Infiltrative lymphocytic hypophysitis successfully treated with rituximab and mycophenolate mofetil

Summary: Lymphocytic hypophysitis is a rare neuroendocrine disease characterised by an autoimmune inflammatory disorder of the pituitary gland. We report a 50-year-old woman who presented with headaches and bilateral sixth cranial nerve palsies. MRI of the pituitary revealed extensive fibrosis involving the sellar and extending into both cavernous sinuses causing bilateral occlusion of the internal carotid arteries (ICA). Transphenoidal biopsy confirmed the diagnosis of infiltrative fibrotic lymphocytic hypophysitis. Symptoms resolved with high dose of oral steroids but relapsed on tapering, requiring several treatments of i.v. pulse steroids over 8 months. Rituximab combined with mycophenolate mofetil was required to achieve long-term symptom relief. Serial MRI pituitary imaging showed stabilisation of her disease without reduction in sellar mass or regression of ICA occlusion. The patient's brain remained perfused solely by her posterior circulation. This case demonstrates an unusual presentation of a rare disease and highlights a successful steroid-sparing regimen in a refractory setting.

Learning points: Lymphocytic hypophysitis is a rare inflammatory disorder of the pituitary gland. In exceptional cases, there is infiltration of the cavernous sinus with subsequent occlusion of the internal carotid arteries. First-line treatment of lymphocytic hypophysitis is high-dose glucocorticoids. Relapse after tapering or discontinuation is common and its use is limited by long-term adverse effects. There is a paucity of data for treatment of refractory lymphocytic hypophysitis. Goals of treatment should include improvement in symptoms, correction of hormonal insufficiencies, reduction in lesion size and prevention of recurrence. Steroid-sparing immunosuppressive drugs such as rituximab and mycophenolate mofetil have been successful in case reports. This therapeutic combination represents a viable alternative treatment for refractory disease.

Keywords: 2020; Adult; Angiography; Australia; Autoimmune hypophysitis; Azathioprine; Cholecalciferol; Diplopia; Female; Glucocorticoids; Gonadotrophins; Gonadotropins; Haematoxylin and eosin staining; Headache; Histopathology; Hyperprolactinaemia; Hypogonadism; Hypogonadotrophic hypogonadism; July; MRI; Methylprednisolone; Mycophenolate mofetil*; Novel treatment; Ocular motility testing*; Pituitary; Prednisone; Prolactin; Rituximab; Sixth nerve palsy; Steroids; Transsphenoidal biopsy*; Visual disturbance; White.