Endocrine Abstracts

Introduction: Central diabetes insipidus (CDI) is a heterogeneous condition characterized by the presence of polyuria and polydipsia due to a deficiency of arginine vasopressin. Frequently, CDI is wrongly considered idiopathic if not associated with other signs and symptoms.

Case report: We report the case of a 50-year-old woman diagnosed with idiopathic central diabetes insipidus at the age of 34. The MRI scan of the hypothalamus and pituitary gland was performed and did not show any abnormality. No further diagnostic procedures were performed at that time. The patient presented 14 years later with back pain. The physical examination revealed a suspicious thyroid nodule. A thoracic, abdominal and pelvic computed tomography scan showed osteolytic lesions in the thoracic and dorsal spine. Total thyroidectomy was performed and pathology revealed papillary carcinoma with lymph node metastases. She received 3.7 GBq (100 mCi) of iodine-131. The results of Post-ablation 131I whole-body scintigraphy were reported as negative with a serum thyroglobulin < 1 ng/mL. However the patient was still complaining of back pain.So we performed a second whole body bone scintigraphy which demonstrated increased uptake localised in the distal metaphysis of the femur and proximal of the shins, evoking in the first place a systemic origin. Dermatological examination revealed multiple papular lesions of 3 mm, non-itchy, discrete and confluent in some places. The lesions were coloured to yellow orange and red brown, affecting axillae and groins, appeared there 4 years ago. Anatomo - pathological examination of the cutaneous biopsy of these lesions concluded to a disseminated xanthoma.

Conclusion: Xanthoma disseminatum (XD) is an extremely rare and unique entity in the spectrum of non-Langerhans cell histiocytosis. XD may have central diabetes insipidus as their first manifestation. Involvement of the central nervous system occurs in approximately 40% of cases. The symptoms of diabetes insipidus may precede the dermatologic signs. This case highlighted the importance a long-term follow up of patients suffering from idiopathic CDI.