Tumours may be innervated.

It is generally assumed that tumours are not innervated. However, following an accidental observation of a nerve fibre within an adenoma of the ciliary body epithelium of the eye, we have further examined two such tumours. One pigmented and one non-pigmented adenoma of the ciliary body epithelium (APCE and ANCE, respectively) that had been surgically removed from two human eyes were processed for ultrastructural evaluation and systematically screened and analysed for the occurrence of nerve tissue under a transmission electron microscope. The adenomas were composed of epithelial tumour cell strands and interposed vascularised connective tissue. Both tumours contained a small number of fine unmyelinated nerve fibres containing clear and dense core vesicles. In both adenomas, the nerve fibres were located in the tumour periphery close to blood vessels and tumour cells. In the APCE, they were also seen in more central areas. Since nerves always have a function, this finding, if confirmed in other neoplasms, may influence our understanding of such innervated tumours.