Abstract

Sarcoidosis is a multisystemic inflammatory disorder of unknown etiology, characterized by the formation of non-caseating granulomas in various organs. While pulmonary involvement is most common, extrapulmonary manifestations can present significant diagnostic and therapeutic challenges. Neurosarcoidosis, particularly involving the hypothalamic-pituitary axis, is a rare but serious complication that can lead to endocrine dysfunction, including hyponatremia. The association between chronic inflammatory states like sarcoidosis and the development of monoclonal gammopathies is also recognized but remains an area of ongoing research.

We present the case of a 68-year-old female with a history of hypertension and type 2 diabetes mellitus who was admitted with severe prostration and uncontrolled hyperglycemia. Her history was notable for recurrent episodes of severe hyponatremia, uveitis, and skin lesions resembling erythema nodosum. Initial investigations revealed euvolemic hyponatremia and panhypopituitarism, including central hypothyroidism and adrenal insufficiency. Imaging studies, including Magnetic Resonance Imaging (MRI) of the brain and a Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) scan, confirmed pituitary and myocardial involvement, leading to a diagnosis of multisystemic sarcoidosis. The patient responded dramatically to immunosuppressive therapy with steroids and levothyroxine replacement. However, six months later, she presented again with persistent weakness and anemia. Further evaluation revealed a monoclonal IgG lambda paraprotein on serum protein electrophoresis and immunofixation, with bone marrow examination showing dyspoiesis, consistent with Monoclonal Gammopathy of Undetermined Significance (MGUS).

This case highlights the complex interplay of endocrine, inflammatory, and hematological manifestations in a single patient with sarcoidosis. It underscores the importance of considering neurosarcoidosis in the differential diagnosis of recurrent euvolemic hyponatremia and pituitary dysfunction. Furthermore, it illustrates the potential for chronic inflammation in sarcoidosis to predispose patients to plasma cell dyscrasias like MGUS. Clinicians should maintain a high index of suspicion for these associated conditions to ensure timely diagnosis and appropriate management, including long-term surveillance for the potential progression of MGUS to multiple myeloma.