A 5-year-old child presents with impaired attention, memory deficits, borderline intellectual functioning, and dysmorphic features including smooth philtrum, thin upper lip, small palpebral fissures (short), and small head circumference. Maternal history reveals heavy alcohol consumption throughout pregnancy. Which feature is PATHOGNOMONIC for Fetal Alcohol Syndrome (FAS)?
- A Intellectual disability and growth restriction (these are present in many conditions)
- B Cardiac defects (ASD/VSD) plus microcephaly
- C The sentinel facial features: smooth philtrum + thin vermilion border + short palpebral fissures, in combination with confirmed prenatal alcohol exposure ✓
- D Cerebellar hypoplasia on MRI
Explanation
The diagnostic criteria for Fetal Alcohol Syndrome (FAS) require all three sentinel facial features: (1) smooth philtrum (absent philtrum ridges), (2) thin vermilion border of the upper lip, and (3) small palpebral fissures — PLUS evidence of prenatal alcohol exposure AND at least one of: growth deficiency, CNS abnormalities (structural, neurological, or functional including intellectual disability). The facial features are pathognomonic only in combination with documented alcohol exposure. Cardiac defects and cerebellar abnormalities can occur in FAS but are not diagnostic. These three facial features are highly specific to ethanol teratogenicity (acetaldehyde effect on midface development).
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.