Endocrine Abstracts

A 25-year-old Asian man presented with a 6 month history of erectile dysfunction, loss of libido and reduced exercise tolerance. His past medical history included ulcerative colitis, treated with long-term prednisolone and mesalazine for 8 years. He weighed 116 kg and his BP was 144/86 mmHg. He had bilateral gynaecomastia but no galactorrhea. Testicular volumes were 8 ml bilaterally and secondary sexual characteristics were normal. He was clinically euthyroid.

Endocrine investigations: Testosterone 0.3 nmol/l, SHBG 13 nmol/l, LH<0.5 IU/l, FSH<0.5 IU/l, IGF1 21.8 nmol/l, random cortisol 334 nmol/l, prolactin 817 mIU/l, FT₄ 13.3 pmol/l, TSH 1.79 mU/l.

While awaiting pituitary MRI, he was admitted to hospital with severe left sided headache, right hemiparesis and motor/sensory dysphasia. His MRI brain showed a soft tissue lesion encasing the right MCA with surrounding oedema and a similar lesion in the suprasellar region in close proximity to the pituitary stalk. The chest X-ray and subsequent CT chest showed diffuse mediastinal lymphadenopathy. Serum ACE was mildly elevated. Mediastinal node excision and biopsy showed extensive granulomatous lesions with central necrosis, in keeping with tuberculosis, despite absence of mycobacteria on ZN staining.

He was started on quadruple anti-tuberculous therapy, high dose prednisolone and testosterone replacement. His neurological deficit promptly resolved. Four months following diagnosis he was well with no symptoms of hypopituitarism. His short synacthen test showed a blunted response (baseline cortisol 86 mmol/l, 30 min post ACTH 334 mmol/l). This could arguably be due to either adrenal suppression secondary to long-term steroid use or ACTH deficiency due to hypothalamic/pituitary dissociation.

We present a case of central hypogonadism and partial hypopituitarism due to a pituitary stalk tuberculoma. Tuberculomas of the sellar and suprasellar region are rare and can cause variable degree of hypopituitarism. Given the rising incidence of tuberculosis, it is an important differential diagnosis to remember, especially in patients on immunosuppressive medications.