Endocrine Abstracts

Adult-onset Langerhans Cell Histiocytosis (LCH) is a rare disease characterised by the abnormal proliferation of Langerhans cells, and has a distinct phenotype to that of childhood-onset LCH. Diabetes Insipidus (DI) is a well-recognised manifestation of LCH, caused by infiltration of the hypothalamo-pituitary axis (HPA). Anterior pituitary dysfunction is an uncommon complication of LCH, which has been shown to be associated with DI. However, this association has previously only been studied in childhood-onset or mixed populations of adult and childhood-onset LCH patients.

This study retrospectively audited the extent of screening and the occurrence of anterior pituitary dysfunction in adult-onset LCH patients with DI under follow-up at the Hammersmith hospital. Importantly, patients who had received cranial radiotherapy were excluded.

20 out of 71 patients with adult-onset LCH had DI confirmed by water deprivation test. 12 out of 20 patients with DI had been screened for anterior pituitary dysfunction with baseline pituitary function tests. 6 of these 12 patients had evidence of deficiency of at least one anterior pituitary hormone. (1= low 9am cortisol (less than 100 nanomols per litre); 2= hypogonadism (low gonadal steroids or low gonadotrophins); 1= low free thyroxine with low thyroid stimulating hormone; 1= growth hormone deficiency; 1= low 9am cortisol with hypogonadism and growth hormone deficiency). Only 2 of the 6 patients with evidence of anterior pituitary dysfunction had undergone dynamic testing. Radiological abnormalities of the HPA were seen in 5 out of the 13 patients with imaging. Anterior pituitary dysfunction was detected in all but one of these 5 patients.

This study demonstrates a high prevalence of anterior pituitary dysfunction in adult-onset LCH patients with DI. However it also reveals that screening of anterior pituitary function in adult LCH patients with DI is not uniformly practised. We therefore recommend that all adult-onset LCH patients with DI have regular screening of anterior pituitary function and imaging of the HPA.