Aplasia Cutis Congenita

3 Interesting Facts of Aplasia Cutis Congenita

1. Aplasia cutis congenita (APC) is an uncommon disorder (~3 cases/100,000 births) but is the most common cause of a congenital scarring alopecia.
2. No treatment is required. Conservative intervention, particularly to promote healing when ulceration is present, includes topical petrolatum, silver sulfadiazine cream, or dressings that contain epidermal growth factor.
3. APC is a permanent condition that will demonstrate mature scar with time. In most cases, any bone defects will spontaneously close.

Etiology and Risk Factors

• The mechanism is poorly understood, but the presence of familial cases of APC—autosomal dominant and autosomal recessive variants exist—suggests a genetic basis (OMIM 10760). In one family, the defect was linked to a mutation in the BMS1 gene on chromosome 10.
• APC is also a component of several syndromes, including Johanson-Blizzard syndrome, Adams-Oliver syndrome, Wolf-Hirschhorn syndrome, epidermolysis bullosa, and trisomy 13.
• Intrauterine infection with herpes simplex virus and varicella-zoster virus has been implicated in some cases.
• Certain drugs, including cocaine, marijuana, valproic acid, methimazole, carbimazole, and misoprostol, have also been linked to the development of APC.
• Some cases of APC have been associated with fetus papyraceus (so-called vanishing twin).

Diagnosis

Approach to Diagnosis

• The diagnosis is usually made on clinical grounds, with observation of focal scarring, devoid of hair, on the vertex of a newborn.

Workup

Physical Examination

• APC is present at birth.
• Most cases involve the vertex of the scalp, usually just lateral to the midline (~70% of cases). Other sites less often involved include the back and extremities.
• APC may be a solitary condition (70% of cases), or lesions may be multiple (30% of cases).
• Lesions of APC may be round or oval and linear or stellate and range in size from 0.5 cm to more than 10 cm.
• There may be absence of all skin or simply partial loss. Complete hair loss is usually present within atrophic areas.
• The surface may be shiny, with a thinned or scaly surface, or there may be an ulcer. In rare cases, the surface may appear bullous.
• Some lesions may demonstrate a so-called hair collar sign, with a ring of longer, darker hair that surrounds the area of hair loss. Patients with a hair collar sign are more likely to have underlying defects of bone or neurologic abnormalities (e.g., meningomyelocele, porencephaly).
• Patients may have underlying bony or neurologic defects.

Imaging Studies

• Select cases should have imaging studies to evaluate for underlying bony or neural defects.

Treatment

Nondrug and Supportive Care

• No treatment is required. Conservative intervention, particularly to promote healing when ulceration is present, includes topical petrolatum, silver sulfadiazine cream, or dressings that contain epidermal growth factor.

Treatment Procedures

• Select cases can be treated with surgical intervention. Cases with underlying bone defects are best managed by a multidisciplinary team of neurosurgeons and plastic surgeons.

References

Duan X, Yang GE, Dongqu Y, Changlong Y, Wang B, Guo Y. Aplasia cutis congenita: A case report and literature review. Experimental and therapeutic medicine. 2015;10(5):1893-1895.