A Lump on the Back of a 7-Day Old Infant's Head

Anything unusual in a new baby worries a parent. Those who notice a lump on their baby's head may be frightened that something is wrong with him, but they shouldn't worry. In most cases, that lump is not harmful and will fade as the baby grows older. In an extremely rare case, a lump on your baby's head may be a sign of a serious complication of delivery and will need treatment.

Possible Causes

There are several possible causes of a lump on the back of a newborn's head. Most are fairly common, heal on their own and will leave no lasting effect. These benign causes of a lump include soft spots, which are very common and will disappear as the baby grows. Less common, but still benign, causes of a lump on a newborn's head are a caput succedaneum and a cephalohematoma 23. These are both types of swelling, often caused by a rough delivery, and will also heal on their own. A very serious, but rare, cause of a lump on an infant's head is a leptomeningeal cyst, which can be diagnosed by a head X-ray and requires surgery 4.

Soft Spots

All babies have a soft spot, also called a fontanel, on the back of their head. Fontanels occur where the bones of the skull are separated and are completely normal. Fontanels are not a sign of any health issues in the baby. The fontanel on the back of the head will be triangular and feel soft to the touch. Gently touching the fontanel will not hurt the baby. The fontanel may bulge out when the baby cries. This is normal. The baby's skull bones will grow together, causing the fontanel on the back of the baby's head to disappear by the time she is 6 months of age.

Caput Succedaneum

Also known simply as caput, caput succedaneum is swelling of an infant's head, caused by the pressure of the vaginal walls during delivery 2. Difficult deliveries or deliveries that needed the aid of a vacuum have a higher chance of causing a caput. A physical examination will diagnose a caput, and no treatment is necessary. The swelling will subside, and there will be no long-term effects.


Cephalohematoma is caused by blood vessels under the scalp breaking during delivery and is more common in forceps or vacuum deliveries 3. Blood collects under the scalp and forms a swelling with distinct borders that feels squishy, like a small water balloon. This type of swelling requires no treatment. In fact, trying to drain the cephalohematoma may cause infection 3. The trapped blood will be broken down and absorbed into the baby's system. During the course of the absorption, calcium deposits replace the blood to form a hard mass. This hard mass is also nothing to worry about. It, too, will be absorbed into the baby's system. By the time the baby is a few months old, there will be no trace of the hard mass. Not even an X-ray will show signs of the cephalohematoma 3.

Even though a cephalohematoma is nothing to worry about, the symptoms can be confused with a rare and serious condition called a leptomeningeal cyst 34. A head X-ray will provide a correct diagnosis.

Leptomeningeal Cyst

A leptomeningeal cyst is an extremely rare complication of a skull fracture that may occur during delivery 4. There is a membrane, called the dula mater, between the brain and the skull. Occasionally, when the skull is fractured during a rough delivery, this membrane can become caught between the fractured edges of the skull. The sign of a leptomeningeal cyst is a soft, squishy lump on the baby's head, similar to the symptoms of a cephalohematoma 34. If the doctor believes that it is the more serious condition of a leptomeningeal cyst, he will order a skull X-ray, which will provide a correct diagnosis 4. If left untreated, a leptomeningeal cyst can result in seizures and mental retardation 4. Surgery is required to repair the dula mater.