Langerhans cells in the dermal infiltrate of hyperkeratosis lenticularis perstans.

Typical papules obtained from a patient with hyperkeratosis lenticularis perstans (HLP) were examined by light and electron microscopy. Dense cellular infiltrate, which consisted mainly of mononuclear cells, was observed in the dermis underlying the lesion. Electron microscopic studies revealed that these cells were mostly lymphocytic cells. In addition, several Langerhans cells were found in the infiltrate, some of which were apposed to the lymphocytic cells. These findings suggested that immunologic reactions via Langerhans cells might occur in HLP and further raises a possibility that Langerhans cells might be involved in the pathogenesis of HLP.