Cytolytic degeneration of keratinocytes adjacent to Langerhans cells in pityriasis rosea (Gibert).

Unique cytolytic degeneration of keratinocytes adjacent to Langerhans cells was observed in five cases of pityriasis rosea (Gilbert). In the cytolytic area, the normal keratinocyte structures were absent except for free ribosomes. In addition, a similar cytolytic part of a keratinocyte was enveloped by the elongated dendrites of the Langerhans cell and was detected within its cytoplasm. The significance of these findings is discussed with respect to anticytoplasmic antibodies in the sera of patients with pityriasis rosea.