Cutaneous Markers of Spinal Dysraphism

Fig. 8.1

A 1-day-old infant diagnosed prenatally with open neural tube defect and ventriculomegaly. The lesion is located at the lumbosacral junction and a closer look depicts split placode (arrow heads) and covered by glistening layer of arachnoid. This appearance is typical for open neural tube defects or spina bifida aperta

Cutaneous Manifestations

For the open neural tube defects (Fig. 8.1), the lesion is readily visible whether it was covered by intact skin or not. The challenge for primary care providers occurs with the occult or hidden/closed neural tube defects. Cutaneous manifestations represent minor aberrations in the development of surface ectoderm due to abnormalities in the dorsal endomesenchymal tract [10–12]. We will include the various skin manifestation of occult tethered cord below for easy identification.

Tuft of hair (or localized hypertrichosis) sometimes referred to as a “faun tail” [13] (Fig. 8.2).

Fig. 8.2

Localized hypertrichosis or hair tuft in the lumbosacral area. Typical appearance and considered highly suggestive of underlying spinal dysraphism, especially split cord malformations
Skin dimples [14, 15] (Fig. 8.3)

Fig. 8.3

Typical/simple skin dimple seen by spreading the glutei and notably close to the anal verge (a). An atypical skin dimple seen higher up in the back (b). This can be associated with an underlying dermal sinus track that leads to intradural lipoma as seen in MRI (c) (white arrowheads)

These can be classified into simple dimple/coccygeal pit, which are usually ≤5 mm in diameter and are 2.5 cm or less from the anus. They are localized just above the gluteal furrow and usually not associated with underlying dysraphism. Atypical dimples on the other hand are usually >5 mm in diameter and >2.5 cm from the anus (i.e., higher up in the back) and are highly associated with spinal dysraphism.

If you have to split the glutei to see the dimple, then this is low–lying and less suspicious for dysraphism. If it is readily visible on the back, above the upper gluteal limit, then the dimple is suspicious.
Asymmetric or malformed Gluteal cleft . These are referred to as duplicated or asymmetric or Y-shaped clefts or creases (Fig. 8.4).

Fig. 8.4

Asymmetric Y-shaped gluteal cleft that is moderately associated with spinal dysraphism except if present with other lesions
Subcutaneous lipomas

Usually occur in combination of other masses, e.g., hemangiomas /vascular malformations, hyrpertrichosis. There is a well-established association with intra-dural lipomas and spinal cord tethering so that the finding warrants further work up (Fig. 8.5).

Fig. 8.5

Subcutaneous lipoma with typical association with an asymmetric/deviated gluteal furrow. This association is considered highly suggestive of underlying spinal dysraphism
Hemangiomas and capillary vascular malformations

The use of nonuniform classification of the vascular skin lesions makes it difficult to draw conclusions about sensitivity and specificity of these midline lesions as markers of dysraphism. Incidence ranges from 2.6 to 12 % and are thought to represent angioblastic tissue that fails to unite formally with the developing vasculature of the body [16].

They usually occur in combination with other masses, e.g., subcutaneous lipoma or hypertrichosis. The isolated occurrence of vascular malformations designated as flat capillary hemangiomas is considered to have the lowest association with underlying intradural pathologies (Fig. 8.6) [17, 18]. Reports are evolving of retrospective [19] and prospective [14] studies showing a higher and significant association with occult spinal dysraphism when isolated flat capillary vascular malformation is found in a usual lumbosacral location.

Fig. 8.6

Typical appearance of a cutaneous hemangioma. This appearance along with other cutaneous vascular malformation is increasingly recognized as a marker for occult spinal dysraphism in some studies and reports
Tails or skin appendages

Tails are essentially vestigial remnants of the primitive coccyx that are supposed to undergo regression, while skin appendages may represent sometimes atretic meningoceles [20], a soft pedunculated skin tag or fibroma pendulum [21] (Fig. 8.7).

Fig. 8.7

Typical appearance of tail or vestigial appendage. This is considered also a highly suggestive cutaneous maker of an underlying spinal cord abnormality

The Predictive Value of the Skin Lesions

For clinicians, deciding when to order further imaging is predicated upon the simple question: What is the likelihood that this lesion represents a cutaneous manifestation of an underlying dystrophic state? While these lesions can never be perfectly predictive, Table 8.1 gives a guideline as to when various cutaneous manifestations should lead the pediatrician towards considering an imaging study under the correct clinical scenario. In a large prospective study of cutaneous markers of possible spinal dysraphism conducted in tertiary dermatology centers, atypical dimples were the most common skin manifestation of occult spinal dysraphism with a 55 % predictive value in accordance with previous reports [15]. Followed by lipomas and vascular anomalies are also demonstrating increasing correlation with spinal dysraphism [14]. Another retrospective study [1] found the port-wine stain (or flat capillary vascular malformation) and deviated gluteal furrow (DGF) to be the most commonly occurring skin markers either isolated or in combination, again followed by a subcutaneous lipoma . In sum, the results suggest that the occurrence of two or more lesions (especially with lipoma being one of them) was the strongest predictor of occult dysraphism, still in accordance with the earlier [22, 23] and later published literature [14]. Yet isolated vascular lesions in that study were not indicative of underlying spinal pathology.

Table 8.1

Risk of association of skin lesion

Only gold members can continue reading. Log In or Register to continue