Abstract
Developmental anomalies are congenital disorders that represent either malformations due to faulty embryologic development or disruptions caused by damage to normally developing structures. Midline skin lesions on the nose and scalp often represent developmental anomalies with the potential for intracranial extension, including dermoid cysts as well as neural tube defects such as cephaloceles and heterotopic brain or meningeal tissue. Likewise, cutaneous lesions overlying the spine can serve as a marker for spinal dysraphism. Aplasia cutis congenita reflects abnormal or disrupted intrauterine skin development and can be approached clinically based on the morphology and distribution of the lesions and the types of associated findings. Other developmental anomalies include congenital lips pits, branchial cleft sinuses, cutaneous dimples, abnormal dermatoglyphs, the amniotic band sequence, and accessory tragi, nipples and digits. Some are isolated defects while others are associated with additional cutaneous or visceral manifestations. The most common and significant developmental anomalies, their evaluation, and therapeutic interventions are reviewed.
Keywords
cephalocele, heterotopic brain tissue, meningocele, dermoid cyst, spinal dysraphism, aplasia cutis congenita, lip pit, accessory tragus, supernumerary nipple, rudimentary polydactyly, dermatoglyphs, amniotic band sequence
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The human neural tube is thought to close in an intermittent, multisite pattern, and neural tube defects that present as midline cutaneous lesions (e.g. cephaloceles, heterotopic brain tissue, rudimentary meningoceles) typically occur at the junction between two closure sites
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Midline lesions of the nose and scalp have a high likelihood of representing developmental defects with a potential intracranial connection, and an evaluation with CT or MRI prior to surgical intervention is critical
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The presence of a “hair collar” surrounding a lesion on the scalp is a sign of ectopic neural tissue or membranous aplasia cutis; the latter is thought to represent a forme fruste of a neural tube defect
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Cutaneous lesions overlying the spinal axis can serve as a marker for spinal dysraphism, and their presence is often an indication for radiologic evaluation
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Aplasia cutis congenita, a physical finding reflecting a disruption of intrauterine skin development, can be approached clinically based on the morphology and distribution of lesions as well as the presence or absence of associated abnormalities
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A number of other developmental anomalies affect the skin; although they usually represent isolated defects, it is important to be aware of potential associated conditions
Introduction
Developmental anomalies are a diverse group of congenital disorders that result from faulty morphogenesis. They include both malformations , defined as structural defects arising due to errors in embryologic development, and disruptions , which occur when a structure programmed to develop normally is damaged before it is fully formed. A classic example of the former is incomplete closure of the neural tube resulting in an encephalocele, while the latter process is illustrated by the anomalies associated with varicella embryopathy. Although developmental anomalies that affect the skin are often recognized at birth or during infancy, occasionally diagnosis is delayed until later in life. The cutaneous abnormalities range in severity from isolated, minor physical findings (e.g. rudimentary supernumerary digits) to deforming, potentially life-threatening defects (e.g. deep, irregular scalp aplasia cutis congenita in Adams–Oliver syndrome). Furthermore, some skin lesions that themselves appear to be innocuous may serve as important clues to the presence of a multiple congenital anomaly syndrome or, particularly when involving the midline, the existence of a serious defect of the underlying tissues. Such associations reflect the complex interactions between various ectodermal and mesodermal elements that occur during the intricate processes of morphogenesis and differentiation.
This chapter begins with an overview of the midline lesion and its relationship to closure of the neural tube. A discussion of specific issues pertaining to midline lesions of the nose, scalp and spine follows, including a review of the different types of anomalies that can present in these sites. An overview of aplasia cutis congenita is followed by presentation of a clinical approach based on the morphology and distribution of lesions and the presence or absence of associated abnormalities. Finally, a variety of non-midline developmental anomalies are discussed, including lip pits, accessory tragi, supernumerary nipples, skin dimples, malformations of the dermatoglyphs, rudimentary supernumerary digits, and the amniotic band sequence. Developmental anomalies that are covered in Chapter 110 include ear pits as well as branchial cleft, thyroglossal duct, bronchogenic, median raphe, omphalomesenteric duct, and urachal cysts.
The Midline Lesion
A number of critical events occur during the third to fifth weeks of embryologic development (see Ch. 2 ). These include formation of the neural tube, separation of neuroectoderm from surface ectoderm, and interposition of mesodermal elements. Inherent in such a complicated process is the potential for error, which spans a spectrum from obvious, fulminant neural tube defects to subtle cutaneous anomalies. However, the latter may represent a sign of a significant underlying malformation.
Classically, closure of the human neural tube was thought to be a continuous process, beginning at a single focus in the cervical region and progressing bidirectionally in a “zipper-like” fashion to culminate in the closure of the anterior and subsequently posterior neuropores. However, evidence suggests that in humans as well as other mammals, the cranial segment of the neural tube closes in an intermittent or multisite pattern. Four distinct initiation sites of neural tube closure have been identified in the mouse, and a similar pattern of closure has been proposed for humans, with an additional caudal site ( Fig. 64.1 ) . In support of the multisite closure model, neural tube defects (e.g. cephaloceles, myelomeningoceles, heterotopic brain/meningeal tissue) cluster either entirely within one closure site or at the junction of two sites, such as the nasal root (2–3) or vertex (2–4; see Fig. 64.1 ). Neural tube closure in the posterior cranial area is thought to occur via a membrane rather than a midline fusion of folds, and the appearance of this site during embryologic development in animals resembles that of human membranous aplasia cutis . Specific genes may control individual closure sites, explaining repetitive events within families.
Midline Lesions of the Head and Neck
The pathogenesis, differential diagnosis and management of midline lesions of the nose ( Fig. 64.2 ) and scalp are discussed below, followed by a review of the individual developmental anomalies that may present with a midline lesion on the head or neck. Midline cysts of this region (e.g. thyroglossal duct, bronchogenic) are discussed in Chapter 110 .
Midline nasal lesions
It is important for physicians to recognize the potential intracranial connection of a midline nasal mass or pit . Dermoid cysts, dermal sinuses, cephaloceles, and heterotopic brain tissue (nasal gliomas) resulting from faulty embryologic development of the frontobasal skull and/or adjacent ectodermal/neuroectodermal tissues all may present as congenital nasal lesions ( Table 64.1 ). As a group, these midline nasal masses occur in ~2–5 per 100 000 live births. They are often misdiagnosed as more familiar entities such as epidermoid cysts and infantile hemangiomas.
| THE DIFFERENTIAL DIAGNOSIS OF NASAL MASSES PRESENTING AT BIRTH OR DURING INFANCY |
| Developmental defects |
| Other cysts |
|
| Benign neoplasms and hamartomas |
|
| Malignant neoplasms |
|
† The most common cause of a congenital midline nasal mass.
The various congenital midline nasal masses have similar developmental origins. As the bones of the skull form during the second month of gestation, diverticula of dura mater project: (1) inferiorly into the prenasal space that extends from the base of the skull to the nasal tip, deep to the nasal bone and skin but superficial to the nasal cartilage; and (2) anteriorly through the nasofrontal fontanelle into the glabellar area. These diverticula may make connections with the overlying dermis, but usually they regress completely, with subsequent bony fusion to form the base of the skull and the cribriform plate. However, if the dura mater does not separate from the dermis, an ectodermal residue, with or without a patent intracranial connection, can persist; furthermore, if faulty neural tube closure results in a bony defect, there may be herniation of brain tissue. Such ectopic elements can occur either within the prenasal space (nasoethmoidal, “intranasal”) or superiorly at the glabella (nasofrontal, “extranasal”) . Depending on the contents of the lesion (e.g. cutaneous versus neural tissue, cyst versus tract only) and the patency of the intracranial connection, a dermoid cyst, dermal sinus, cephalocele, or nasal glioma results (see below).
Many of these midline nasal lesions have the potential for intracranial communication, and, consequently, present a risk for the development of serious CNS infections such as meningoencephalitis or a brain abscess. In addition, recurrent inflammation and progressive expansion of the mass may result in bony atrophy and nasal distortion. Early and complete surgical excision with repair of associated bony and dural defects is imperative. In order to prevent ascending infections, a biopsy, needle aspiration, or other preoperative manipulations should be avoided.
A thorough radiologic evaluation prior to surgery is mandatory. Ultrasound may detect some bony defects but has limited sensitivity. While CT is the most sensitive method for defining bony skull defects, false-positive studies are common in young children undergoing bone maturation. MRI is superior in demonstrating intracranial masses and other soft tissue changes and may aid in planning surgical approaches . In addition, surgical exploration is often necessary to definitively exclude the presence of an intracranial connection, as small fibrous tracts may not be detectable with imaging studies.
Midline lesions of the scalp
Subcutaneous nodules of the scalp are common, and in adults they are usually acquired lesions, such as epidermoid and tricholemmal cysts. However, midline scalp lesions that are noted at birth or in early childhood have a high likelihood of representing developmental defects, such as dermoid cysts, cephaloceles, heterotopic brain or meningeal tissue, and aplasia cutis congenita. In one series of 70 children presenting with a solitary, non-traumatic scalp nodule , 61% of the lesions were dermoid cysts and 4% cephaloceles. More importantly, 37% of the lesions were found to extend intracranially to the dura or brain.
In the evaluation of a patient with a subcutaneous nodule on the scalp, clinical clues that heighten suspicion of a developmental anomaly with potential intracranial extension include :
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a patient who is an infant or child
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a lesion first noted at birth or during early childhood
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a family history of neural tube defects
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a history of meningitis
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the presence of neurologic signs or symptoms
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location of the lesion along the midline or over the suture lines of the scalp
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lesions that pulsate, transilluminate, or fluctuate in size with crying or straining
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lesions with a central pore in young children, who are less likely to have epidermoid cysts
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an overlying capillary malformation (port-wine stain)
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a positive hair collar sign (see below).
The hair collar sign consists of a ring of long, dark, coarse hair surrounding a congenital scalp nodule. The presence of a hair collar is a relatively specific marker for ectopic neural tissue . Hair collars are also seen in membranous aplasia cutis ( Figs 64.3 & 64.4 ), a disorder thought to represent a forme fruste of a neural tube defect (i.e. without the presence of ectopic neural tissue) . Drolet et al. hypothesized that cerebral herniation produces aberrant shearing forces during the formation of hair follicles early in development, causing them to point outward from the defect. The proximity of neuroectoderm expressing neural adhesion molecules may also alter normal epidermal–dermal interactions, thereby inducing the development of large, abnormal follicles . These speculations correlate with the histologic and dermoscopic finding of numerous horizontally oriented, hypertrophic follicles emerging from the edge of scalp lesions to form the hair collar . The differential diagnosis and evaluation of a positive hair collar sign is presented in Fig. 64.5 .
Other developmental anomalies of the scalp
Sinus pericranii is a rare disorder characterized by a congenital, or occasionally acquired, epicranial venous malformation of the scalp that communicates with an intracranial dural sinus through dilated diploic cranial veins . The lesion is usually located near the midline, especially in the frontal region. Most are asymptomatic and appear as a compressible, fluctuant mass that varies in size with changes in intracranial pressure ( Fig. 64.6 ). The differential diagnosis includes a simple venous or arteriovenous malformation, meningocele or encephalocele.
Hairless congenital scalp lesions such as a nevus sebaceus (see Chs 62 & 111 ) and nevus psiloliparus (a hallmark of encephalocraniocutaneous lipomatosis; see Ch. 62 ) due to mosaic activating mutations may mimic developmental anomalies of the scalp.
Dermoid cysts
Dermoid cysts result from sequestration of ectodermal tissue along embryonic fusion planes during development. They are a separate entity from benign cystic teratomas, neoplasms that are also referred to as dermoids. Although dermoid cysts are congenital defects and may be recognized at birth, these lesions often escape notice until they become enlarged, inflamed, or infected. This typically occurs by early childhood, but diagnosis may be delayed until as late as the sixth decade of life. Dermoid cysts present as firm, non-compressible, non-pulsatile subcutaneous nodules that often reach a size of 1–4 cm in diameter. The lesions usually do not transilluminate. They are most commonly located around the eyes, particularly the lateral eyebrow ( Fig. 64.7 ), but may also be found on the nose, scalp (often over the anterior fontanelle or the midline occiput), neck, sternum, sacrum, and scrotum.
Dermoid cysts on the nose or midline scalp have a much higher likelihood of intracranial extension than those in a periocular location. Nasal lesions, which account for <10% of cervicofacial dermoid cysts, occur anywhere from the glabella to the tip of the nose (see above) and can result in a widened nasal bridge. The presence of a sinus ostium, which may be heralded by protruding hairs or a sebaceous discharge, increases the risk of intracranial involvement of a nasal dermoid cyst to almost 50%, versus ~25% overall . A sinus ostium without an underlying subcutaneous mass may also connect with an intracranial dermoid cyst. These lesions favor the midline occipital area but can occur elsewhere on the face and scalp; recurrent drainage and inflammation may represent signs of deeper extension . In addition to infectious complications, a chemical meningitis or even hydrocephalus due to release of keratinous and sebaceous material into the cerebrospinal fluid (CSF) can occur with intracranial dermoid cysts. Lastly, dermoid cysts and dermal sinuses overlying the spine may be associated with occult dysraphism (see below) and if the tract connects with the subarachnoid space, an increased risk of meningitis.
Histologically, dermoid cysts in any location are lined by keratinizing stratified squamous epithelium and contain mature adnexal structures (see Ch. 110 ) . Treatment is by excision, and preoperative imaging studies are required for lesions located on the nose, midline scalp, or posterior axis or those with other suspicious features (e.g. a draining sinus ostium) in order to exclude a connection to the CNS.
Cephaloceles
Cephalocele is a general term for congenital herniation of intracranial structures through a defect in the skull. Cranial meningoceles are herniations in which the sac contains meninges and CSF, while encephaloceles contain both meninges and brain ( Fig. 64.8 ). Therefore, by definition, all cephaloceles have an intracranial connection. These lesions result from faulty closure of the cephalic portion of the neural tube during development, and they are much less common than their caudal counterparts (e.g. myelomeningoceles). Cephaloceles occur in ~1–3 per 10 000 live births, with a higher incidence in those with a family history of neural tube defects and an ~5% risk of neural tube defects in subsequent siblings. They are usually midline or paramedian, occurring most frequently at the occiput or vertex (75%) (see Fig. 64.1 ), followed by extranasal (e.g. glabella or medial orbit; 15%) and intranasal or pharyngeal (10%) locations . Encephaloceles are generally noted early in life due to the resultant deformity. Occasionally, small frontal lesions are misdiagnosed as deep infantile hemangiomas, vascular malformations, hypertelorism, or nasal polyps ; of note, the latter are almost never seen in children younger than 3 years of age.
Cephaloceles typically appear as a soft, compressible, pulsatile mass with a bluish color. They may be covered with either normal skin or a thin, glistening epithelial membrane. The size of cephaloceles varies tremendously, from 1 cm nodules to lesions containing nearly half of the brain, and the size does not necessarily correlate with the extent of the underlying bony defect. Patients with intranasal cephaloceles often present with a broadened nasal bridge but no palpable mass, whereas lesions on the scalp may have an overlying capillary malformation and/or a surrounding hair collar (see above, Midline lesions of the scalp) . Transillumination frequently indicates the presence of CSF; in addition, increased flow of CSF into lesions with crying, the Valsalva maneuver, or compression of the jugular veins (Furstenberg test) may result in transient expansion. Leaks of CSF can occur (e.g. CSF rhinorrhea), and patients may have a history of meningitis. Nasal cephaloceles may develop in conjunction with facial clefts and other midline defects, while encephaloceles are often associated with neurologic abnormalities.
On histologic examination, encephaloceles show mature neuroglial tissue embedded in varying amounts of fibrous stroma. Heterotopic brain tissue (see Fig. 64.8 ) demonstrates similar features, and these lesions cannot be reliably distinguished histologically. When a patient is suspected of having a cephalocele, imaging studies and subsequent neurosurgical repair should be performed.
Nasal gliomas
▪ Nasal cerebral heterotopia ▪ Nasal heterotopic brain tissue
An extranasal glioma typically presents as a firm, non-compressible, non-pulsatile, non-transilluminating mass at or just lateral to the nasal root ( Fig. 64.9 ; see Fig. 115.20 ). The overlying skin is often red with prominent telangiectasias, which may result in misdiagnosis as an infantile hemangioma; however, nasal gliomas do not undergo the proliferative and involutional phases that characterize the latter lesions. Intranasal gliomas may manifest as a widened nasal bridge or a polypoid nodule within the nasal cavity, sometimes protruding from a nostril. They occasionally cause nasal obstruction resulting in respiratory distress, and lesions involving the nasopharynx may be associated with a cleft palate . Excessive lacrimation or strabismus may occur ipsilateral to nasal gliomas .
Histologically, nasal gliomas demonstrate well-circumscribed nodules composed mostly of astrocytes, admixed with other glial cells and loosely textured intercellular glial substance interwoven with fibrous tissue. Neurons may or may not be present focally, and there are often prominent dilated blood vessels in the lesion and overlying skin. Immunoperoxidase staining for S100 protein and glial fibrillary acidic protein (GFAP) is positive. After imaging studies to determine whether an intracranial extension is present, nasal gliomas should be surgically excised.
Heterotopic brain tissue and rudimentary meningoceles
▪ Rudimentary meningoceles – heterotopic meningeal tissue, sequestrated meningoceles, meningeal hamartomas
Heterotopic brain tissue and rudimentary meningoceles typically present as a 1–4 cm solid or cystic subcutaneous nodule, often with a blue–red hue. Occasionally, rudimentary meningoceles have a bullous appearance and are clinically indistinguishable from membranous aplasia cutis . Lesions are often located in the midline occipital or parietal scalp, where they can manifest with alopecia of the overlying skin and/or a surrounding hair collar. An overlying capillary malformation also may be present.
Histologic features of heterotopic brain tissue are as described for nasal glioma. Although classic findings such as cystic cavities lined by meningothelial cells are present in some cases of rudimentary meningocele, the histologic features are often subtle, with meningeal elements simulating the appearance of vascular or loose connective tissue. While signs such as the tendency of meningocytes to encircle collagen bundles and the presence of psammoma bodies may be helpful, immunohistochemical staining for epithelial membrane antigen (EMA) and vimentin are critical in establishing the diagnosis . Because the presence or absence of an intracranial connection cannot be reliably determined by clinical examination, imaging studies should be performed prior to surgical excision.
Midline cervical clefts
A midline cervical cleft is a rare congenital anomaly resulting from incomplete fusion of the branchial arches in the ventral midline of the neck. Approximately 100 cases have been reported to date in the English-language literature, with a female-to-male ratio of 2 : 1 . Midline cervical clefts may be isolated or found in association with other defects, including other midline clefts (e.g. lower lip, tongue, mandible) and thyroglossal, branchial cleft, or bronchogenic cysts.
Patients present at birth with a vertically oriented, linear cleft on the midline neck at any point between the inferior edge of the mandible and the sternum. The lesion is covered with atrophic skin, which is often weeping in the neonatal period. Additional features may include a blind mucosal sinus tract inferiorly and a skin protuberance superiorly. A subcutaneous fibrous cord deep to the latter may extend upward to the chin, resulting in progressive cervical contracture and/or webbing of the neck with extension (pterygium colli medianum).
Histologically, midline cervical clefts consist of parakeratotic stratified squamous epithelium without normal adnexal structures. The subcutis often contains dense connective tissue, and fibrous cords may include bundles of skeletal muscle. Following ultrasonography to evaluate for an associated thyroglossal duct cyst (see Ch. 110 ), complete surgical excision and closure via Z-plasty should be performed as early as possible. Vertical primary closure is avoided to reduce the risk of cicatricial contracture.
Sternal clefts and supraumbilical raphae
Sternal clefts are rare congenital malformations that result from defective embryologic fusion of paired mesodermal bands in the ventral midline. These lesions most frequently involve the superior sternum, but inferior clefts and a complete bifid sternum can also occur. The skin overlying sternal clefts may be atrophic ( Fig. 64.10 ), scarred or ulcerated, and a dermal sinus tract is occasionally present. Approximately 40% of sternal clefts are associated with PHACE(S) syndrome ( p osterior fossa malformations; h emangiomas; a rterial, c ardiac and e ye anomalies; s ternal cleft/ s upraumbilical raphe; see Ch. 103 ) . The sternal abnormality in PHACE(S) syndrome may be limited to cutaneous atrophy or a pit in the presternal area, with intact underlying bone . For sternal clefts associated with a substantial bony defect, surgical repair can be performed to protect the mediastinal organs and improve respiration as well as cosmesis. A supraumbilical raphe is a rare midline abdominal defect that presents as a firm, scar-like, linear protuberance extending cephalad from the umbilicus. Supraumbilical raphae often occur in association with sternal clefts, sometimes simultaneously as manifestations of PHACE(S) syndrome.
Midline Lesions of the Spine
Spinal dysraphism refers to abnormal fusion of dorsal midline structures during embryologic development . This term encompasses a wide variety of congenital spinal defects, ranging from myelomeningoceles (protrusion of the spinal cord and meninges with no overlying skin) and other overt anomalies in which neural tissue is exposed ( open spinal dysraphism ) to less obvious, skin-covered malformations ( closed or “occult” spinal dysraphism ). The latter include diastematomyelia (a split in the spinal cord), meningoceles, intraspinal lipomas, lipomyelomeningoceles (protrusion of the cord extraspinally into an attached lipoma), tight or fatty filum terminale, dermoid cysts, dermal sinuses, and isolated posterior spina bifida .
The degree of neurologic impairment associated with closed spinal dysraphism is variable. Any lesion that produces traction and/or pressure can cause progressive damage to the spinal cord, resulting in neurologic symptoms. Whereas isolated posterior spina bifida, an incidental radiographic finding in 15–25% of the general population, is not clinically significant, other forms of dysraphism may become symptomatic by childhood or adolescence. Some patients, however, do not present until adulthood. When diagnosis is delayed, many of the aforementioned malformations can result in the tethered cord syndrome, which occurs when the conus medullaris (normally at the adult position of L1–L2 by 3 months of age) is low-lying and/or immobile. This syndrome is characterized clinically by back pain, urinary incontinence, motor and sensory deficits of the lower extremities, and orthopedic deformities ( Fig. 64.11 ). Occasionally, an acute onset of symptoms is precipitated by childbirth, heavy lifting, or spinal trauma. Early diagnosis allows timely neurosurgical intervention that can halt progression and prevent potentially irreversible neurologic damage.
Because the skin and the nervous system share an ectodermal origin, concurrent anomalies of these tissues are common. Midline cutaneous lesions thus serve as a valuable marker for spinal dysraphism, and in the majority of patients, they are the finding that leads to the diagnosis. Approximately 80% of individuals with closed spinal dysraphism have paraspinal skin abnormalities, and the majority of them have more than one type of skin lesion . In contrast, <3% of all neonates have cutaneous findings overlying the spine . Shallow coccygeal dimples and deep gluteal clefts occur in an additional 4% of infants; however, in contrast to dimples located superior to the gluteal cleft ( Fig. 64.12 ), these are considered as normal variants rather than a sign of an underlying malformation . Most of the cutaneous lesions associated with spinal dysraphism are located in the lumbosacral area, reflecting the relative rarity of neural tube defects in the cervicothoracic region .
Hypertrichosis is the cutaneous marker of spinal dysraphism most often evident at birth. Affected individuals may be born with a V-shaped lumbosacral patch of long, coarse or silky hair on the dorsal midline ( Fig. 64.13 ) known as a “faun tail” . Overall, however, lumbosacral lipomas are the skin lesions most commonly associated with spinal dysraphism . An intraspinal lipoma or lipomyelomeningocele often represents a portion of a larger subcutaneous lipoma, typically presenting as a soft mass located above the gluteal cleft and extending asymmetrically into one buttock. A curved gluteal cleft is suggestive of such a lesion, but clinical findings may be subtle initially, becoming more noticeable with time.
Infantile hemangiomas and vascular malformations located on or near the dorsal midline may also be signs of dysraphism. In addition to usually spanning the midline in the lumbosacral area, infantile hemangiomas associated with spinal dysraphism tend to have a segmental pattern and a superficial component, sometimes with minimal growth beyond reticular erythema and telangiectasias ( Fig. 64.14 ; see Ch. 103 ) . A patient with an isolated midline lumbosacral hemangioma >2.5 cm in diameter has an ~35% risk of having spinal dysraphism, which is higher if the hemangioma is larger, ulcerated or associated with additional cutaneous markers . Several acronyms have been proposed for the constellation of regional extracutaneous anomalies that can occur in individuals with segmental hemangiomas of the lower body; the most inclusive is LUMBAR syndrome : L , l ower body/ l umbosacral hemangioma and l ipomas or other cutaneous anomalies (e.g. “skin tags”); U , u rogenital anomalies and u lceration; M , m yelopathy (spinal dysraphism); B , b ony deformities; A , a norectal and a rterial anomalies; R , r enal anomalies. Of note, a telangiectatic patch overlying a spinal defect may actually represent an infantile hemangioma with minimal or arrested growth.
Vascular malformations are most often an indicator of dysraphism when they occur together with other midline cutaneous lesions, most notably lipomas. In Cobb syndrome, a spinal arteriovenous malformation is associated with cutaneous involvement in the same segment; such findings could occur as a manifestation of the capillary malformation-arteriovenous malformation syndrome due to RASA1 mutations. The cutaneous component may mimic a capillary malformation or angiokeratomas, and neurologic manifestations of cord compression can develop (see Ch. 104 ). Lastly, the common occipital capillary stain (“stork bite”), a form of nevus simplex, is not a marker for a spinal defect. Lumbosacral capillary stains often have rhomboidal or triangular shapes (“butterfly-like”) and are frequently associated with additional nevus simplex lesions of the head, neck, and (occasionally) upper back. Many authors feel that regardless of spinal level, capillary stains alone are rarely a sign of dysraphism . A prospective study of 3623 neonates found that 1 of the 25 individuals noted to have a sacral capillary stain in the absence of other lumbosacral skin lesions had a spinal abnormality revealed by imaging studies .
Cutaneous lesions of the spinal axis that should alert the clinician to the possibility of dysraphism are summarized in Table 64.2 . In one study , 39% (22/56) of neonates with “high-risk” stigmata such as hypertrichosis, subcutaneous masses, infantile hemangiomas, tails, or dimples above the gluteal cleft were found to have spinal dysraphism (see Figs 64.13 & 64.14 ). The presence of two or more skin lesions is a particularly strong sign; in another series, 61% (11/18) of such patients had spinal dysraphism, compared to 8% (3/36) of those with only one skin lesion .
| SKIN LESIONS OF THE SPINAL AXIS ASSOCIATED WITH DYSRAPHISM | |
|---|---|
| Lesion | Features |
| Lipomas | Soft subcutaneous mass, asymmetric buttocks, curved gluteal cleft ( Fig. 64.14 ) |
| Hypertrichosis | A V-shaped patch of long, coarse or silky hair (“faun tail”) ( Fig. 64.13 ) |
| Dimples | Above the gluteal cleft or >2.5 cm from the anal verge in neonates ( Figs 64.12 & 64.14 ); >0.5 cm in size or depth * |
| Dermal sinuses | Hair may be present at the ostium * |
| Acrochordons | May be associated with a dimple or dermal sinus |
| Pseudotails | Caudal protrusion due to prolonged vertebrae or hamartomatous elements, e.g. adipose tissue or cartilage ( Fig. 64.14 ) |
| True tails | Persistent vestigial appendage with a central core of mature adipose tissue, muscle, blood vessels and nerves |
| May be capable of spontaneous or reflex motion | |
| Infantile hemangiomas | Superficial, usually segmental pattern ( Fig. 64.14 ), often ulcerated |
| Telangiectasias | May represent an early, minimal/arrested growth, or regressed infantile hemangioma |
| Vascular malformations | Capillary malformations (CMs) are typically found together with other skin lesions |
| Cobb syndrome: spinal arteriovenous malformation associated with skin involvement in the same segment mimicking a CM or angiokeratomas | |
| Aplasia cutis congenita (ACC) | Ulcer, scar, or atrophic skin |
| Connective tissue nevus | Typically found together with other skin lesions |
| Hypo/depigmentation | May represent a nevus depigmentosus (typically found together with other skin lesions) or the residua of ACC |
| Hyperpigmentation | Typically found together with other skin lesions |
| Congenital melanocytic nevi | Spinal dysraphism has been reported in patients with neurocutaneous melanosis |
| Subcutaneous masses | May represent lipomas, meningoceles, lipomyelomeningoceles, teratomas, ependymomas, or plexiform neurofibromas |
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