Endocrine Abstracts

Introduction: Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytic multisystem disorder, which mainly presents with multifocal sclerotic lesions of the long bones, followed less frequently by heart, lung, central nervous system, skin, pituitary, and orbital involvement. Here, we presented a rare case of ECD manifested in a young male subject with pituitary involvement.

Clinical Case: A 19-year-old man was referred to our outpatient clinic with polydipsia and polyuria. He complained of headaches, retro-orbital pain, and swelling in the scalp. Physical examination showed bilateral exophthalmos, and bone swelling on the right frontal and parietal bone. In laboratory examination, urine density, serum sodium, and serum osmolarity were 1005 g/mL, 140 mEq/l, and 285 mOsm/kg; respectively. His FSH, LH, free testosterone, growth hormone, and IGF-1 levels were low, and the remaining anterior pituitary hormones were within normal range. The water deprivation test confirmed the diagnosis of Arginine vasopressin deficiency (AVP-D) and desmopressin nasal spray (10 µg/day) was started. Pituitary magnetic resonance imaging showed 8x6 mm nodular enlargement with diffuse contrast enhancement after intravenous contrast material (IVCM) injection in the middle part of the distal-pituitary gland. Multiple mass developments, enlargement of the diploe distance both in the fronto-occipital and parietal bones were observed after IVCM. A 4×2.5×2.5 cm lesion extending to the cerebellar vermis was observed in the posterior fossa. Radiographic investigation of the long bones determined lytic lesions and positron emission tomography revealed an increased uptake of 18F-FDG in the both proximal humerus, radius, ulna, distal ends of femur, tibiae and all bones in the cranium. Resection of posterior fossa lesion was performed and pathology revealed foamy CD68+, CD163+, S100-, CD1a– histiocytes, sparse giant cells, and fibrosis. This diagnosis of ECD was confirmed both histologically and immunohistochemically. BRAF V600E mutation screening was positive. Vemurafenib 480 mg twice daily was started due to the central nervous system involvement. Bone pain was regressed three months after the treatment, and anterior pituitary hormone deficiency was recovered. However, AVP-D persisted.

Conclusion: Diabetes insipidus is usually the first and most common endocrine manifestation of ECD. Hypopituitarism is rare but in order from most frequent to least; hypogonotrophic hypogonadism, growth hormone deficiency, thyrotropin deficiency, and adrenocorticotropic hormone deficiency can be present. Treatment is warranted for patients with symptoms or those with evidence of central nervous system involvement or organ dysfunction. Pre-existing AVP-D and endocrinopathies typically tend to persist, even after radiographic regression of disease.