Ultrastructural diagnosis of neuroendocrine tumors using fine needle biopsy

Ultrasonic-guided fine-needle-biopsies of primary pancreatic tumours or liver metastasis were performed in 13 patients with neuroendocrine tumours of the gastrointestinal tract (5 carcinoids, 3 gastrinoma, 1 PPoma, 1 calcitoninoma, 1 insulinoma, and 2 non-functional tumours). Specimens obtained were examined on the light- and electronmicroscopic level. In all cases ultrastructural examination sufficiently revealed the correct diagnosis, due to the presence of cytoplasmic neuroendocrine granules within the tumour cells. Additionally performed immunocytochemical investigations at the ultrastructural level enabled the discrimination of gastrinomas, insulinomas, and PPomas. In contrast, light-microscopic examination was less sensitive for tumour classification. It is concluded that ultrastructural investigation of fine needle biopsies represents a valuable method to sufficiently discriminate neuroendocrine neoplasms.