A 45-year-old man has recurrent fasting hypoglycaemia with inappropriately high serum insulin and negative contrast-enhanced CT of the pancreas. Biochemical testing confirms insulinoma. The single most useful next investigation for tumour localisation is:
- A Selective arterial calcium stimulation with hepatic venous sampling
- B Octreotide scan
- C Endoscopic ultrasound ✓
- D Intraoperative palpation alone without further imaging
Explanation
Endoscopic ultrasound detects more than 90% of insulinomas, including lesions under 1 cm that conventional CT misses, and allows fine needle aspiration if needed. Insulinomas express somatostatin receptors less densely than other neuroendocrine tumours, making octreotide scanning unreliable. Selective arterial calcium stimulation is reserved for cases where endoscopic ultrasound and CT both fail. While most insulinomas are ultimately found by careful intraoperative palpation combined with ultrasound, relying on palpation alone without attempted preoperative localisation is not standard practice.
Reference: Schwartz's Principles of Surgery, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.