Probable mechanisms of loss of Merkel cells in completely depigmented skin of stable vitiligo.

Vitiligo is frequently associated with segmental involvement. It spares paralyzed limbs in transverse myelitis. There is spontaneous repigmentation of vitiligo lesional skin (VL) in diabetic neuropathy. Increased neuropeptide in VL and adjacent normal skin of vitiligo (ANS) along with thickened nerve fibers showing ultrastructural abnormalities all indicate a neural pathogenesis (1). Loss of Merkel cells has been observed in early vitiligo lesional skin (2). Recently, catecholamines have been found to play a major role in initiating the cascade of events leading to loss of melanocytes (1, 3, 4). To investigate the presence of Merkel cells in the completely depigmented skin of stable vitiligo (SV), a study was undertaken using TROMA 1, a monoclonal antibody specific for adult Merkel cells. No TROMA 1-positive cells were observed in SV, whereas normal numbers of these cells were seen in ANS. This new finding further supports the hypothesis of neural involvement in vitiligo.