Fine-needle aspiration biopsy of an islet cell tumour simulating pancreatic carcinoma

The importance of distinguishing between malignant islet cell tumour and pancreatic carcinoma is emphasized in this report of a 57-year-old woman who presented with an epigastric mass. Clinically and radiologically it was diagnosed as a pancreatic adenocarcinoma. A fine-needle aspiration biopsy specimen obtained under ultrasonic guidance showed tumour cells suggestive of an islet cell tumour. Immunostaining and electron microscopy were performed on the aspirate. The tumour cells stained positive with antibodies to keratin, glucagon and gastrin; ultrastructural examination revealed neurosecretory granules, confirming the diagnosis of an islet cell tumour. Angiography was performed to assess the possibility of debulking the mass. This case demonstrates the value of immunohistochemistry and electron microscopy on fine-needle aspiration biopsy specimens of the pancreas to differentiate islet cell tumours, which are potentially curable, from pancreatic adenocarcinomas, which carry a 5-year survival rate of less than 2%.