Patients with ANCA-associated vasculitis producing PR3-ANCA antibodies may have inadequate blood delivery to internal organs, such as the kidneys and spleen, leading to organ malfunction and pain, a case report suggests.
The study, “PR3 vasculitis presenting with symptomatic splenic and renal infarction: a case report and literature review,” was published in BMC Nephrology.
ANCA-associated vasculitis is a condition characterized by the production of self-reactive antibodies – anti-neutrophil cytoplasm antibodies, or ANCAs – that attack a type of immune cell, called neutrophils, leading to damage of small blood vessels.
The most common ANCAs target one of two proteins present in healthy neutrophils: proteinase 3 (PR3) and myeloperoxidase (MPO).
Severe cases of ANCA vasculitis can lead to infarctions — when the organs do not receive enough blood, causing tissue to die — in internal organs such as the kidneys. In most cases, this phenomenon is mild and patients have no symptoms, but researchers at the Royal Berkshire Hospital in the U.K. are now reporting the case of a 19-year-old Caucasian woman who went to the hospital with back, joint, and muscle pain, and a recurrent fever as a result of this condition.
The woman had no previous relevant medical history and reported no family history of renal disease. The only medication she was taking were contraceptive pills to control heavy menstrual bleeding.
The first examination showed normal kidney function, elevated inflammatory markers, and protein and blood in the urine; the latter was associated with menstruation that had finished 24 hours before her visit to the hospital.
She was diagnosed with a urinary infection and discharged with oral antibiotics.
After one week, she returned to the hospital because she was still experiencing the previous symptoms and also had itchy eyes and cough.
A urine test showed that creatinine — a marker of kidney function — had increased since the previous analyses, although it remained within normal range. She was discharged with a diagnosis of a viral infection.
She then went to the hospital a third time because her symptoms had worsened and she now had nausea and bleeding in her fingernail beds.
Her blood tests showed impaired kidney function and increased white blood cells and platelets. She was admitted to the hospital and treated with broad-spectrum intravenous antibiotics.
Further examination showed high levels of ANCAs against PR3, suggesting granulomatosis with polyangiitis (GPA), a type of ANCA vasculitis.
A computed tomography angiogram (imaging of blood vessels and other tissues) showed that her large blood vessels were healthy, but that she had infarctions in the small and middle vessels supplying the kidneys and spleen. A kidney biopsy showed areas of dead tissue.
She was finally diagnosed with GPA with a presence of PR3 antibodies involving small and medium vessels. She started treatment with high-dose corticosteroids and Rituxan (rituximab) — an immunosuppressant — two days after receiving the diagnosis.
She also received anticoagulants, which are not a conventional treatment for ANCA vasculitis, but her doctors considered it necessary to avoid further internal organ damage.
Renal function continued to decrease during the treatment until reaching a plateau. At this point, the patient was discharged.
A medical visit made one month after the final discharge and four months after the initial visit showed that the patient had achieved remission and her markers for kidney function were improving.
“In the case reported here, the patient reported flank and back pain as the predominant presenting complaint, which probably represented symptomatic renal and splenic wedge infarction and was initially misdiagnosed as a urinary tract infection,” the researchers said.
They concluded that “in patients with vasculitis who present with flank or back pain, infarction of abdominal organs should be considered.”