MORPHOLOGY OF RECURRENT DENSE DEPOSIT DISEASE IS NOT TYPICAL OF NATIVE DISEASE: A REPORT OF TWO CASES.

D. F. Griffiths,  S M. Howarth,  J. Chess,   R. Ravanan.

Departments of Pathology and Nephrology; Cardiff and Vale NHS Trust, Cardiff,  CF14 2DX, United Kingdom.     Email for correspondence:  griffithsdfr@cf.ac.uk

Introduction

Dense deposit disease (DDD) commonly recurs in renal allografts; this may result in graft failure and the correct diagnosis has important implications for immediate treatment and management of subsequent grafts.  We present two cases that illustrate the varied morphology, one of which was treated by rituximab.

Case 1 Female with renal failure due to DDD at 11 yrs age had a renal allograft at 18 yrs age and was treated with standard triple therapy (Tac, MMF and Pred)  She suffered biopsy proven acute cellular rejection at 3 months, treated successfully with pulsed IV steroids, to give a stable creatinine of about 120mmol/L. At 14 months an acute increase in creatinine was investigated by renal biopsy.  Histology showed an acute diffuse endocapillary glomerulonephritis with no GBM abnormality on silver stain and no interstitial inflammation.  C3 was present on capillary loops and electron microscopy (EM) showed typical linear dense deposit.  Treatment with plasmapheresis resulted in poor but stable renal function (creatinte180 mmol/L) for the next 6 months

Case 2  Female with renal failure due to DDD at 20 yrs age had a cadaveric renal allograft at 23 yrs with Tac and MMF as primary immunosupression.  After good initial function, a biopsy at 3 weeks for secondary dysfunction showed glomerular intracapillary thrombus only.  Biopsy at 7 weeks showed an acute focal segmental proliferative GN without significant scaring or tubulo-interstital changes.  The GBMs were normal on silver stain; however on EM linear dense deposits were seen.  Treatment with plasmapheresis and rituximab [2 doses of 375mg/m²] resulted in clinical recovery and a protocol biopsy carried out at 28 weeks showed focal segmental sclerosis with no active lesions and considerable resolution of the dense deposit at EM.  At 38 weeks glomerular relapse resulted in further decline in renal function. 

Conclusions

Recurrent DDD rarely presents with classical membranoproliferative histological pattern; while diffuse endocapillary GN has been previously described; intracapillary thrombi and a focal segmental proliferative GN appear to be a novel finding.  This variety of morphologies emphasises the importance of electron microscopy.  Initial success, including histological resolution, with rituximab is encouraging; further assessment of this treatment can only be made on a multicentre basis.