Somatostatin immunoreactive cells and Merkel cells in psoriasis.

Sir, We have reported previously on the increase in the number of somatostatin-immunoreactive cells with dendritic morphology in psoriatic skin (1, 2). The number of Merkel cells is increased in the psoriatic epidermis and, in contrast to the situation in normal skin, a subgroup of Merkel cells expresses somatostatin (3). This prompted the question as to whether the somatostatin-positive cells in our previous reports are Merkel cells (2, 4). Neuron-speci®c enolase (NSE) has been reported in several studies to be a reliable marker for Merkel cells in human epidermis (5, 6). The aim of the present study was to investigate whether there is a co-localization of somatostatin and NSE among the dendritic cells in psoriatic skin, which could indicate that the somatostatin-positive cells are in fact Merkel cells.