C1q nephropathy is a distinct entity characterized by extensive and dominant C1q mesangial deposition with associated steroid resistant proteinuria in the absence of systemic lupus erythematosus. Several morphological patterns ranging from very subtle glomerular alterations to focal/segmental glomerulosclerosis and mesangial proliferative changes have been described. Interstitial nephritis secondary to BK polyomavirus is a recently recognized complication in kidney transplant recipients. It may be associated with a tubulitis-like picture, mimicking sometimes acute tubular rejection. We report the case of a kidney pancreas transplant recipient who developed de novo C1q nephropathy, in the setting of BK polyomaviral interstitial nephritis. He presented with renal allograft dysfunction and a kidney biopsy was performed. It was interpreted as acute cellular rejection. C1q deposits were detected by immunofluorescence studies and electron microscopy. The patient did not respond clinically to appropriate anti-rejection treatment and a second renal biopsy was performed. The possibility of an interstitial nephritis secondary to BK polyomavirus mimicking rejection was suggested. Special immunohistochemical and blood/urine PCR studies for BK virus were performed, confirming the diagnosis of BK virus tubulonterstitial nephritis with a persistent, probable BK virus induced C1q nephropathy.

Jennette JC, Hipp CG: C1q nephropathy: A distinct pathologic entity usually causing nephrotic syndrome. Am J Kidney Dis 1985;2:103–110.
Jennette JC, Hipp CG: Immunopathologic evaluation of C1q in 800 renal biopsy specimens. Am J Clin Pathol 1985;83:415–420.
Iskandar SS, Browing MC, Lorentz WB: C1q nephropathy: a pediatric clinicopathologic study. Am J Kidney Dis 1991;18:459–465.
Nishida M, Kawakatsu H, Komatsu H, Ishiwari K, Tamai M, Sawada T: Spontaneous improvement in a case of C1q nephropathy. Am J Kidney Dis 2000;35:E22.
Sato K, Kudo K, Sakurada T, Yuda F, Sato H, Saito T: Case of glomerular nephritis with C1q uniquely deposited in the mesangial region. Nippon Naika Gakkai Zasshi 1999;88:1518–1520.
Srivastava T, Chadha V, Taboada EM, Alos US: C1q nephropathy presenting as rapidly progressive crescentic glomerulonephritis. Pediatr Nephrol 2000;14:976–979.
Nebuloni M, Tosoni A, Boldorini R, Monga G, Carsana L, Bonetto S, Abeli C, Caldarelli R, Vago L, Costanzi G: BK virus renal infection in a patient with the acquired immunodeficiency syndrome. Arch Pathol Lab Med 1999;123:807–811.
Nickeleit V, Hirsh HH, Binet IF, Gudat F, Prince O, Dalquen P, Thiel G, Mihatsch MJ, Hirsch H: Testing for polyomavirus type BK DNA in plasma to identify renal-allograft recipients with viral nephropathy. N Eng J Med 2000;342:1309–1315.
Nickeleit V, Hirsh HH, Binet IF, Gudat F, Prince O, Dalquen P, Thiel G, Mihatsch MJ: Polyomavirus infection of renal allograft recipients: From latent infection to manifest disease. J Am Soc Nephrol 1999;10:1080–1089.
Howell DN, Smith SR, Butterly DW, Miller Sara E: Diagnosis and management of BK polyomavirus interstitial nephritis in renal transplant recipients. Transplantation 1999;68:1279–1288.
Marshall J, Smith AE, Cheng SH: Monoclonal antibody specific for BK virus large-T-antigen allows discrimination among the different papovaviral large-T-antigens. Oncogene 1991;6:1673.
Jennette JC, Wilkman JC, Hogan SL, Falk RJ: Clinical and pathological features of C1q nephropathy (C1qn). J Am Soc Nephrol 1999;10:1090–1094.
Andresdottir MB, Assmann KJM, Hilbrands LB, Wetzels JFM: Type I membranoproliferative glomerulonephritis in a renal allograft: A recurrence induced by a cytomegalovirus infection? Am J Kidney Dis 2000;35:1–7.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.