Pituitary involvement in ANCA-associated vasculitis: a retrospective single-center experience and literature review

To describe the clinical manifestations and outcomes of pituitary involvement in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). This study evaluated pituitary hormone and imaging in patients with AAV involving pituitary treated at a tertiary hospital from October 2004 to June 2024. Eighteen patients were enrolled, with a mean age of 46.7 ± 15.6 years and a female predominance (13/18). Headache was the most frequent initial symptom (10/18). The predominant pituitary dysfunction included secondary hypogonadism (10/17) and central diabetes insipidus (CDI, 10/18), with the most common MRI finding being loss of posterior pituitary hyperintensity on T1-weighted imaging (16/18). According to the 2022 ACR/EULAR classification criteria, diagnoses included granulomatosis with polyangiitis (GPA, 11/18) and microscopic polyangiitis (MPA, 1/18), with 6 unclassifiable cases. All but one patient tested positive for ANCA. Sellar biopsies performed in 7 cases, with 2 initial misdiagnoses of lymphocytic hypophysitis (LYH). All patients received corticosteroids in combination with immunosuppressive agents or rituximab, which were effective in most patients. Among 11 patients with median 20-month follow-up (range: 8.5–52.0), no cases demonstrated pituitary functional recovery, while disease recurrence occurred in 5 patients. Eighty-seven cases from the literature were included, mainly GPA and one case of MPA. In contrast to the more common recovery of anterior pituitary function in patients with LYH, 15 out of 60 patients with AAV involving the pituitary demonstrated resolution or improvement of CDI during follow-up. Diagnosing pituitary-involved AAV is challenging. Sellar biopsies with atypical features require careful interpretation. Regular systemic evaluation and repeated ANCA testing are crucial for accurate diagnosis.