Pityriasis Rosea on Chest, Neck, and Back of a 35-Year-Old Man

Disturbed by a pruritic rash of 5 days' duration on his chest, neck, and back, a 35-year-old man sought medical advice. The patient had no other symptoms.

Dr Sunita Puri of Decatur, Ala, diagnosed pityriasis rosea.

This mild, benign, self-limited disorder of unknown cause primarily affects young adults. The eruption occurs on the trunk.

Erythematous, oval lesions with slightly raised borders, or collarettes, vary in size from 0.5 to 2 cm. The long axis of the lesions follows skin cleavage lines, forming a “Christmas tree” pattern. Typically, a large, solitary mother, or herald, patch erupts on the trunk 5 to 10 days before the outbreak of crops of smaller lesions.

Generally, the rash resolves in 2 to 3 weeks. (In this patient, it resolved completely within 10 days.)

Antihistamines and prednisone may be used to treat the pruritus. Sunlight and ultraviolet light hasten involution of the lesions.