Testing positive for anti-PR3 antibodies and showing lesions in the lungs and cartilaginous tissues could replace nasal biopsy for diagnosing patients with suspected granulomatosis with polyangiitis (GPA) and chronic rhinosinusitis, according to a pilot study.
The study, “Should nasal biopsy inevitably be performed for classifying granulomatosis with polyangiitis in patients with rhinosinusitis? A retrospective chart review study,” appeared in the journal Rheumatology International.
GPA is a subtype of ANCA-associated vasculitis that mainly affects the upper and lower respiratory tracts. Ear, nose, and throat involvement occurs initially in most GPA patients, with chronic rhinosinusitis — inflammation of the sinuses and nasal cavity — being its most frequent manifestation.
Because rhinosinusitis could result from other conditions, a nasal biopsy is usually performed to determine whether these patients have GPA. However, the procedure may not be possible for patients in poor medical condition. As a result, a team at Yonsei University College of Medicine in South Korea assessed clinical manifestations and laboratory parameters that could help detect GPA when a nasal biopsy cannot be done.
The investigators reviewed the medical records of 45 patients with GPA, with a mean age at diagnosis of 58.4 years, all of whom had not received any immunosuppressants before their diagnosis.
Twenty-five patients had chronic rhinosinusitis, 16 of whom underwent a nasal biopsy. Of these 16 patients, eight had anti-PR3 antibodies and four showed anti-MPO antibodies.
The team then tested different criteria to reclassify GPA in patients with chronic rhinosinusitis. Specifically, in three of six patients, all without evidence of granuloma — inflammation characterized by clusters of macrophages — but with ANCA antibodies, using both the 2007 European Medicines Agency (EMA) algorithm and the 2012 Chapel Hill Consensus Conferences Nomenclature of Vasculitis, could also lead to a classification of microscopic polyangiitis (MPA).
Using the 2017 American College of Rheumatology/European League Against Rheumatism provisional classification criteria in three patients with chronic rhinosinusitis and without granuloma on nasal biopsy confirmed the initial GPA diagnosis. This was due to having both rhinosinusitis and anti-PR3 antibodies.
Nine other patients with chronic rhinosinusitis who did not undergo nasal biopsy had ANCA antibodies and GPA surrogate markers such as chronic sinusitis and subglottic stenosis — narrowing of the airway below the vocal cords. This means they could be classified as GPA based on both the 2007 EMA algorithm and the 2017 ACR/EULAR criteria.
“Therefore, we concluded that PR3-ANCA (or C-ANCA) may be a strong factor suggesting GPA and it could replace nasal biopsy in GPA-suspected patients with chronic rhinosinusitis,” the scientists wrote.
Then, excluding granuloma on nasal biopsy as a factor meant that four of 10 patients with chronic rhinosinusitis could no longer be classified as GPA based on the 2007 EMA algorithm, because they did not have ANCA antibodies. However, all four patients still fulfilled the 2017 ACR/EULAR criteria, since two had lung lesions on chest imaging and the other two had lesions in cartilaginous tissues.
“Therefore, we also concluded that GPA-specific cartilaginous involvement may be a strong factor suggesting GPA as much as lung lesions,” the team added.
Still, in cases with lung lesions not specific for GPA, when lung biopsy is not recommended, or there are no cartilaginous lesions, the researchers recommend a nasal biopsy to differentiate between MPA and GPA, as well as to identify early GPA, localized GPA, and ANCA-negative GPA “until the 2017 ACR/EULAR provisional criteria are not fully established.”