Xanthomatous Hypophysitis in Systemic Rheumatic Disease

Xanthomatous hypophysitis (XH), reported as the rarest etiology of primary hypophysitis, causes inflammation of the pituitary gland.¹ XH may represent a spectrum of autoimmunity and has been seen concomitantly with rheumatoid arthritis (RA).² XH presents with headaches, visual disturbances, and endocrinopathies.³ Case reports document steroid responsiveness in XH, but more recent literature suggests disease stabilization with mycophenolate mofetil raising question of immunologic basis of disease.⁴ We present a case of a 34-year-old female with seropositive RA and granulomatosis with polyangiitis (GPA) well controlled on rituximab and prednisone five milligrams daily presenting with headaches, visual defects, and suprasellar mass on CT. MRI revealed enhancing sellar mass with suprasellar extension. She underwent successful endoscopic transsphenoidal pituitary mass resection. Pathology revealed foamy xanthomatous histiocytes with positive CD68 signature. This represents the first report known to us of XH in both GPA and RA speaking to potential autoimmune relationship and insight into immunosuppressive treatment.