Pityriasis Rosea
Pronunciation: pit-ih-RY-ah-sis ROH-zee-ah
A self-limiting, papulosquamous skin eruption characterised by a single herald patch followed by a generalised secondary eruption distributed along skin tension lines.
Full Definition
Pityriasis rosea is a common, benign inflammatory skin condition, most likely triggered by reactivation of human herpesvirus (HHV) 6 or 7, that begins with a solitary 'herald patch' (or 'mother patch')—a 2–5 cm oval, scaly plaque—followed days to weeks later by multiple smaller, fawn-colored oval lesions distributed in a 'Christmas tree' pattern along Langer's lines on the trunk. The condition typically resolves spontaneously within 6–12 weeks. Editors must note the correct spelling of 'pityriasis' (a frequent error is 'pityrasis') and should not confuse this with pityriasis versicolor or pityriasis lichenoides, which are distinct entities.
Usage
Usage note: 'Pityriasis' is frequently misspelled as 'pityrasis' or 'pityriasis'—verify spelling in all documents. Do not abbreviate to PR, as this may be confused with 'pulse rate' in clinical notes.
In Context
- "The GP's letter described a herald patch and secondary eruption consistent with pityriasis rosea." — GP referral letter
- "The patient information leaflet on pityriasis rosea was checked for the common misspelling 'pityrasis'." — Patient education material review