SUN-406 Complete Recovery of Central Diabetes Insipidus Associated with Isolated Stalk Thickening in a Neurosarcoidosis Patient

Background: Neurosarcoidosis (NS) affects ~15% of patients with sarcoidosis. Hypothalamic-pituitary (HP) involvement is even rare and occurs in <1% of sarcoidosis. Clinically, NS presents as neuroendocrine dysfunction in 2.5% and radiologically, it typically manifests as HP lesion with parenchymal disease. The literature review demonstrates increased pituitary volume as the most frequent MRI abnormality observed in more than a half patients with HP involvement. Pituitary stalk thickening (PST) has been reported in combination with parenchymal abnormality but not in isolation. Central diabetes insipidus (CDI) is a known manifestation of stalk involvement. The exact mechanism of anti-diuretic hormone (ADH) dysfunction is not well understood, however CDI is mostly attributed to defective ADH release with direct infiltration of the stalk. Hormonal deficiencies are considered to be irreversible even in the setting of normalization of MRI findings after treatment. We herein report a case of NS associated with isolated PST presenting as CDI, where complete recovery was observed. Case: A 54-year-old male with pulmonary and gastrointestional (GI) sarcoidosis confirmed by gastric biopsy, developed abrupt onset of polyuria-polydipsia [Intake: 11-12 L/d, Output: 8-10 L/d] while treated with prednisone 5 mg/d. Urine osmolality (osm) was 64 mosm/kg, urine sodium (Na) 10 meq/l, serum osm 292 mosm/kg and serum Na 143 mmol/l. MRI of the Sella revealed 3.5 mm PST, absent posterior pituitary bright spot and partial empty sella. Anterior pituitary evaluation showed: Testosterone 122ng/dl, FSH 9.8mIU/ml, LH 3.3mIU/ml, Prolactin 17.8ng/ml, TSH 1.07 mcIU/ml, FT4; 0.7ng/dl, Cortisol 11.3mcg/dl, ACTH 12pg/ml and IGF-1; 129ng/ml. DDAVP 0.2mg bid controlled DI well. GI symptoms were treated with increased prednisone 40 mg/d and hydroxychloroquine. MRI showed decreased PST at 2.6 mm in 1 year and normal stalk thickness 1.8 mm in 2 years. He was successfully weaned off DDAVP, along with a slow taper of steroid. Four years since presentation, symptoms are well controlled on prednisone 3mg/d. Testosterone improved (213 ng/dl) and other anterior pituitary hormones remained in normal range. He has no polyuria, stalk measures 1.9 mm and posterior pituitary bright spot is absent. Conclusion: This case demonstrates a rare manifestation of NS presenting with isolated PST associated with CDI, without parenchymal disease. Furthermore, this is the first case report of complete resolution of CDI that correlated with normalization of MRI finding. In general hormonal deficits with HP sarcoidosis is considered irreversible and no correlation has been reported between the hormonal dysfunction and radiologic outcomes. Hence, in similar patients with isolated PST as the only manifestation of NS a trial off DDAVP may be offered, if improvement in MRI finding is noted over the course of the treatment.