Clinical Features:

• Autosomal dominant familial and sporadic forms
• Large scaly plaques with islands of sparing, most often on the trunk
• Hyperkeratosis of the palms and soles and nail dystrophy may occur.

Histologic Features:

• Hyperkeratosis with horizontally and vertically alternating foci of parakeratosis (described as a "checkerboard" pattern)
• Mounds of parakeratosis at the edges of follicular ostia ("shoulder parakeratosis")
• Keratotic plugging of the follicular ostia
• Irregular to psoriasiform acanthosis with hypergranulosis and occasionally acantholysis
• Mild superficial perivascular lymphocytic infiltrate

Cases associated with this book:

Pityriasis rubra pilaris
Author: Artur Zembowicz M.D. Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection