ODP295 An Unusual Case of Isolated IgG4 Related Hypophysitis

Abstract

Abstract Introduction Hypophysitis, characterized by chronic inflammation of the pituitary, is a histological diagnosis, secondary to lymphocytic, granulomatous, plasmacytic, necrotizing, or xanthomatous etiology. Infiltration of the IgG4 (Immunoglobulin G4) positive plasma cells, lymphocytes, and subsequent fibrosis lead to IgG4 related hypophysitis. This is typically a part of a multifocal systemic disease called IgG4 related diseases and isolated pituitary involvement is uncommon. Here, we present a case of isolated IgG4 related hypophysitis. Case A 34-year-old woman presented with secondary amenorrhea and galactorrhea. Hyperprolactinemia (137 ng/mL) was noted with no associated pituitary hormone deficits. MRI pituitary showed a markedly enlarged, heterogeneous, diffusely enhancing pituitary gland measuring 13.6×12.8×15.2 mm and a small, non-enhancing focus on the left, abutting the chiasm with mass effect and mild displacement of the stalk. Cabergoline was started with the resolution of galactorrhea and normalization of prolactin levels (<1 ng/mL). MRI pituitary after 18 months of treatment showed enlarging pituitary hyperplasia (11.3×17×14.1 mm). The patient developed worsening headaches and diplopia due to 6th cranial nerve palsy. Infiltrative disorders like sarcoidosis and hemochromatosis were ruled out. She denies any history of radiation therapy, CNS infections, or familial history. Lumbar puncture showed elevated proteins (80 mg/dL) and positive oligoclonal bands of IgG. Transsphenoidal resection of the pituitary mass revealed a fibrous lesion. Pathology revealed lymphoplasmacytic infiltrate consistent with IgG4 hypophysitis. She did not have systemic evidence of IgG4 related diseases. A six-month follow-up MRI showed a recurrent 12×14×13 mm pituitary lesion with a mass effect on the optic chiasm. Prednisone 40 mg daily was started. She developed TIA followed by a stroke within two weeks. Autoimmune labs were positive for speckled ANA 1: 160. High dose methylprednisolone was given for 5 days followed by treatment with 2 doses of rituximab and 4 doses of cyclophosphamide. She showed good clinical response with resolution of the pituitary mass. Discussion IgG4 related hypophysitis refers to non-hormone secreting pituitary inflammation and enlargement that shares clinical and radiological pictures like nonfunctioning pituitary adenomas. Male preponderance is noted with a presentation in the 5 th to 7 th decades of life. The prevalence of IgG4 related hypophysitis is around 30% of hypophysitis but only 1.3% of primary hypophysitis cases with no systemic involvement. Autoimmunity and infectious agents are potential inciting factors in the pathogenesis of IgG4 related diseases. Simple observation is generally recommended if the disease is asymptomatic. If the disease is symptomatic, high-dose glucocorticoids are the first choice in the absence of visual compromise requiring immediate surgical decompression and have shown a favorable response. For steroid-refractory cases, treatment options include Rituximab, azathioprine, cyclophosphamide, surgery, or radiation. Further literature study is required to identify this uncommon etiology. Presentation: No date and time listed