Diagnosing ANCA-associated vasculitis in children and adolescents can pose difficulties for doctors, given its rarity and varied clinical course, researchers say.
In a new study, investigators described the case of a teenager with MPO-positive vasculitis and severe pulmonary and renal symptoms, who went without a diagnosis for about four years.
The study, “The Diagnosing Challenge of a Positive ANCA Vasculitis in the Paediatric Age,” was published in Case Reports in Pediatrics.
Diagnosing anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is challenging in anyone, but especially in patients without a typical clinical presentation and disease progression.
Researchers at Centro Hospitalar do Porto, in Portugal, described a teenager who for years exhibited several AVV symptoms associated with different disease subtypes.
At 11 years old, the girl began having episodes of respiratory distress — wheezing, coughing, and stridor (a high sound emitted when breathing, linked to obstruction) — that led to multiple hospitalizations. Evaluations ruled out allergies, pulmonary infections, or cystic fibrosis as potential causes.
After turning 12, her voice progressively became more hoarse, and she did not respond to corticosteroid treatments. Physical exams revealed that the soft tissues of her windpipe were unusually stiff. She underwent surgery but later had to be intubated due to respiratory insufficiency.
Blood analysis was negative for ANCA autoantibodies. Yet, she had increased levels of blood cells and proteins in the urine and mild changes in renal function.
When she was 14 her renal condition worsened. At this point, test results for ANCA antibodies came back positive for anti-MPO antibodies. Four months later, at age 15, her condition had considerably deteriorated, with abdominal pain, vomiting, diarrhea, difficulty in breathing, and coughing. She showed signs of fluid retention, hypertension, severe anemia, and kidney problems.
The girl was transferred to the intensive care unit for children to give respiratory and renal support. Her condition was re-evaluated, and confirmation of her renal and pulmonary symptoms in addition to the positive anti-MPO antibodies test, led the team to diagnose MPO-ANCA-positive vasculitis. Treatment with corticosteroids and supportive therapies was initiated.
“In this case, the diagnosis was even more difficult since the serologies [blood analysis] were initially negative, and the child was monitored in different centres which may have hampered the clinical data integration,” the researchers said.
Because of the delay in treatment, the girl developed end-stage kidney disease requiring dialysis. Still, her general condition improved. Within six months, she regained her voice and anti-MPO levels dropped to within normal range.
“There is little knowledge about the optimal treatment of AAV patients who developed severe renal insufficiency,” the researchers said. “These patients have less probability of responding to therapy compared with preserved renal function patients and additionally present an increased risk for immunotherapy adverse effects.”