Aplasia Cutis Congenita

Most-often inherited disorder with circumscribed or more extensive skin lesions that also may involve underlying tissues. Neurologic and cardiac anomalies have been described.

(Figure)

Congenital Scalp Defect; Congenital Defects of Skull and Scalp.

More than 500 cases have been described in the literature. No racial or sexual predilection has been reported.

Autosomal dominant with great expression variability. However, autosomal recessive and sporadic cases also have been reported.

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.

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.

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 ...