Antithyroid drugs-induced antineutrophil cytoplasmic antibody-associated vasculitis in children: report of three cases and literature review / 中华肾脏病杂志

ABSTRACT

Objective:To explore clinicopathological features and prognosis of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) in children induced by antithyroid drugs.Methods:The clinicopathological features, treatment and prognosis of 3 children with AAV induced by antithyroid drugs in the Department of Pediatric Nephrology and Rheumatology of the First Affiliated Hospital of Sun Yat-sen University were analyzed retrospectively, and the literatures were reviewed.Results:(1) Among the 3 cases, there were 2 females and 1 male, whose ages were 12.6, 13.9 and 13.1 years old, respectively. All patients had medication history of propylthiouracil (PTU) and/or methimazole (MMI) before onset. Initial manifestation was pallor and renal involvements with nephrotic proteinuria, hematuria and renal function abnormality, while 2 of them had hypertension. Extrarenal manifestations were also presented case 1 presented with rash, arthralgia and cardiac insufficiency; case 2 had brain involvement with repeated convulsions; case 3 presented with arthralgia and lung involvement. They were all tested positive for p-ANCA and MPO-ANCA. Initial renal histopathology of the 3 cases were consistent with ANCA-associated glomerulonephritis, which were classified into sclerosis, crescentic and mixed class respectively. After 8 months of treatments, repeated renal biopsy of case 3 had demonstrated progression to sclerosis class. Antithyroid drugs (PTU or MMI) were discontinued in 3 cases, and the children were all treated with corticosteroid combined with intravenous pulse cyclophosphamide therapy. Plasma exchange was performed in case 2 and case 3 due to rapidly progressive glomerulonephritis and disease recurrence (suspected pulmonary hemorrhage), respectively. Case 3 was treated with rituximab combined with mycophenolate mofetil after recurrence. The extrarenal symptoms relieved quickly after treatments in all cases. P-ANCA and MPO-ANCA became negative in case 1 and case 2 after 6 months of treatments but they were persistently positive in case 3. Three cases were followed up for 24 months, 10 months and 12 months, respectively case 1 develop chronic kidney disease (CKD) stage 2 with normal urinalysis; case 2 develop CKD stage 5 and had sudden death at home at 10-month follow-up; case 3 develop CKD stage 4 with nephrotic proteinuria and microscopic hematuria. (2) There were totally 30 pediatric cases with AAV induced by PTU and MMI, including 27 reported cases in the literature and 3 cases in this study. Symptoms of AAV appeared in children after an average administration of (37.5±4.0) months of PTU (range from one month to 96 months and 8 months of MMI alone). Kidney (28 cases, 93.3%) and lung (12 cases, 40.0%) were commonly involved, while brain (2 cases, 6.7%) was rarely involved. The pathological changes of kidney were crescent nephritis (5/23) and necrotizing pauci-immune complex nephritis (11/23). The total remission rate was 93.3% (28/30) after antithyroid drugs withdrawal and treatment with corticosteroids and immunosuppressive therapy, however, there were still severe cases with progression to CKD stage 5, and death. (3) Thirty cases were divided into complete response group ( n=19) and incomplete response group ( n=11) according to the treatment response. Compared with complete response group, the proportions of massive proteinuria (8/11 vs 5/19), fibrinoid necrosis (7/9 vs 4/14), deposition of immune complex in renal tissues (6/9 vs 2/14) and administration of immunosuppressants (10/11 vs 5/19), and degree of tubular atrophy (0/1/2/3 grade, 2/4/2/1 vs 9/5/0/0) in incomplete response group were higher (all P<0.05). Conclusions:PTU and MMI can both induce AAV in children, and AAV may occur after short-term course of administration. Kidney and lung are commonly involved while brain involvement is rarely seen. Timely withdrawal of antithyroid drugs and proper treatments with corticosteroids and immunosuppressants can result in high remission rate, though there are still some severe cases. Nephrotic-range proteinuria, renal fibrinoid necrosis, immune-complex deposition and tubular atrophy may be the risk factors of AAV for poor prognosis.