Endocrine Abstracts

A 53 year old woman developed a firm thyroid mass which was removed. The histology of the thyroid mass showed auto-immune thyroiditis and Langerhans cell Histiocytosis ( LCH). She also complained of thirst and polyuria. A water deprivation test confirmed cranial diabetes inspidus (CDI) ,the symptoms of which resolved on DDAVP . A glucagon stimulation test showed a blunted growth hormone (GH) response of 13.3 milliU per litre with an IGF-1 level of 16 nanomol per litre. The cortisol response was normal ( peak 1002 nanomol per litre). She had sub clinical hypothyroidism ( TSH 10.7 milliU per litre, free T4 15 picomol per litre) and positive thyroid microsomal antibodies ( 133 international units per litre: normal 0-73). Thyroxine 50 micrograms daily was commenced. An MRI scan showed no obvious hypothalamic-pituitary abnormality.

Over the next two years she developed fatigue and weight gain and repeat glucagon testing showed severe GH deficiency ( peak GH 9.0 milliU per litre; IGF-1 17 nanomol per litre) with a normal cortisol response. A repeat MRI scan was normal.

LCH is a proliferative histiocytic syndrome characterised by proliferation of Langerhans cells. Following antigen stimulation, Langerhans cells secrete cytokines. An exaggerated cytokine response with cellular infiltration and subsequent fibrosis leads to the clinico - pathological features of LCH. Endocrine involvement in the form of cranial DI and panhypopituitarism occurs due to involvement of the hypothalamic/ pituitary region.

Reports of isolated thyroid involvement in LCH are rare. It usually occurs in the presence of autoimmune thyroid disease suggesting it is a reactive process (as in our patient). Usually DI and hypopituitarism have been diagnosed before involvement of other organs by LCH becomes evident . However this was not the case in this patient.

Five years post partial thyroidectomy, she remains free of any other organ involvement by LCH.