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Most-often inherited disorder with circumscribed or
more extensive skin lesions that also may involve underlying tissues.
Neurologic and cardiac anomalies have been described.
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Congenital Scalp Defect; Congenital Defects of Skull and
Scalp.
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More than 500 cases have been described in the
literature. No racial or sexual predilection has been reported.
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Autosomal dominant with great expression
variability. However, autosomal recessive and sporadic cases also have been
reported.
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Beside genetic factors, several other mechanisms
probably are involved. Amniotic bands resulting from early rupture of the
amniotic membranes are considered responsible for a couple of cases of
aplasia cutis congenita (ACC). Other mechanisms discussed in the
pathogenesis of this disorder are environmental factors (e.g., toxins and
teratogens [maternal cocaine abuse, misoprostol, methimazole during
pregnancy], intrauterine infections) and early embryonic vascular
abnormalities with compromised blood flow to a circumscribed area of the
skin.
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Based on clinical findings. Skin lesions can occur
anywhere on the body but are found most often on the scalp. More than 80%
of solitary lesions are found on the scalp.
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Noninflammatory and well-demarcated lesions have
different shapes, with diameters ranging from 0.5 to 10 cm and dilated scalp
veins radiating from the periphery of scalp defect. The defect often is
located in the area of the vertex of the skull. In a few cases, almost
complete absence of skin and skull bone (partial acrania) has been reported
and associated with high mortality (infection, hemorrhage). The aspect
of the lesions is quite variable because it depends upon the stage of
uterine development when the insult occurs. Defects caused early in
gestation may be healed before birth and appear as an atrophic transparent
membrane or a fibrotic scar. However, defects that develop later in
gestation may present as ulcerations of variable depth. Although most
defects are limited to the epidermis, occasionally the ulcerations are deep
and involve the underlying subcutaneous, periosteal, and osseous tissues or
even the meninges. On the scalp, the alopecic and scarred area usually is
surrounded by a rim of abnormal hair growth, known as the hair collar sign. Small defects
usually heal under formation of an atrophic scar, and underlying osseous
lesions close spontaneously within the first year of life. However,
extensive or multiple lesions may require surgical excision and plastic
surgery (skin grafting, tissue expanders, flaps) to close the defects. Aside
from the formation of atrophic scars, truncal and limb defects heal
surprisingly well. Other findings may include chest with pectus excavatum,
supernumerary nipples, and Poland Syndrome. Congenital cardiac lesions,
such as tetralogy of Fallot, pulmonary valvular atresia, and ventricular
septal defects, have been described in some patients. Various neurologic
anomalies include mental retardation, seizures, spasticity, hemiparesis,
encephalocele or exencephaly, porencephaly, and ...