Overlap syndrome between sarcoidosis and Sjögren's disease presenting as hypopituitarism: case report and review of literature.

Sarcoidosis is a granulomatous disease that affects multiple organs; however, pituitary involvement is extremely rare. Although autoimmune diseases, such as Sjögren's disease (SjD), may coexist, overlapping cases presenting with hypopituitarism are exceedingly rare. A 76-year-old man was admitted with hyponatremia and altered consciousness as chief complaints. Endocrine testing revealed panhypopituitarism, and magnetic resonance imaging showed pituitary gland and pituitary stalk enlargement with homogeneous enhancement. Whole-body imaging revealed extensive lymphadenopathy. Histological examination of lymph node and lung biopsy specimens revealed non-necrotizing granulomas, indicative of sarcoidosis. Salivary gland biopsy and autoantibody testing confirmed the presence of concomitant SjD. Hormone replacement therapy markedly improved pituitary enlargement and pituitary hormone secretion, allowing the discontinuation of replacement therapy after 137 days. However, despite the improvement in pituitary and lymph node lesions, interstitial pneumonia subsequently developed due to SjD, necessitating systemic immunosuppressive therapy. In conclusion, this case demonstrates a rare overlap between sarcoidosis presenting with hypopituitarism and SjD, in which pituitary lesions improved, but immune activity progressed in other organs. Thus, immune-mediated disease activity may differ between organs in overlapping syndromes, and pituitary lesions in sarcoidosis do not necessarily parallel systemic disease activity.