Congenital dermal sinus is an uncommon form of cranial or

spinal dysraphism Neural tube defects (NTDs) are a group of birth defects in which an opening in the spine or cranium remains from early in human development. In the third week of pregnancy called gastrulation, specialized cells on the dorsal side of the embry ...

. It occurs in 1 in 2500 live births. It occurs as a dermal indentation, found along the midline of the neuraxis and often presents alongside infection and neurological deficit. Congenital dermal sinus form due to a focal failure of dysjunction between the cutaneous ectoderm and

neuroectoderm Neuroectoderm (or neural ectoderm or neural tube epithelium) consists of cells derived from ectoderm. Formation of the neuroectoderm is first step in the development of the nervous system. The neuroectoderm receives bone morphogenetic protein-inhi ...

during the third to eight week of gestation. Typically observed in the lumbar and

lumbosacral The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordates ...

region, congenital dermal sinus can occur from the

nasion The nasion () is the most anterior point of the frontonasal suture that joins the nasal part of the frontal bone and the nasal bones. It marks the midpoint at the intersection of the frontonasal suture with the internasal suture joining the nasa ...

and

occiput The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

region down. Early diagnosis and treatment is crucial for cases of congenital dermal sinus. It ensures that neurological condition does not degrade and prevents infection. Diagnosis can be confirmed through the use of advanced

neuroimaging Neuroimaging is the use of quantitative (computational) techniques to study the structure and function of the central nervous system, developed as an objective way of scientifically studying the healthy human brain in a non-invasive manner. Incr ...

to observe the tract and associated

lesions A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classifi ...

Embryogenesis

During normal development, cutaneous ectoderm separates from

to allow for the insertion of mesoderm. That is, the skin separates from the tissue of the spinal cord to allow proper formation of the

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordate ...

. In cases of congenital dermal sinus there is a failure in this process, resulting in formation of a persistent connection between the skin and neural tissue. This manifests as a tract extending from the surface of the skin to the spinal cord lined with stratified squamous epithelium, surrounded by dermal and neurological tissue. The tract may terminate in the

deep fascia Deep fascia (or investing fascia) is a fascia, a layer of dense connective tissue that can surround individual muscles and groups of muscles to separate into fascial compartments. This fibrous connective tissue interpenetrates and surrounds the ...

, or even make contact with neural elements. Congenital dermal sinus may form at any point along the midline of the neuraxis, however, the majority form in the lumbar and lumbosacral region (41% and 35% of cases respectively).

Diagnosis

Congenital dermal sinus is often diagnosed in

infants An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...

and children. Early diagnosis is important in congenital dermal sinus, so that treatment can be provided early, to prevent progression of associated complications.

Clinical features

There three key hallmarks of congenital dermal sinus: cutaneous abnormalities,

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...

, and neurological deficits.

Cutaneous abnormalities

Congenital dermal sinus is a tract from the surface layer of the skin, through the deeper tissues into the cranial or spinal cavity. The skin findings of this tract can include: * Pit along neuraxis * Flat capillary

hemangioma A hemangioma or haemangioma is a usually benign vascular tumor derived from blood vessel cell types. The most common form, seen in infants, is an infantile hemangioma, known colloquially as a "strawberry mark", most commonly presenting on the ski ...

Hypertrichosis Hypertrichosis is an abnormal amount of hair growth over the body. The two distinct types of hypertrichosis are generalized hypertrichosis, which occurs over the entire body, and localized hypertrichosis, which is restricted to a certain area. ...

Skin tag A skin tag, or acrochordon (pl. acrochorda), is a small benign tumor that forms primarily in areas where the skin forms creases (or rubs together), such as the neck, armpit and groin. They may also occur on the face, usually on the eyelids. ...

* Abnormal pigmentation * Subcutaneous

lipoma A lipoma is a benign tumor made of fat tissue. They are generally soft to the touch, movable, and painless. They usually occur just under the skin, but occasionally may be deeper. Most are less than in size. Common locations include upper back, ...

* Signs of local

Infection

The stratified squamous epithelium of the congenital dermal sinus tract can extend to the spinal fascia of the

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

or all the way to the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...

. Thus, the congenital dermal sinus forms a point of entry for infection, this can allow for the formation of an abscess, especially among children. Infection can then travel up the spinal cord to result in meningitis, which can be fatal if left untreated.

Neurological deficit

Congenital dermal sinus is often also associated with

spinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the br ...

drainage, intradural

cysts A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

and

tethering; conveying neurological deficit. Neurological deficit can occur due to spinal cord compression from intradural

dermoid cyst A dermoid cyst is a teratoma of a cystic nature that contains an array of developmentally mature, solid tissues. It frequently consists of skin, hair follicles, and sweat glands, while other commonly found components include clumps of long hair ...

growth in the epidermis and dermis. Tethered spinal cord can result in gait difficulties and

sphincter A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. Sphincters are found in many animals. There are over 60 types in the h ...

dysfunction, as well as compressing the spine. Neurological deficits are more likely to occur where diagnosis has not been timely, allowing cysts and or infection.

Imaging

Magnetic Resonance Imaging (MRI) is the preferred tool for diagnostic and preoperative imaging of congenital dermal sinus. MRI allows the neural structures to be observed, visualizing the tract and its anomalies and lesions. For example, exposing tethered cord, inclusion tumors or spinal cord malformations. Observation by

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

is limited in diagnosis, especially due to immature

calcification Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature Ma ...

of infants less than 18 months. X-ray may be used in conjunction with MRI or sonogram images to assist preoperatively.

Treatment

Treatment of congenital dermal sinus involves complete resection of the tract as well as intradural exploration.

Prophylactic Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...

surgical removal of the congenital dermal sinus tract is beneficial for the patient, allowing neurological and bladder function to be maintained. Early surgical intervention results decreases the risk of infection and/or tumour progression – factors typically associated with delayed presentation of congenital dermal sinus. ] Intradural exploration is necessary as excision of the entire tract, as well as any of its intradural connections, reduces need for further surgical intervention. The surgical technique involves ‘removing the cutaneous lesion in ellipse’. The tract of the congenital dermal sinus must then be explored and excised, with intradural lesions dissected. If not all epithelial tissue is removed, there is a possibility for the dermoid cyst to reoccur and require further operation. Further operations are limited by postoperative and post-infection scarring.

History

Prior to pervasive use and availability of advanced methods of neuroimaging, it is possible that the rate of incidence of congenital dermal sinus has been supplemented by the incidence of coccygeal pits. Coccygeal pits are distinct from congenital dermal sinus as they are found within the

gluteal cleft The intergluteal cleft or just gluteal cleft, also known by a number of synonyms, including natal cleft, butt crack, and cluneal cleft, is the groove between the buttocks that runs from just below the sacrum to the perineum, so named because it f ...

, rather than above the gluteal cleft. The

caudally Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

orientated coccygeal pits are not associated with intradural pathology and do not need to be excised, unlike the cephalically oriented tracts of the congenital dermal sinus which confer great intradural pathology and require surgical intervention. While coccygeal pits occur in 4% of

neonate An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...

population, congenital dermal sinus is only found in 1 in 2500 live births.

References

{{Congenital malformations and deformations of musculoskeletal system Congenital disorders of nervous system Congenital disorders of musculoskeletal system Cutaneous congenital anomalies