Endocrine Abstracts

Introduction: Langerhans cell histiocytosis (LCH) is a rare disease with incidence of 1–2 adults per milion/year. Pituitary function is affected in 30% of cases presenting almost always with diabetes insipidus. Other deficiencies such as GH, FSH+LH, TSH and ACTH follow. Erdheim–Chester disease is a rare Non-LCH described in several hundreds of cases in the world so far, with the pituitary function involvement in similar frequency as in LCH.

Case 1: A 36-year-old man has been treated for diabetes insipidus, central hypogonadism and severe GH deficiency of unknown origin since 2006. In 2014 MRI showed a hypothalamic lesion with involvement of pituitary stalk and other small lesions around IV. ventricle. PET/CT revealed maxillary and mandible lesions with adjacent soft and lymphatic tissue involvement. A biopsy from recently discovered scalp lesions, previously described as [foliculitis capitis] in the scalp, proved LCH. Otitis externa was another manifestation of LCH.

Case 2: A 42-year-old man has been diagnosed with isolated diabetes insipidus. MRI showed an infiltration of hypothalamus and pituitary stalk. Biopsy from suspicious papule on the arm did not reveal LCH as CD1a and S100 stains were negative. Additional PET/CT scan showed a multifocal bone involvement. The clavicle biopsy was in agreement with the skin papule biopsy and diagnosed an Erdheim–Chester disease.

Conclusions: Histiocytosis should be considered in case of a diabetes insipidus with/without other pituitary deficiency and hypothalamic lesion. Other organs such as bones, skin, lungs, lymphatic tissue and others can also be involved and PET-CT scan can reveal it. A biopsy from the extrapituitary lesion can lead to the diagnosis.