Early recurrence of dense deposit disease with marked endocapillary proliferation after renal transplantation

Dense deposit disease (DDD), also known as type II membranoproliferative glomerulonephritis (MPGN), is characterized by the presence of continuous intramembranous dense deposits. At present, the histogenesis of DDD is not well known. Reported herein are two cases of early recurrence of DDD in renal allografts, with marked endocapillary proliferation. In case 1 the first allograft biopsy revealed electron-dense deposits mainly in the subendothelial and mesangial areas along with subepithelial humps, but a continuous intramembranous deposition was not obvious. In the sequential biopsy, the deposits were more often seen in the intramembranous area and finally formed a continuous osmiophilic substance, which is a characteristic feature of DDD. In case 2, continuous intramembranous deposition already coexisted with endocapillary proliferation at the first biopsy. In both cases, endocapillary proliferation was alleviated slightly as time progressed. The present report suggests that endocapillary proliferative glomerulonephritis is the earliest lesion in some cases of DDD. Detailed review of a clinical history and a subsequent follow-up biopsy should be done to distinguish these lesions from other types of endocapillary proliferative glomerulonephritis.