[Glomerulopathy associated with glomerular microtubular deposits: a report of a case]

A male aged 58 was admitted to our hospital because of proteinuria, hematuria and bilateral pretibial edema. Laboratory tests showed normocytic, normochromic anemia and moderately impaired renal function. Antinuclear antibodies were negative. Neither M-protein nor Bence-Jones protein were detected. Light microscopic study on the biopsied renal specimen indicated a moderate mesangial proliferation accompanying with the deposition of PAS-positive and Congo red-negative materials in the subendothelial area. C3 accumulated segmentally along the capillary walls, which was clarified by immunofluorescence microscopy. Staining for IgG, IgA, IgM and light chains were negative. Electron microscopy demonstrated the deposition of microtubules in the mesangial, subepithelial and subendothelial areas. The diameter of these microtubules ranged from 40 to 80 nm. Such type of the microtubules have been reported to exist in the glomeruli in the patients with systemic diseases such as amyloidosis, systemic lupus erythematosus, cryoglobulinemia and light chain disease. In our patient, however, any clinical or serological findings suggestive of these systemic diseases were not obtained. On the other hand previous report pointed out that microtubules deposited in the glomeruli in the patients with immunotactoid glomerulopathy or other glomerulopathies. Our patient had the clinical features consistent with these glomerulopathies. However, no depositions of immunoglobulins were observed. This case is an atypical glomerulopathy accompanying with the glomerular microtubular deposits.