Guttate psoriasis presents with pink papules with a silvery scale, which are more inflammatory and scaly than the reddish-brown, mica-scaled papules of PLC.
The papules of lichen planus are characteristically violaceous, polygonal, and flat-topped, a different morphology than the reddish-brown papules of PLC.
This is distinguished by a history of a new medication and resolution upon its withdrawal.
LyP consists of recurrent crops of larger papules that often ulcerate and heal with scarring, a more dramatic course than the persistent, non-scarring papules of PLC.
Pityriasis rosea is distinguished by its initial "herald patch" and the arrangement of its oval plaques in a "Christmas tree" pattern on the back.
The rash of secondary syphilis can be papulosquamous but often involves the palms and soles, and is confirmed by serologic testing.
The lesions of SPP are very thin, oval, slightly scaly patches ("digitate dermatosis"), not the discrete papules of PLC.
