Endocrine Abstracts

Langerhan cell histiocytosis (LCH) is a rare; incidence 1.8/100 000. It affects bone, skin, and pituitary but can involve any organ. Diabetes insipidus (DI) is reported in 15–50% of patients, and anterior pituitary dysfunction in 5–20%. We describe a patient whose diagnosis was delayed because of the challenge in making a tissue diagnosis.

A 42-year-old female presented in 2010 with sudden onset deafness and vertigo then 1 year later developed DI. Brain MRI showed absence of posterior pituitary bright spot, thickened pituitary stalk but no other lesion. Anterior pituitary function was normal except for hypogonadotrophic hypogonadism. She was commenced on desmopressin, with a good response. No diagnosis was made and surgery was not indicated. Twelve months later, she was tired and unwell, central hypothyroidism, and GH deficiency was diagnosed and replaced. Her MRI remained unchanged. Screening for tuberculosis, sarcoid, germinoma, skeletal survey, and bone marrow were normal. Six months later she complained of left arm, leg weakness and was admitted with obstructive jaundice. An MRI demonstrated focal areas of abnormal signalling within multiple bones and vertebrae, a mass in the thyroid and obstruction of common bile duct. An iliac bone biopsy showed infiltration with a mixed population of histiocytes staining for CD1a, CD45 and S100, suggestive of LCH. ¹⁸F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) CT demonstrated areas of abnormal activity in most of skeleton and low grade activity in pituitary, thyroid, and pancreas. A diagnosis of multisystem LCH was made. The biliary stricture was stented, she was treated with Vinblastine but her disease progressed and she was commenced on cyclical chemotherapy with cytarabine.

This case illustrates the complexity of diagnosing LCH, especially with the necessity of histology for definitive diagnosis and highlights that when LCH is considered screening is probably required with FDG PET.