The affected skin is gently scraped with a blade ... papules and pustules on the upper trunk, neck, and upper arms (see Figure 4). Malassezia yeasts grow in the follicles and produce inflammation.

In these cases, the acne is caused by clogged pores or follicles, but by a buildup of malassezia yeast. It’s the same yeast responsible for fungal acne. While scalp acne might just seem like an ...