Developmental anomalies are a diverse group of congenital disorders that result from faulty in utero morphogenesis. When they affect the skin, developmental anomalies can range in severity from isolated minor physical findings to potentially life-threatening conditions or cutaneous signs of significant extracutaneous defects.
Midline Lesions of the Nose or Scalp
• A midline mass or pit on the nose or scalp due to a dermoid cyst, cephalocele, nasal glioma, or other heterotopic brain/meningeal tissue (Fig. 53.1) may have a deeper component with intracranial extension.
• Hair collar sign: a peripheral ring of long, dark hair often surrounds ectopic neural tissue or membranous aplasia cutis congenita (ACC) on the scalp (Figs. 53.2 and 53.3); the latter is thought to represent a forme fruste of a neural tube defect.
Fig. 53.3 Spectrum of cranial neural tube defects.
• Rx: avoid biopsy or aspiration, which could lead to a CNS infection (e.g. meningitis); MRI or CT is required to assess extent prior to surgical intervention, which should include exploration to exclude intracranial extension and repair of any bony/dural defects.
• Most often located around the eyes, especially the lateral eyebrow region (Fig. 53.4); midline lesions on the nose, scalp, or back may have intracranial extension.
• Clues to the diagnosis include transillumination and transient expansion with crying or the Valsalva maneuver; nasal lesions may present with cerebrospinal fluid (CSF) rhinorrhea or a broad nasal bridge.
Nasal Gliomas, Other Heterotopic Brain Tissue, and Rudimentary Meningoceles
• A nasal glioma is a congenital mass of heterotopic brain tissue (HBT) at the nasal root/glabella > intranasally; the skin overlying this firm, noncompressible nodule tends to be red with prominent telangiectasias (mimicking an infantile hemangioma) (Fig. 53.5).
• Other HBT and rudimentary meningoceles typically present as a solid or cystic subcutaneous nodule on the midline scalp, often with a blue-red hue, overlying alopecia and a surrounding hair collar (see above); a rudimentary meningocele may have a bullous appearance and can also be located over the spine.
Midline Cervical, Sternal, and Supraumbilical Clefts
• A midline cervical cleft is a vertical band of atrophic skin on the mid anterior neck, often with a sinus tract inferiorly and a protuberance overlying a fibrous cord superiorly; surgical correction is needed to prevent neck contracture.
• A sternal cleft or supraumbilical raphe presents with a band of atrophic (Fig. 53.6), scarred or ulcerated skin; may occur in the setting of PHACE(S) syndrome (posterior fossa malformations; hemangiomas; arterial, cardiac, and eye anomalies; sternal cleft/supraumbilical raphe; see Chapter 85).
Fig. 53.6 Sternal cleft. Note the atrophic skin overlying the defect and prominent veins in the midline chest. Generalized desquamation is also evident in this 1-day-old post-term neonate. She did not develop an infantile hemangioma and had no cardiac defects or other features of PHACE(S) syndrome. Courtesy, Julie V. Schaffer, MD.
Midline Lesions Overlying the Spine
• Midline cutaneous lesions serve as a valuable marker for ‘occult’ spinal dysraphism and are present in ~80% of affected individuals (most of whom have >1 type of skin lesion), compared to <3% of the general population; shallow coccygeal dimples and deep gluteal clefts, which are considered as normal variants, occur in an additional 4% of infants.
Skin lesions of the spinal axis associated with dysraphism.
The presence of two or more types of lesions increases the risk of a spinal anomaly.
|Hypertrichosis||A V-shaped patch of long, coarse or silky hair (see Fig. 53.7A,B); ‘faun tail’|
|Lipomas||Soft subcutaneous mass, asymmetric buttocks, curved gluteal cleft (see Fig. 53.7C); most common sign of spinal dysraphism|