Snapshot A 10-year-old boy is brought to his dermatologist for a developing rash. A couple of weeks ago, he recovered from a common cold. A week after, he developed an oval rash on his chest. Thinking it was a fungus infection, his parents applied anti-fungal cream to the area. However, a week after the first lesion appeared, he developed multiple smaller rashes in his lower abdomen. They are sometimes itchy, but only mildly so. Introduction Common, self-limited papulosquamous eruption Pathogenesis idiopathic often associated with URI seasonal pattern suggests viral etiology, though not confirmed potential link to herpesvirus types 6 and 7 Epidemiology children young adults Presentation Symptoms prodrome or URI within a month of onset little or no pruritus Physical exam herald patch, a single lesion usually on the trunk plaque with thin collarette of scale inside the border eruption in 1-2 weeks multiple smaller papules appear in “Christmas tree” distribution oriented along Langer (skin cleavage) lines rose-colored or violet resolution in 4-12 weeks resolves spontaneously without scarring Evaluation Diagnosis from clinical exam and history Diagnosis confirmed with skin biopsy potassium hydroxide preparation to exclude Tinea spp. Differential Diagnosis Tinea corporis Secondary syphilis (especially if palm and soles involved) Tinea versicolor Drug eruption Guttate psoriasis Treatment Observation lesions heal within 4-12 weeks Natural sunlight Prognosis, Prevention, and Complications Prognosis very good typically self-limited and self-resolving in 4-12 weeks Complications relapse