Endocrine Abstracts

Introduction: Pituitary tuberculosis (TB) is a rare form of intracranial TB and remains a diagnostic challenge in the absence of systemic TB. A limited number of cases has been reported in the literature.

Case: A 47-year-old south Asian man presented to the accident and emergency department with complete isolated left third nerve palsy which had developed gradually over the course of a week. Brain magnetic resonance imagining (MRI) revealed a 15 mm inflammatory sellar and suprasellar pituitary mass extending cranially to the optic chiasm and laterally to the cavernous sinuses. Endocrine investigations showed secondary hypothyroidism, secondary adrenal insufficiency and secondary hypogonadism and hormone replacement therapy was commenced. The patient underwent a pituitary biopsy and the histological analysis revealed non-caseating granulomas and multinucleated giant cells. Pituitary and CSF tests for acid-fast bacilli (AFB) including AFB stain and PCR were negative. Further immunohistochemical work up showed positivity for Langerin and suggested V600E BRAF mutation with leading to a likely differential diagnosis of Langerhans cell histiocytosis (LCH) or Erdheim Chester disease. An increased glucocorticoid dose resulted in limited radiological improvement of the pituitary inflammatory changes. Whole body Positron emission tomography (PET) to assess for possible systemic disease involvement showed increased metabolic activity in the left hemithyroid and FNA was suggestive of a malignancy. A diagnostic left hemithyroidecomty revealed a follicular carcinoma. Repeat PET prior to starting steroid-sparing immunosuppression showed increased uptake in a left level IV lymphnode and subsequent biopsies revealed necrotising granulomatous lymphadenitis suspicious for TB. Initial TB PCR was negative, but culture from a repeat lymph node aspirate confirmed fully sensitive TB. Antitubercular treatment was commenced and resulted in full clinical recovery.

Conclusion: Pituitary tuberculosis is rare and difficult to diagnose. Therefore, a high index of clinical suspicion is required. Accurate diagnosis is essential to start prompt, curative antimicrobial treatment.