Cavernous sinus haemangioma masquerading as a pituitary macroadenoma: how the unexpected lurks in neurosurgery

Cavernous sinus haemangiomas are neoplastic lesions notoriously difficult to diagnose and excise. We present a case of a lesion that was clinically, biochemically, and radiologically consistent to a giant pituitary macroadenoma and discuss the unexpected near intra-operative exsanguination which enabled a pathognomonic diagnosis of a much rarer lesion to be made. This highlights the sinister nature of such a lesion, and its potential impact on patient care if partially excised, and that despite our advances in neurosurgical diagnostics the unexpected is to be expected.