Pityriasis Rosea

Question 1

Age of onset and M/F predominance?

Answer 1

female predominance, 10-35 y/o

Question 2

Times of year when PR most commonly occurs?

Answer 2

spring and fall

Question 3

Pathogenesis of PR:

Answer 3

• possibly viral (HHV 6 and HHV 7) - Drug induced: ACE inhibitors (most common), NSAIDS, gold, bismuth, B-blockers, barbs, isotretioin, metronidazole, clonidine

Question 4

Which drugs can cause drug induced PR?

Answer 4

ACE inhibitors (most common), NSAIDS, gold, bismuth, B-blockers, barbs, isotretioin, metronidazole, clonidine

Question 5

Describe clinical features of PR

Answer 5

• begins with “herald patch”= solitary pink, enlarging plaque w/ fine central scale and larger trailing collarette of scale favoring the trunk - diffuse eruption that begins hours to weeks later of oval patches/plaques on trunk and proximal extremities - lesions appear similar to herald patch, but smaller - lesions distributed in Christmas tree pattern, vertically oriented along Langers lines

Question 6

How long after Herald patch do you get other lesions?

Answer 6

• hours to weeks later

Question 7

What % of patients get pruritus with PR?

Answer 7

• 25%

Question 8

What are the types of atypical PR?

Answer 8

• inverse PR (intertrigenous, OR when limbs more affected than trunk) - Papular, vesicular, or targeted morphology (more common in African American children) - Oral involvement (e.g. Ulceration)

Question 9

Papular, vesicular or targetoid morphology PR is more common in which population?

Answer 9

• African american children

Question 10

Clinical difference between classic PR and drug induced?

Answer 10

• drug-induced PR-like eruptions have increased inflammation/pruritis, lack the herald patch, and occur in older population

Question 11

Histopathology of PR:

Answer 11

• Non-adherent thin mounds of parakeratosis (vs thicker mounds of guttate psoriasis) - spongiosis - perivascular lymphohistiocytic infiltrate, and RBC extravasation

Question 12

Treatment of PR:

Answer 12

• non required - can treat itch with topical CS or antipruritic lotions - oral erythromycin hastens clearance.

Question 13

prognosis/clinical course of classic PR:

Answer 13

• self-limited (6-8 weeks)

Question 14

prognosis/clinical course of drug induced PR:

Answer 14

• resolve rapidly (<2weeks) after discontinuing medication