A clinicopathological study of C1q nephropathy at King Abdulaziz University.

INTRODUCTION: C1q nephropathy is a relatively rare idiopathic glomerulopathy characterized by mesangial immunoglobulin and complement deposits with dominance or co-dominance of C1q, with no evidence of systemic lupus erythematosus. We describe the incidence, clinical manifestation, histopathological features, and follow-up of patients with C1q nephropathy at our institute.

MATERIALS AND METHODS: Of 750 kidney biopsy specimens obtained in the period of January 2000 to December 2011, all the cases that meet the criteria for the diagnosis of C1q nephropathy were retrieved.  The histological slides were examined and the clinical charts were reviewed by 2renal pathologists.

RESULTS: We had 11 patients, all children, that met the criteria for the diagnosis of C1q nephropathy accounting for an incidence of 1.5%.  The mean age at the time of presentation was 3.7 years and all the patients were presented with nephrotic syndrome. Two patients had microhematuria and 2 had hypertension. Histological examination of these cases showed variable degrees of mesangial cells hypercellularity and matrix expansion with focal segmental glomerulosclerosis observed in 2 cases. Nine patients were steroid resistant (82%) and 2 were steroid dependent. Six patients required immunosuppressive therapy and 1 patient developed end-stage renal disease.

CONCLUSIONS: In our series, C1q nephropathy affected predominantly young children. Mesangioproliferative pattern was the most frequent histopathological finding in these patients. Clinically, despite steroid resistance, the patients had a relatively good outcome; the worst prognostic outcome was associated with collapsing glomerulopathy.