Can you guess the diagnosis of this teenaged girl with flat-topped papules?

Welcome to this Contemporary Pediatrics poll. Take a look at the case below. After reading through the description, choose a multiple-choice answer and try to guess the correct patient diagnosis.

Then visit our website on Wednesday at 12:00 PM ET for the full case presentation, differential diagnosis, and correct patient diagnosis.

This case was presented by Zeena Mestari and Bernard A. Cohen, MD.

The case

A 15-year-old girl presented with multiple, small, flat-topped, minimally scaly papules scattered over both forearms, some arranged in a linear pattern extending from the elbows to the wrists, that had been present for several months (Figure). She denied any associated pruritus, pain, color changes, or bleeding. Her medical history was unremarkable for immunodeficiency, atopic dermatitis, or other skin conditions. 

On examination, the patient appeared well nourished and in no distress. Vital signs were within normal limits. There were numerous 1- to 3-mm, flat-topped, minimally scaly, smooth, flesh-colored to lightly hyperpigmented papules distributed bilaterally over her forearms. The lesions were confined to the upper extremities, sparing the palmar surfaces of the hands. The remainder of the physical exam was unremarkable.