December 2005

This full-term newborn was noted at birth to have a bullous lesion on the scalp. The lesion was nontender, and there was no drainage. The hair was absent within the lesion, and the hair formed a collarette around the involved area. The prenatal history was unremarkable. The infant had a normal neurological examination, normal temperature and had normal feeding. What is this lesion?

Answer

The diagnosis is aplasia cutis congenita. This entity occurs in one per 3,000 to 10,000 births. It is most commonly seen on the scalp, particularly near the vertex. The lesions may be bullous (as in this child), ulcerated or present as an atrophic scar. Aplasia cutis congenita can occur on any area of the body. Some familial cases have been reported; however, most occur sporadically.

If a biopsy is done, it shows absence of the epidermis and dermal appendages.

The treatment is primarily observation. Many of the lesions heal with a small atrophic scar, which tends to have little cosmetic significance. It is important to avoid secondary infection especially in the open lesions. When the bulla or vesicle is intact, trauma should be avoided to minimize rupture.

Some lesions may be treated with surgical excision to remove the alopetic patch.

If the lesion is located on the midline, it may represent a small subset of these lesions, which, in fact, are neuroectodermal defects. If a midline lesion is noted especially involving ventral surfaces, imaging may help to disclose central nervous system involvement.

The differential diagnosis includes a neuroectodermal defect as mentioned above; herpes simplex; traumatic injury (ie, from the fetal scalp probe, forceps or vacuum suction); or focal dermal hypoplasia.

For more information:

• Baselga E, Torrelo A, Drolet BA, et al. Familial nonmembranous aplasia cutis of the scalp. Pediatr Dermatol. 2005;22:213-217.
• Bernbeck B, Schwabe J, Groninger A, et al. Aplasia cutis congenita of the scalp: how much therapy is necessary in large defects? Acta Paediatr. 2005;94:758-760.
• Atik B, Tan O, Bayram I, et al. Asymmetrical nonscalp aplasia cutis congenita: a case report. J Dermatol. 2004;31:923-926.
• Drolet B, Prendiville J, Golden J, et al. ‘Membranous aplasia cutis’ with hair collars. Congenital absence of skin or neuroectodermal defect? Arch Dermatol. 1995;131:1427-1431.