Light and electron microscopic studies of pityriasis rosea.

Light and electron microscopic studies of biopsy specimens taken from five patients with pityriasis rosea revealed the most conspicuous finding to be the presence of dyskeratotic cells within the epidermis. Ultrastructurally, these cells contained an aggregation of tonofilaments, intracytoplasmic desmosomes, many vacuoles, and viral-like particles. It is assumed that pityriasis rosea is caused by a virus to which these changes are related.