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Types and Classifications of ACC

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Aplasia Cutis Congenita (ACC) is categorized into nine Frieden groups based on physical features. Group 1 is the most common, involving only the scalp. Knowing your baby's specific group helps doctors determine their prognosis, check for underlying health issues, and coordinate specialized care.

Key Takeaways

  • • Aplasia Cutis Congenita is evaluated using the Frieden classification system, which divides the condition into nine distinct groups based on symptoms.
  • • Group 1 is the most common form, accounting for 80% of cases, and involves a skin defect only on the scalp of an otherwise healthy baby.
  • • Group 2 (Adams-Oliver Syndrome) involves scalp defects alongside limb abnormalities, such as shortened or missing fingers and toes.
  • • Group 4 involves skin defects located over deeper skull or brain malformations, requiring close monitoring for infection or bleeding.
  • • Identifying the specific Frieden group is essential for predicting the baby's prognosis, checking for hidden health risks, and coordinating appropriate specialists.

When a doctor diagnoses a baby with Aplasia Cutis Congenita (ACC), they use a specialized framework called the Frieden classification system to understand exactly what they are looking at [1]. This system, which divides ACC into nine distinct groups, is essential because it tells the medical team which risks to look for and how to plan for the baby’s long-term care [2][3].

The Core Frieden Groups

While there are nine groups in total, most cases fall into a few primary categories. Understanding which group your baby belongs to helps clarify their prognosis (the expected outcome) [4].

(Note: Groups 3, 7, 8, and 9 are not listed below because they are exceptionally rare and involve very specific, uncommon genetic or teratogenic associations [2].)

Group 1: Isolated Scalp ACC

This is the most common form, accounting for approximately 80% of all cases [1]. In Group 1, the skin defect occurs only on the scalp, and there are no other associated health problems [2][5]. These babies are otherwise healthy, and the lesion typically heals with standard wound care [4].

Group 2: ACC with Limb Anomalies (Adams-Oliver Syndrome)

In Group 2, the scalp defect is found alongside abnormalities of the hands or feet, such as shortened or missing fingers or toes [6][7]. This combination is known as Adams-Oliver Syndrome [8]. Because this syndrome can sometimes affect the heart or brain, babies in this group require a more detailed evaluation by several specialists [9][10].

Group 4: ACC with Underlying Malformations

This group is identified when the skin defect is located directly over a deeper structural issue, such as a gap in the skull bone or a malformation of the dura (the protective layer around the brain) [2][11]. These cases require careful monitoring because large gaps in the skull can increase the risk of infection or bleeding [12][13].

Group 5: ACC and Fetus Papyraceus

Group 5 is unique because it is related to twin pregnancies. It occurs when one twin stops developing early in the pregnancy (fetus papyraceus) [14][15]. The surviving baby may be born with star-shaped (stellate) skin defects, often located on the trunk or sides of the body rather than the scalp [14][16].

Group 6: ACC and Epidermolysis Bullosa (Bart Syndrome)

When a baby has ACC along with skin that blisters easily or has abnormal nails, it is classified as Group 6, or Bart Syndrome [2][17]. This is caused by a genetic mutation that makes the skin fragile [18]. These babies need specialized care to prevent and treat blisters [1][19].

Why Classification Matters

Determining the correct Frieden Group is the most important step after the initial diagnosis. It allows doctors to:

  • Identify Risks: Some groups (like Group 4) carry a risk of brain-related issues, while others (like Group 1) do not [20][11].
  • Coordinate Care: If a baby is in Group 2 or 6, they may need to see a cardiologist, a geneticist, or a specialized wound care team [21][22].
  • Provide Answers: Knowing the group helps parents understand why the defect happened and what to expect for their child’s future health [13].
Frieden Group Primary Feature Key Association
Group 1 Scalp only Isolated / No other issues
Group 2 Scalp + Limbs Adams-Oliver Syndrome
Group 4 Over deeper defects Skull or CNS malformations
Group 5 Stellate (star) trunk lesions Twin pregnancy (Fetus papyraceus)
Group 6 Skin absence + Blistering Bart Syndrome / Epidermolysis Bullosa

To understand when these conditions pose higher risks, proceed to Warning Signs and Potential Risks.

Frequently Asked Questions

What is the Frieden classification system for ACC?
The Frieden classification system divides Aplasia Cutis Congenita into nine distinct groups based on the location of the missing skin and any other physical features. This helps doctors understand a baby's prognosis, identify potential health risks, and plan their care.
What is the most common type of Aplasia Cutis Congenita?
The most common type is Group 1, also known as Isolated Scalp ACC. It accounts for about 80% of all cases. In this group, the baby is otherwise completely healthy, and the missing patch of skin is located only on the scalp.
Can Aplasia Cutis Congenita affect the skull or brain?
Yes, in Group 4 ACC, the skin defect occurs directly over a deeper structural issue, such as a gap in the skull bone or the protective layer around the brain. These cases require close monitoring to prevent complications like infection or bleeding.
Why might my baby with ACC need to see a cardiologist or geneticist?
Babies diagnosed with certain types of ACC, such as Group 2 (Adams-Oliver Syndrome), may have associated limb, heart, or genetic abnormalities. Seeing specialized doctors ensures any underlying conditions are properly evaluated and managed as part of the baby's long-term care plan.
How is Bart Syndrome related to Aplasia Cutis?
Bart Syndrome, or Group 6 ACC, occurs when a baby is born missing a patch of skin and also has Epidermolysis Bullosa. This underlying genetic mutation makes the baby's skin extremely fragile and prone to severe blistering, requiring specialized wound care.

Questions for Your Doctor

  • • Which Frieden Group does my baby’s condition fall into, and why?
  • • Are there any signs of limb or nail abnormalities that we should be aware of?
  • • Does the location of the lesion (e.g., midline or vertex) suggest we need to check for underlying bone or brain involvement?
  • • Given the classification, what specialists (like a cardiologist or geneticist) should we consult?

Questions for You

  • • Have I noticed any unusual patterns on the baby’s skin, like a marbled or lace-like appearance (cutis marmorata)?
  • • Are the baby’s fingernails or toenails fully formed and healthy-looking?
  • • Are all of the baby's fingers and toes present and of typical length?

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References

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    Classification of aplasia cutis congenita: a 25-year review of cases presenting to a tertiary paediatric dermatology department.

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This page explains the Frieden classification system for Aplasia Cutis Congenita for educational purposes. Always consult your pediatric dermatologist or geneticist for an accurate diagnosis of your baby's specific condition and healthcare needs.

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