What is aplasia cutis congenita?
Aplasia cutis congenita describes the congenital absence of skin. The commonest form presents as a scalp defect at birth. Aplasia cutis is also a component of a number of genetic syndromes.
How do you get aplasia cutis and who is at risk?
Factors contributing to aplasia cutis include:
- Genetics: aplasia cutis may be seen in association with other congenital skin defects such as organoid or epidermal naevi. Familial cases are reported with autosomal dominant and autosomal recessive inheritance.
- Nonsyndromic aplasia cutis congenita has been associated with a heterozygous mutation in the BMS1 gene (611448) on chromosome 10q11.
- Placental infection during pregnancy, such as varicella (chickenpox) or herpes simplex
- Teratogens (drugs or chemicals causing birth deformities, such as methimazole, carbimazole, misoprostol, cocaine, marijuana, and valproic acid)
- Defect in skin development in the embryo/fetus
- Amniotic bands due to early rupture of amniotic membranes
- The death of a twin fetus (papyraceous fetus).
Aplasia cutis is rare and no particular race or sex is at greater risk.
What are the clinical features of aplasia cutis?
In 70–80% of cases, aplasia cutis affects the scalp lateral to the midline, but lesions may also occur on the face, trunk, or limbs, sometimes symmetrically.
- The areas of skin loss or ulceration vary in size from 0.5 cm to 10 cm.
- The defects are non-inflammatory and are well demarcated.
- A tuft of hair surrounding aplasia cutis may denote underlying malformation with neural tube defecT.
- Superficial aplasia cutis involves only the epidermis (upper layers of skin). Shallow defects usually heal over before the child is born, leaving a scar.
- Deeper defects can extend through the dermis, subcutaneous tissue, and rarely periosteum, skull, or dura.
- Aplasia cutis may partially heal before delivery and appear as a hairless, atrophic, membranous, parchmentlike or fibrotic scar.
- Membranous aplasia cutis is a flat, white membrane overlying a defect in the skull. Distorted hair growth, known as the hair collar sign, is a marker for an underlying cranial defect such as encephalocoele, meningocoele, and brain tissue outside the skull.
- A rare bullous variant of aplasia cutis congenita has been reported.
- Some people with aplasia cutis also have congenital malformations of the heart, gastrointestinal, genitourinary (such as gastroschisis or omphalocele), and central nervous systems (such as meningomyelocele or spinal dysraphism).
Classification of aplasia cutis
The Frieden classification system for aplasia cutis has 9 groups based on the number and location of the lesions and associated malformations.
Scalp aplasia cutis congenita without other anomalies
Scalp aplasia cutis congenita with limb anomalies: includes Adams-Oliver syndrome
Aplasia cutis congenita overlying deep embryologic malformation
Stellate aplasia cutis congenita of trunk or limb associated with fetus papyraceous or placental infarct
Epidermolysis bullosa with congenital absence of skin (aplasia cutis congenita of lower limb associated with epidermolysis bullosa (Bart syndrome)
Aplasia cutis congenita of limb without epidermolysis bullosa
Aplasia cutis congenita associated with malformation syndromes including trisomy 13 with large membranous defect (Patau syndrome), Wolf-Hirschhorn syndrome (deletion of the short arm of chromosome 4) with midline scalp defects, Setleis syndrome with bitemporal aplasia cutis congenita and abnormal eyelashes; Johanson-Blizzard syndrome with stellate scalp defects; focal dermal hypoplasia (Goltz syndrome); and others.
What are the complications of aplasia cutis?
Complications of aplasia cutis rarely occur but may include:
- Arterial bleeding
- Secondary wound infection
- Sagittal sinus thrombosis.
- Infection of the brain leading to death.
What treatments are available for aplasia cutis?
Small areas of aplasia cutis usually heal spontaneously over time, forming a hairless scar. To prevent infection gentle cleaning and bland ointments may be used. If infection occurs, antibiotics can be used.
Larger lesions or multiple scalp defects may require surgical repair; sometimes skin or bone grafting may be required. Tissue expanders may be employed.