Endocrine Abstracts

Hypopituitarism due to neurosarcoidosis is mainly seen in patients with extensive systemic disease. However, pituitary involvement can occur without other classical features of the disease, as illustrated by the following cases.

Case 1: An Afro-Caribbean male presented in 1986 with failure of pubertal development aged 22. Initial investigations demonstrated hypothalamic hypogonadism, secondary hypothyroidism and a suboptimal cortisol response to hypoglycaemia (peak 442 nanomoles per litre) CT of the pituitary was normal, and no explanation for his hypopituitarism was found.

Appropriate replacement treatment was started and he remained well until he presented with iritis in 1994. A chest X-ray revealed bilateral hilar lymphadenopathy and sarcoidosis was then confirmed by transbronchial biopsy. He was referred to our clinic for re-assessment, and MRI showed classical appearances of neurosarcoidosis with enhancement of the pituitary stalk following contrast administration.

Case 2: A 39 year-old Afro-Caribbean woman presented with a three month history of secondary amenorrhoea, fatigue and polyuria. Initial investigation revealed hypogonadotrophic hypogonadism, secondary hypothyroidism and diabetes insipidus and she was started on appropriate replacement treatment.

MRI revealed abnormal enhancement at the base of the pituitary stalk consistent with an inflammatory or infiltrative process. Extensive investigations failed to demonstrate any evidence of systemic disease or other inflammatory pathology. Her chest X-ray was normal but high resolution CT of the thorax revealed features suggestive of pulmonary sarcoidosis. This diagnosis was further supported by a gallium scan showing significant uptake in both lung fields, and a reduction in carbon monoxide transfer. Although these findings were clinically silent at presentation, she has subsequently developed progressive pulmonary sarcoidosis.

These cases demonstrate the importance of considering sarcoidosis in the differential diagnosis of hypopituitarism, even in the absence of obvious systemic features. In each case, hypopituitarism was the index event heralding the later development of severe systemic disease.