MON-069 - Igg4-Related Hypophysitis with Normal Serum Igg4: Expanding the Diagnostic Spectrum

Background/

Objective:
IgG4-related hypophysitis is a rare manifestation of the systemic fibroinflammatory IgG4-related disease spectrum, characterized by lymphoplasmacytic infiltration, storiform fibrosis, and IgG4-positive plasma cells in the pituitary gland. This case illustrates the importance of a multifaceted approach in diagnosing IgG4-related hypophysitis and raises the possibility that other IgG subclasses may contribute to variants of this elusive disease.

Case Presentation:
A 32-year-old woman presented with a 1-year history of new and progressively worsening headaches, vomiting, and visual disturbances, associated with amenorrhea and galactorrhea. Magnetic resonance imaging of the brain showed a heterogeneously enhancing lesion in the sella turcica measuring 1.7 x 1.3 x 1.6 centimeters extending into the corpus callosum and cavernous sinuses. Transsphenoidal resection revealed chronic and acute hypophysitis with focal storiform fibrosis and necrosis, consistent with IgG4-related disease after staining identified 46 cells per high-power field. Total serum IgG concentration was normal at 1270 mg/dL (reference range 562-1631 mg/dL), though IgG2 was elevated at 618 mg/dL (reference range 124-549 mg/dL) and IgG4 was normal at 7 mg/dL (reference range 1-8 mg/dL). Corticosteroids initially produced radiographic and symptomatic improvement, but temporary medication discontinuation led to ophthalmic manifestations requiring rituximab. She also developed central diabetes insipidus, central adrenal insufficiency, and central hypothyroidism.

Discussion:
In addition to IgG4, other IgG subclasses may contribute to the pathogenesis of IgG4-related disease, and emerging evidence supports the use of non-corticosteroid therapies in the treatment of refractory IgG4-related hypophysitis.

Conclusion:
Despite proposed diagnostic frameworks, definitive diagnosis of IgG4-related hypophysitis remains challenging without histopathologic confirmation, and effective treatment may include therapies beyond corticosteroids in steroid-resistant cases.

Key Words:
IgG4-related disease, hypophysitis, IgG2, ophthalmic disease

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