Pustulosis palmoplantaris. How initial ultrastructural alterations change into vesicles and pustules

The diagnosis pustulosis palmoplantaris describes a clinical aspect. Apart from the pustules, a different number of dyshidrotic vesicles characterize the clinical morphology. This study was carried out to elucidate a facultative relationship between vesicles and pustules. The first ultrastructural changes are small intercellular gaps in the basal layers of the epidermis containing one Langerhans' cell. Larger intraepidermal vesicles are filled with stimulated lymphocytes and interdigitating Langerhans' cells. Below the vesicle a dense infiltrate consisting predominantly of CD 8-positive cells was observed. Mature pustules are situated just beneath the stratum corneum and filled with a lot of granulocytes and only few lymphocytes. The subepidermal infiltrate is almost missing. Between vesicles and neighbouring pustules we could prove a direct connection below the stratum corneum, a direct subcorneal granulocyte pathway. The result is a vesicle with lymphocytes at the bottom and granulocytes at the top of its cavity--a transformed vesicle. The described intercellular cavities are considered as common evolutionary stages in the development of pustules and vesicles.