Antiphospholipid syndrome (APS) nephropathy in catastrophic, primary, and systemic lupus erythematosus-related APS.

OBJECTIVE: Renal involvement in antiphospholipid syndrome (APS) has been poorly recognized. A renal small-vessel vasculopathy, defined as APS nephropathy, has recently been observed in small series of patients with primary APS (PAPS) and systemic lupus erythematosus (SLE)-APS. We examined the renal histologic, clinical, and laboratory characteristics of different groups of patients with APS including catastrophic APS (CAPS).
METHODS: Our study included all CAPS (n=6), PAPS (n=8), and SLE-APS (n=23) patients with biopsy-proven renal involvement who were referred to our departments. The kidney biopsy specimens were retrospectively examined by the same renal pathologist. APS nephropathy was diagnosed as previously described. Demographic, clinical, and laboratory data were recorded.
RESULTS: All patients with CAPS had acute and chronic renal vascular lesions compatible with diagnosis of APS nephropathy. Thrombotic microangiopathy (TMA), the acute lesion, was observed in all CAPS patients. Fibrous intimal hyperplasia of interlobular arteries (FIH) and focal cortical atrophy (FCA) were the most common chronic vascular lesions, occurring in 4 of 6 (66.7%) and 3 of 6 (50%) patients with CAPS, respectively. TMA was detected in 3 of 8 (37.5%) patients with PAPS and in 8 of 23 (35%) patients with SLE-APS, while FIH and FCA were found with similar frequencies in all 3 groups. Hypertension, proteinuria, hematuria, and renal insufficiency were the most common renal manifestations of all APS groups.
CONCLUSION: Acute and chronic APS nephropathy lesions were detected in all 3 APS groups. Acute lesions were more prominent in CAPS, while chronic lesions were found with similar frequencies in all groups. Hypertension, proteinuria, hematuria, and renal insufficiency were the most common renal manifestations of all APS groups.