Can your skin catch a cold? If you suddenly notice these spots, be suspicious.

The weather was nice, so Ms. Lee, an office worker in her 30s, started running outdoors. Soon after, a pink spot the size of a fingertip appeared on her stomach. She dismissed it as just a stretch mark and didn't take it seriously. Soon, two or three more red spots appeared, spreading to her sides and thighs. The affected area began to itch and peel, prompting Ms. Lee to see a dermatologist, who diagnosed her with "rosacea."

Pityriasis rosea is an acute inflammatory skin disease, nicknamed "the cold of the skin." It often occurs during seasonal changes when immunity is low, and cold symptoms like headache, malaise, and fever sometimes precede the rash.

The rash begins as pink, oval spots in the center of the torso, then spreads outward in a diagonal downward pattern, resembling a Christmas tree. These spots are usually surrounded by a thin, white, scaly layer of scale. While the rash occasionally spreads to the arms and legs, it rarely appears on the neck or face. Three out of four patients also experience itching. It most commonly occurs in patients aged 15 to 40, and is more common in women.

Although the exact cause is unknown, the most likely hypothesis is that herpes simplex virus types 6 and 7 become active when the immune system is weakened, causing rosacea. It is not contagious.

Most rashes disappear on their own after 6 to 8 weeks, and unless they cause significant discomfort, no specific treatment is necessary. However, if itching or excessive rash occurs, antihistamines and topical steroid creams can be used to alleviate symptoms. Phototherapy may also be used.

If the spots persist for several months after six to eight weeks, it's best to see a dermatologist for an accurate diagnosis. There are many skin conditions with similar symptoms that can be confused with them, including secondary syphilis, nummular eczema, seborrheic eczema, guttate psoriasis, tinea versicolor, and viral rashes.