Table 2. Proposed diagnostic criteria for pityriasis rosea.¹¹⁶.

A patient is diagnosed as having pityriasis rosea if:
on at least one occasion or clinical encounter, he/she has all the essential clinical features and at least one of the optional clinical features; on all occasions or clinical encounters related to the rash, he/she does not have any of the exclusion clinical features.
The essential clinical features are:
discrete circular or oval lesions; scaling on most lesions; peripheral collarette scaling with central clearance on at least two lesions.
The optional clinical features are:
truncal and proximal limb distribution, with less than 10% of lesions distal to mid-upper-arm and mid-thigh; orientation of most lesions along skin cleavage lines: a herald patch (not necessarily the largest) appearing at least two days before eruption of other lesions, from history of the patient or from clinical observation.
The exclusion clinical features are:
multiple small vesicles at the centre of two or more lesions; two or more lesions on palmar or plantar skin surfaces; clinical or serological evidence of secondary syphilis.