▶Aplasia cutis congenita (ACC) is a congenital defect of the skin that results in localized absence of the epidermis, dermis, and, occasionally, subcutaneous tissue.
▶The cause is unknown and most cases are sporadic, although autosomal dominant inheritance has been suggested in some reports. A link with maternal antithyroid medication (especially methimazole) use during pregnancy has been suggested.
▶Aplasia cutis congenita is a feature of Adams-Oliver (with transverse limb defects and vascular and cardiac abnormalities) and oculocerebrocutaneous (Delleman) syndromes and may occur in those who have trisomy 13 syndrome.
▶Usually presents as a solitary, round, oval, or stellate-shaped, 1- to 2-cm ulcer (Figure 95.1) or scar (Figure 95.2) located on the scalp near the origin of the hair whorl (although other body sites occasionally are affected). A minority of patients have multiple lesions (typically 2 or 3).
▶In some patients, the defect is covered by a thin membrane and surrounded by long dark hairs (the hair collar sign; Figure 95.3). This membranous form of ACC is postulated to represent a mild form of cranial neural tube closure defect.
▶Large lesions (>4 cm) may be associated with underlying skull defects that may predispose to sagittal sinus hemorrhage or thrombosis, local infection, or meningitis.
Look-alikes
Disorder | Differentiating Features |
When Presenting as an Ulcer | |
Herpes simplex virus infection | •Usually presents as clustered vesicles on an erythematous base (not a solitary large ulcer). •Lesions usually not present at birth. |
Trauma from forceps | •May cause a scalp erosion (more superficial than an ulcer), and shape and location likely to be different than seen in ACC. |
Trauma from scalp electrode | •Usually produces an erosion (more superficial than an ulcer) and is typically smaller than ACC. |
Epidermolysis bullosa | •Typically more superficial than ACC, with denudation and eroded patches. •Usually presents with multiple sites of involvement. •Oral mucosal involvement occasionally present. |
When Presenting as a Scar | |
•Usually presents as a verrucous (warty) plaque; however, some lesions are quite flat in neonates and may mimic a scar. •Often yellow-orange to tan in color. •If left untreated, texture becomes more elevated and verrucous in the peripubertal and postpubertal years. | |
▶The diagnosis is usually made clinically based on the appearance of the lesion(s).
▶For small ulcers, local wound care to prevent secondary bacterial infection is sufficient. Lesions presenting as scars require no treatment.
▶Large lesions require plastic surgery consultation and imaging.
▶Excellent for small lesions; atrophic scars will persist and ulcers will heal with atrophic scars. Large lesions may be associated with underlying skull defects that may predispose to sagittal sinus hemorrhage or thrombosis, local infection, or meningitis. For such patients, plastic surgical consultation is recommended.
▶Obtain plastic surgery consultation and consider imaging (for underlying central nervous system involvement) for patients with large lesions or deeper involvement. Also consider imaging for lesions accompanied by vascular stains or nodules, or those with an associated hair collar sign (due to the risk of associated neural tube defect).
▶Genetics Home Reference: Nonsyndromic aplasia cutis congenita.
http://ghr.nlm.nih.gov/condition/nonsyndromic-aplasia-cutis-congenita