Blueberry muffin baby is the characteristic distributed purpura occurring as a result of extramedullary hematopoiesis found in infants. The purpura are often generalized, but occur more often on the trunk, head, and neck. The name is from the superficial similarity to a blueberry muffin.
Blueberry muffin baby Wikipedia
The condition was originally considered characteristic of rubella, but is now considered to be potentially associated with many other conditions, such as cytomegalovirus and metastatic neuroblastoma.