Pityriasis rosea: This common skin disease causes patches on the skin. Your dermatologist may call the large patch a mother patch. The smaller patches are daughter patches.
Pityriasis rosea (pit-uh-rahy-uh-sis row-zee-ah) is a common skin disease that causes a rash. This rash usually disappears on its own without treatment. You can expect to see the rash for about 6 to 8 weeks. Sometimes the rash lasts much longer.
This rash can be very itchy.
Some people who develop this rash see a dermatologist to get treatment for the itch.
If this rash appears during pregnancy, a woman should tell her doctor.
Learn more about pityriasis rosea:
Image used with permission of the American Academy of Dermatology National Library of Dermatologic Teaching Slides