GASTROINTESTINAL AUTONOMIC NERVE TUMORS - A REPORT OF 9 CASES

We describe the clinicopathological features of gastrointestinal auton omic nerve tumours in nine patients where the diagnosis was confirmed by electronmicroscopy. Most patients presented with abdominal pain, At laparotomy, large intra-abdominal tumour masses were found which tend ed to be cystic and haemorrhagic. The predominant histological pattern s were nests, sheets and fascicles of spindle and epithelioid cells, I mmunohistochemistry showed positive staining for neuron specific enola se (9/9), PGP 9.5 (9/9), NKI/C3 (7/9), vimentin (7/9), alpha-smooth mu scle actin (5/9), vasoactive intestinal peptide (3/9) and CD34/QBend10 (2/9), Grimelius staining was positive in two of nine cases. All tumo urs were negative for CAM 5.2, chromogranin, synaptophysin, Leu 7, neu rofilament protein, muscle-specific actin (HHF-35) and desmin (D33), U ltrastructural examination showed cellular processes and dense-core gr anules in all cases, Three tumours had microtubules and/or intermediat e filaments, particularly in cell processes, Skeinoid fibres were seen in three cases, No convincing synapses or small (synaptic-type) vesic les were identified. There was no evidence of epithelial, smooth muscl e or nerve sheath differentiation. Two patients died due to tumour, tw o died of unknown causes and the remainder are alive 2-44 months after presentation, Four of the five survivors have recurrent/residual intr a-abdominal tumour, So-called gastrointestinal autonomic nerve tumours are apparently slow-growing malignant tumours showing neuronal differ entiation. Four cases arose in the mesentery/retroperitoneum or omentu m rather than bowel wall and therefore a more appropriate nomenclature might be intra-abdominal stromal tumour with neuronal differentiation .