ESPE Abstracts

Introduction: Central Diabetes Insipidus (CDI) is characterized by polyuria, polydipsia and weight loss, resulting from impaired secretion of Antidiuretic Hormone (ADH) in response to serum osmolarity changes. Langerhans Cell Histiocytosis (LCH)is an inflammatory myeloid neoplasm that can affect all organ systems, with central nervous system involvement frequently localized in the posterior pituitary. This report presents a case of pituitary stalk thickening detected in a patient presenting with CDI.

Case Presentation: A 12-year-3-month-old male patient presented with excessive thirst and frequent urination for one month. Physical examination revealed height:161 cm(+1.18 SD), weight:50 kg(+1.18 SD), body mass index:19.2 kg/m²(-0.05 SD), blood pressure:105/75mmHg, heart rate:89bpm, an 8x8 cm papular lesion on upper right thigh, Tanner stage 3 for puberty. The patient's kidney function tests, glucose profile, electrolytes, thyroid function tests, and cortisol levels are all within the normal range. To clarify the diagnosis of diabetes insipidus in the patient, a water deprivation test was performed. At the 2nd hour of the test, with a serum osmolality of 304.4 mOsm/kg and a urine osmolality of 57 mOsm/kg, the patient was diagnosed with diabetes insipidus. Following the administration of 60 mg Desmopressin, the urine osmolality, which was 235 mOsm/kg before the test, increased to 525 mOsm/kg (a 120% increase), leading to a diagnosis of CDI. Desmopressin treatment was then initiated for the patient. Pituitary MRI showed no T1 hyperintense focus in the neurohypophysis and the infundibulum was thickened(3.8mm). Serum Alpha-fetoprotein (AFP) and beta-HCG levels were within normal ranges. Clinical, laboratory, radiological findings suggested early LCH and systemic involvement was evaluated. No hematological involvement was found on peripheral smear and no lung, bone, liver or lymph node involvements were detected on imaging. No skin involvement was identified on punch biopsy and no activity uptake was observed on F-18 FDG PET-CT. Due to the invasiveness of transsphenoidal biopsy, initial follow-up with MRI was planned. Persistence of MRI findings led to a diagnosis of isolated central nervous system LCH. The patient received cranial radiotherapy(10Gy over 5 sessions)who is being monitored by multidiciplinary departments.

Conclusion: In cases of CDI with pituitary stalk thickening, differential diagnosis should include germinoma, LCH and lymphocytic hypophysitis. Due to the difficulty in obtaining a histological diagnosis in these cases, it’s important for radiological imaging to be evaluated by an experienced radiologist. Our patient was assessed by multidisciplinary council and deemed suitable to receive 5 doses of cranial radiotherapy.

Keywords: Central Diabetes Insipidus, Langerhans Cell Histiocytosis, Pituitary Stalk Thickening