control levels in the group fed the same diet and treated with DOCA. As the content of potassium in muscle decreased in rats fed the diet deficient in potassium and injected with oil, the concentration of magnesium in muscle also fell and the plasma concentration of magnesium increased. Thus, the hypermagnesemia of potassium depletion could be explained by the shifting of magnesium from tissue into the extracellular space. The partial compensation of the hypermagnesemia observed in the potassium-deficient group injected with DOCA may be the result of the hemodilution secondary to plasma expansion.

Transurethral passage of Aspergillus fungus balls in acute myelocytic leukemia.

A patient with acute myelocytic leukemia who had a chronic febrile illness during the induction of remission of leukemia developed asymptomatic discrete pulmonary infiltrates which rapidly evolved into cavities containing homogeneous opacities. Over the next five weeks, the cavities resolved without specific treatment. The patient subsequently passed large fungus balls in the urine, and the diagnosis of disseminated aspergillosis was made. A course of intravenous amphotericin B therapy was completed without complications. This case demonstrates the importance of culturing urine specifically for fungal organisms in the immunosuppressed host.

Azathioprine-induced pure red blood cell aplasia.

Pure RBC aplasia developed in two renal transplant recipients who were receiving long-term azathioprine therapy. With substitution of cyclophosphamide therapy for azathioprine, erythroid hyperplasia and reticulocytosis developed at three weeks in one patient and at three months in the other. Selective erythroid toxic reaction is a potential problem that must be considered when anemia develops in patients receiving long-term azathioprine therapy.