Collapsing glomerulopathy as a complication of interferon therapy for hepatitis C infection.

We present the case of a patient with chronic hepatitis C and diabetes, who rapidly progressed to end stage renal disease upon initiation of IFNalpha therapy for his HCV infection. A kidney biopsy revealed advanced collapsing glomerulopathy.

Renal allograft biopsies in the era of C4d staining: the need for change in the Banff classification system.

C4d immunostaining in the peritubular capillaries (PTC) is a marker of antibody-mediated rejection (AMR). We evaluated the histopathologic diagnoses of 388 renal transplant biopsies since the implementation of routine C4d immunostaining at our center. Of these, 155 (40%) biopsies had evidence of acute cellular rejection (ACR), out of which 119 (77%) had pure ACR, 31 (20%) had ACR with concomitant features of AMR, and five (3%) had ACR with focal C4d staining. Sixty-four (16%) biopsies exhibited features of AMR [33 (52%) pure AMR, and 31(48%) concomitant AMR and ACR]. One hundred and fifty-five (40%) biopsies had features of interstitial fibrosis and tubular atrophy (IFTA). Of these, 20 (13%) had concomitant AMR [13 (8.5%) had pure AMR and seven (4.5%) had concomitant ACR and AMR]. Creatinine at the time of biopsy was higher in patients with mixed ACR and AMR and the clinical behavior of mixed lesions is more aggressive over time. Despite having a lower serum creatinine at the time of biopsy, patients with IFTA experienced gradual decline in graft function over time. The pathologic findings in renal allograft biopsies are often mixed and mixed lesions appear to have more aggressive clinical behavior. These findings suggest the need for change in the Banff classification system to better capture the complexity of renal allograft pathologies.

C4d peritubular capillary staining in chronic allograft nephropathy and transplant glomerulopathy: an uncommon finding.

The true incidence of positive C4d staining in the peritubular capillaries of biopsies with chronic allograft nephropathy (CAN) and transplant glomerulopathy (TGP) remains controversial. We retrospectively reviewed all transplant biopsies performed at Saint Louis University Hospital between June 2002 and May 2004. We examined the incidence of positive C4d staining in the peritubular capillaries of biopsy specimens with pure CAN with or without features of TGP. We identified 54 biopsies in 43 patients showing CAN. The average age was 46 +/- 13 years. The average creatinine at the time of biopsy was 308 +/- 211 micromol/l (3.5 +/- 2.4 mg/dl). Twenty (37%) biopsies exhibited features consistent with TGP. Only two biopsies had positive C4d staining in the peritubular capillaries. The C4d positive biopsies were from two different patients; one patient had donor specific antibodies (DSA) against HLA class 1 at the time of biopsy and the other patient had no detectable DSA. None of the TGP biopsies showed peritubular C4d staining. C4d staining of the peritubular capillaries appears to be rare in patients with pure CAN with and without TGP features.

Diabetic glomerulopathy: unusual patterns and dual disease.

Diabetic glomerulopathy is a well-recognized consequence of both type I and type II diabetes. Occasionally, pathologic diagnosis may be challenging for the pathologist. These circumstances include atypical light microscopy or diabetic change with a second superimposed glomerulopathy (dual disease). We have compiled a selection of 12 renal biopsies from diabetic patients that show either an unusual pattern of nephropathy or "dual disease," as well as 2 cases in which the patient had no history of diabetes but had renal biopsies exhibiting changes consistent with diabetic nephropathy. The salient diagnostic features are discussed. To accurately assess these biopsies, immunofluorescence and electron microscopy become essential, and a broadened differential diagnosis must be considered.