Primary hypothyroidism and essential hypernatremia in a patient with histiocytosis X.

A 27 year old woman with histiocytosis X had an unusual initial presentation with features of primary hypothyroidism and a goitre. Diagnosis was made by lung and thyroid biopsies. Endocrine tests showed the presence of hypopituitarism and a discrete suprasellar mass, consistent with hypothalamic histiocytosis X, was demonstrated by computerised tomography. Radiotherapy and chemotherapy arrested the clinical progression of the disease.