21 mo old has a small bump on back of head, close to bottom of hair line, under skin. feels like a swollen blood vessel, soft, but doesn't seem to bother her when we gently touch it. no discoloration. we just noticed it when my hand brushed over it.

Likely lymph node: There are thousands of lymph node located around the body that help screen out germs in the body serum. There are many in the neck, head & behind the ear. At rest these are often 1/4 inch in diameter (pea sized) and may grow to marble sized when reacting to a stimulus. Bug bites, or viral infections can increase their size.What you describe is normal.If concerned review this with the kids doc.

Moniter: Likely cyst will not worry If it keeps enlarging in size ,needs to see physician