Aplasia cutis

Aplasia cutis a naevoid abnormality which may present as absent areas of epidermis - ulceration - on the scalp

• it is sometimes associated with skull defects and brain abnormalities (1)
• lesions are often mistakenly thought to have been caused by birth trauma, and generally heal with a resultant atrophic scar - a bald patch

These lesions are often mistakenly thought to have been caused by birth trauma, and generally heal with a resultant atrophic scar - a bald patch.

Lesions present as well demarcated, noninflammatory, circular or oval blister or as an eroded region and are typically seen at the scalp vertex just lateral to the midline (1). Occasionally lesions can be seen on the trunk and on the extremities as well (2)

• the lesions may present as a solitary lesion (70% of cases) or as multiple lesions (1-2cm in diameter) (1)
• appearance of the lesion differs according to the gestational time period the lesion occurred:
  • Early in gestation: may heal before delivery and may present as atrophic, fibrotic, alopecic scars
  • Later in gestation: presents as an ulcer Hair collar sign (hair growth around the scalp lesion is distorted) is considered to be a marker of an underlying defects (1)

Associated congenital malformation may be seen in larger lesions. This condition may also be associated:

• with the use of carbimazole during pregnancy
• with Patau's syndrome

Management is usually conservative in small ulcers since they are self limiting (ulcers heal with scars over several weeks and bone defects close during the first year of life) Due to the risk of hemorrhage and infection multiple and large ulcers need excision and surgical closure.

Complications of aplais cutis include

• meningitis
• haemorrhage
• local infection (1)

Click here for an example image of this condition

Reference:

• 1. Buchel T et al. Photo quiz - New born with a scalp lesion. AFP 2005;72(8)
• 2. Jones C.H, Andrews C. Picture of the Month-Diagnosis. Arch Pediatr Adolesc Med. 2005;159:1128