Takashi Shimotori

A scanning electron microscope study of the glomerulus of normal and nephritic rabbits

SummaryThe glomerulus of normal and Masugi-nephritic rabbits was studied by scanning electron microscopy. The fundamental structure of the podocyte was essentially the same as that of rats and man. It was characteristic in rabbits that broad cytoplasmic sheets were frequently extended from the cell bodies, which might correspond to “podocytic membrane (Elias)” seen in transmission electron microscopy. In Masugi nephritis of rabbits the podocytes revealed increase in number, irregular arrangement and atrophy of the cytoplasmic processes, and increase of microprojections, which were assumed to be secondary reactions to proliferative glomerulonephritis. The terminal processes were preserved in large parts of glomeruli, although they were irregularly either atrophied or swollen.

A case of endocapillary proliferative glomerulonephritis with macrophages phagocytosing monoclonal immunoglobulin lambda light chain.

Multiple myeloma (MM) is a plasma‐cell neoplasm that can cause renal disorders. Renal lesions in MM can present with a very rare pathological manifestation involving a specific monoclonal immunoglobulin (Ig). We report the case of a 33‐year‐old woman who had edema, fatigue, elevated serum creatinine levels, hypoalbuminemia, and hypercholesterolemia. She had persistent hematuria and proteinuria lasting 3 years. Serum protein electrophoresis showed an M‐spike, and serum immunofixation demonstrated the presence of monoclonal IgG λ. She had proteinuria in the nephrotic range, and a monoclonal λ fragment was present on urine immunofixation. Renal biopsy showed proliferative glomerulonephritis with λ light chain and C3c deposition and inflammatory cell infiltration with CD68. Macrophage lysosomes contained λ light chains, suggesting their partial phagocytosis. She was diagnosed with symptomatic MM and was treated with bortezomib and dexamethasone and an autologous peripheral stem cell transplant conditioned with intravenous melphalan. She achieved a partial response with decreased serum monoclonal protein and improved renal function. This case may be categorized as a monoclonal gammopathy‐associated proliferative glomerulonephritis. The biopsy finding of partially phagocytosed Ig λ light chains by macrophages is very rare; this pathological condition is similar to crystal‐storing histiocytosis.

Classification of chronic glomerulonephritis based on prognostic considerations.

Based on the correlation of LM, EM and IF findings of kidney biopsy tissues with the clinical and laboratory findings as well as renal function, classification of primary GN is proposed with special reference to the smouldering and progressive forms of chronic GN. The two forms of chronic GN should be differentiated because their prognoses are different.