ectopic/heterotopic brain tissue. Extracranial brain tissue without direct connection to the brain itself may be an isolated cutaneous embryonic defect that is usually located on the occipital or parietal area of the scalp. Most of the time these are harmless and can be removed. These often are called heterotopic brain tissue or cutaneous ectopic brain tissue or (CEB).
ECTOPIC OR HETEROTOPIC BRAIN TISSUE
Extracranial brain tissue that is directly connected to the brain itself may be an isolated cutaneious embryonic defect. These are usually located on the occipital or parietal areas of the scalp. They are often called heteropic brain tissue or cutaneous ectopic brain (CEB) (Janniger 1). Most of the time these are simple defective tissue that can easily be removed from the scalp. However, there are several different types of ectopic brain tissues and some of these can be signs of underlying central nervous system problems. Each of these cases shows the importance of getting a thorough evaluation of the tissue. Several different cases have been documented in the past and show the difference between benign cutaneous ectopic brain tissue and those that point to severe nervous system problems. The pediatrician should give a thorough evaluation of the brain tissue to determine if it is a serious problem.
Definition of Cutaneous Ectopic or Heterotopic Brain Tissue
Extracranial brain tissue without direct connection to brain itself may be an isolated cutaneous embryonic defect, usually on occipital or parietal areas of the scalp. It also is know as heterotopic brain tissue or cutaneous ectopic brain (CEB) (Janniger 1). There have been few actual studies concerning ectopic or heterotopic brain tissue, because these are rare. The cases that have been studied are similar. Lee and McLaurin described the first case in 1955 concerning a 1-year-old girl with an almost perfect circular, bluish-red plague that was almost 3 cm in diameter located on the posterior midline of the scalp. "Microscopically, heterotopic glial tissue in a pattern suggestive of abortive gyri and sulci was evident within the dermis" (Janniger 2). Since this case there have been several others described. It is frightening to the parent to find that her infant has an ectopic brain tissue on the head. It is important to reassure the parents so proper care can be given to the infant. The majorities of heterotopic brain tissue have no effect on the neurological development and are a rare development abnormality. However, there are cases that are similar and do present a serious problem for the infant. It is these cases that must be thoroughly evaluated to make sure there are no serious risks to the infant.
The heterotopic brain tissue may be an isolated embryonic rest or they can be a congenital herniation through the skull that eventually will lose connection. "Perhaps the neural tube initially outgrows, preventing closure of cranial or spinal coverings. Thus, its pathogenesis is uncertain" (Janniger 2). Any of these brain tissues should be thoroughly checked by neurologists. There have been some serious cases that lead to various serious problems in the child and can be fatal. Most of these are not "true" heterotopic brain tissue. There are many congenital cutaneous disorders of the scalps; most of these are quite uncommon. Heterotopic brain tissue or CEB are less common than encephalocele. "Encephaloceles usually are in the midline scalp, either hairless or with a collarette of hair. The nasal glioma, like CEB, may have no connection to underlying central nervous system structures. It appears on the nose as a smooth, often polypoid, tumor" Janniger 309). Most CEB cases do not tend to lead to serious deformities or anomalies. The prognosis for the infant is usually good without any serious underlying structures or any serious associated anomalies. The definition and explanation should be thoroughly to the parent so she does not get frightened and refuse treatment. This is a scary observation for the parent who needs assurance to give her infant the best medical care that can be provided. CEB usually does not lead to death and the prognosis is good in the majority of cases. It is important that these bald scalp plague or nodule by thoroughly evaluated by a neurosurgeon.
Summary of Four Patients with Scalp Nodules Surrounded by Hair Collars In the Study by Drolet and Clowry
The first patient observed had a 2.5 x 2.0 cm, fleshy, lobulated nodule with a central dimple. The MRI showed that posterior parietal encephalocele with bony defect and a Dandy Walker malformation. This was determined to be an encephalocele with an overlying port wine stain of 2 cm.
The second patient observed had a tense, translucent nodule 1.3 cm in diameter that was partially bisected by a fibrous band. This was determined to be a small parietal encephalocele with a dermal aggregation of neural tissue.
The third patient had a 2 x 1.8 cm translucent, blue cystic nodule. The infant was determined to have a heterotopic brain tissue with an overlying port wine stain.
The fourth infant had a 1.5 x 2.0 cm spongy, dermal nodule. The MRI showed subcutaneous mass with small intracranial communication. The fourth parent refused the surgery.
It could be that the parents of the fourth infant might have been frightened to allow their infant to go through surgery. This is not definitely true, but it is important to explain the situation to the parents and ensure them that most CEB's are not fatal and are often quite simple. Only in some cases are the CEBs fatal or are actually more than ectopic brain tissue that needs to be removed. The thorough evaluation of the pediatrician should reassure the parents about their infant.
History of CEB
Either the parents or physician will notice a cystic nodule at birth or shortly afterwards. "CEB usually is seen at birth as a 2-4 cm diameter, solitary, circular, bald scalp plague or cyst, which may be compressible" (Janniger 2). This plague or cyst may be skin colored or bluish and often tends to be located on the midline occipital or parietal scalp. There may be a collar of hypertrophic hair that surrounds the plague or cyst. There may be a cutaneous marker for neural tube closure defects on the scalp or sometimes this is called "hair collar" and consists of a ring of long, dark course hair that surrounds a midline scalp nodule. This should be a signal to the physician of an ectopic neural tissue that may be located in the scalp and that there may be serious underlying central nervous system malformations. A neurologist should always check these CEB. The cause for CEB is unknown. These ectopic brain tissues may begin during pregnancy or happen during the birthing. The heterotopic brain tissues may be an isolated ectopic neural tissue in the scalp or they can be underlying central nervous system malformations. These brain tissues need to be thoroughly evaluated and determine the best choice of treatment.
The neurologist may need to consider other problems, such as encephalocele, meningocele, cutaneous ectopic meningioma, neurofibroma, aplasia cutis congenital, hemangioma, lymphangioma, or melanotic progonoma. "The prominent collarette of hair that may have been seen in CEB also may be evident in a number of other neurocutaneous disorders (eg. Encephalocele, cutaneious meningioma)" (Janniger 3). There could be the possibility of dermal sinus or a direct connection to the central nervous system. The parents should seek a neurologist to evaluate any bald scalp nodule with diagnosis medical equipment, such as ultrasound or cranial tomograms. The neurosurgeon will decide on the best choice of treatment and explain this is to the parents before deciding what to do.
These procedures should be carefully and skillfully done because they can lead to retrograde infection should the lesion communicate with the brain. Sometimes these areas can become infected and need further treatment. Another serious problem of removing the CEB might happen if it overlaid "a large blood vessel such as the sagittal sinus, removal of what appears to be a crust of dried serum may produce a fatal hemorrhage" (Janniger 4). Most of the time CEB prognosis is good and leads to few complications. However, there are different cases that will be discussed that are serious complications. The medical team must not fail to be "alerted by the 'hair color' sign to the possibility of ectopic neural tissue in the scalp and/or underlying central nervous system malformations or fail to "perform complete evaluation, including possible ultrasound, cranial tomograms, and neurosurgical consultation, before cutaneous ectopic brain is excised" (Janniger 5).
There needs to be caution practiced in removing these ectopic brain tissues, because some of these may actually be attached to the brain and cause death. "Histological examination may show neural tissue staining with S-100 protein and glial fibrillary acid protein, but not with a neurofilament stain that suggests a glial cell origin" (Jannigar 309). Caution cannot be over stated due to the risks of some types of heterotopic brain tissues that are more serious.
The Hair Collar Sign: Marker for Cranial Dysraphism