IgG4-related hypophysitis diagnosed by retroperitoneal mass biopsy in a patient presenting with abducens nerve palsy: A case report (CARE-compliant article).

RATIONALE Immunoglobulin G4 (IgG4)-related hypophysitis is a rare disorder which often requires invasive pituitary gland biopsy to confirm its diagnosis. We present a case whereby peripheral organ lesion biopsy and imaging findings were sufficient for the diagnosis. PATIENT CONCERNS A 77-year-old man with diplopia was referred to our department by an opthomologist who had diagnosed the patient with right abducens nerve palsy. DIAGNOSES Head magnetic resonance imaging revealed enlargement of the pituitary gland and pituitary stalk, while hormonal analysis revealed panhypopituitarism, thereby indicating a diagnosis of hypophysitis. Abdominal computed tomography imaging revealed a solid mass that encompassed the left kidney ureter. Although the patient did not have an increase in serum IgG4, a biopsy of the periureteral mass revealed infiltrating plasma cells that were positive when stained for IgG4. INTERVENTIONS The patient was given corticosteroid pulse therapy (methylprednisolone: 1 g × 3 days), followed by oral corticosteroids (prednisolone, 0.5 mg/kg/d). OUTCOMES The right abducens nerve palsy improved and the pituitary lesion shrank after the initiation of corticosteroid treatment. CONCLUSION Based on the diagnosis of IgG4-related disease in the retroperitoneal organ and response to corticosteroid treatment, this patient was diagnosed with IgG4-related hypophysitis. This hypophysitis caused enlargement of the pituitary gland with resulting nerve compression, causing abducens nerve palsy. When IgG4-related hypophysitis is suspected, a thorough examination of other organ lesions and biopsy should be considered.