APPENDIX - Carcinoid tumour

This is the distal half of an appendix. The tip is occupied by a discrete yellow-coloured tumour which does not extend through to serosa.
This patient presented with acute abdominal pain at the age of 18. An appendectomy was performed and the appendix showed evidence of inflammation (not shown in the specimen) as well as tumour. A carcinoid tumour in the appendix is nearly always benign. It is formed from the neuroendocrine (or argentaffin) cells in the mucosa. The term argentaffin refers to the ability of the cells to reduce silver salts when appropriately stained. The yellow colour in the lesion is due to lipid.