| Arthropod bites | Papules in a linear pattern; usually appearing in groups of three on exposed skin |
| Secondary syphilis | Red or copper-colored lesions on the trunk and extremities, including palms and soles, that may have thin scaling |
| Drug eruption | Patient history of prescription or over-the-counter medication use; often has a more diffuse distribution, including the chest and back |
| Eosinophilic folliculitis | Pruritic papules, typically on the upper body; can be associated with human immunodeficiency virus infection |
| Papular atopic dermatitis | Possible patient history of asthma, seasonal respiratory allergies (atopy), itching, or skin eruption in flexural areas |