Pitfalls in diagnosing a small cystic insulinoma: a case report.

Insulinoma is a rare pancreatic endocrine tumour and is typically sporadic and solitary. Over 90% of all insulinomas are benign. Cystic insulinomas are also rare. It is not difficult to determine the site of such neoplasm, as cystic insulinomas are usually 4-10 cm in diameter. We present the case of a patient with a histologically confirmed cystic insulinoma diagnosed after approximately 10 years of hypoglycaemia symptoms. This case is unique because of the small size (2.2 cm) of the tumour. Endoscopic ultrasound (EUS) was useful for localizing this tumour.