To the Editor:
The aim of this letter is to highlight a clinical phenomenon, insufficiently recognized: the ANCA-positive vasculitis with a subacute evolution. We present a series of five patients with ANCA-positive systemic vasculitis and small-sized kidneys on diagnosis.
All patients were women (mean age 67 years). Two of them had a history of arthralgias, epistaxis, severe anemia and repetitive miscarriages, and one of them had bronchial asthma. The clinical picture began with a constitutional syndrome. In two cases it was accompanied by nicturia and in one by hemoptysis. Mean CRP was 2.4 ± 1.8 mg/dL. Proteinuria in the non-nephrotic range (maximum 1g/24 hours) and microhematuria with deformed red blood cells were present in all patients.
Immunological investigations were negative except for ANCA, which exhibited an anti-myeloperoxidase pattern. On diagnosis, the ultrasound revealed a decreased renal size with a maximal longitudinal axis of 9 cm in all cases. A renal biopsy was performed in 3 patients, which showed vasculitic lesions, sclerosed glomeruli, and intense interstitial fibrosis, obviously related with the diminished renal size. Three patients presented at least one episode of pulmonary hemorrhage, and two patients died from infectious complications. In three cases the condition evolved to end-stage renal disease requiring hemodialysis, while the others were controlled with immunosuppressive drugs. It is interesting that two patients had been diagnosed with nephroangiosclerosis and presented the first episode of pulmonary hemorrhage when they already were on hemodialysis. This episode prompted the ANCA investigation.
The reported cases are remarkable due to the coincidence of small sized kidneys and ANCA-positive vasculitis. In this condition the usual presentation differs, because the renal size is normal or perhaps bigger than normal as a consequence of the inflammatory reaction. Renal vasculitis has usually a rapidly progressive evolution, but it is evident that it sometimes evolves more torpidly, with a slow worsening of renal function and few manifestations on urine sediment (minimal proteinuria of microhematuria, which initially go unrecognized).1 Falk et al. have recently pointed out that the disease can possibly evolve in flares of vasculitis, with progressive glomerular lesions, which can produce a late clinical picture, when more than a half of the glomeruli are affected. In this sense, a glomerulonephritis evolving to CRD should never be considered as a mild condition.2 If the clinical evolution is slow, the episodes of focal necrosis resolve with glomerular scaring and sclerosis, and at each flare new glomerular lesions are added. That could explain the diminution of the renal size.
It is possible that among patients who are on renal replacement therapy with a disease of unknown origin and with small kidneys on diagnosis, some of them may have been diagnosed with nephroangiosclerosis and present, positive ANCA antibodies and vasculitis with few clinical manifestations, being susceptible to suffer from an episode of pulmonary hemorrhage while on hemodialysis program. In this setting, if the diagnosis is not clear, at least an ANCA determination should be mandatory and profitable, to avoid diagnostic failures with important consequences.
