Immunohistochemical demonstration of substance P-containing nerve fibres in glomus tumours.

Substance P (SP), S-100 protein, methionine-enkephalin, serotonin and myelin basic protein were studied in two solitary glomus tumours of the skin by peroxidase-antiperoxidase immunohistochemistry. Multiple SP-containing nerve fibres were distributed in the parenchyma of the tumour among proliferating glomus cells, and in the oedematous stroma of the tumour. Positive staining for myelin basic protein was detected in nerve fascicles in the capsule of the tumour, but not within the glomus tumour. S-100 protein immunoreactivity was found in nerve fascicles in the capsule of the tumour, and in addition, a few cells positive for S-100 protein were scattered throughout the stroma of the tumour. No positive staining for methionine-enkephalin and serotonin was found. The present finding may explain the clinical experience that the tumour is tender and can cause severe paroxysmal pain, because SP is known to be a primary sensory afferent neurotransmitter for mediating nociception. A possible role of SP for vasodilation in the glomus tumour is also discussed.