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Macroglossia

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Dysmorphology Presentations/Head and face

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An infant or child whose tongue is too big for the oral cavity, protruding at rest or interfering with feeding and airway. The bedside task is to decide whether the tongue itself is enlarged (true macroglossia from hypertrophy or storage) or whether a small mandible makes a normal tongue look big (relative macroglossia). The diagnostic urgency is the storage-disorder differential plus a few treatable mimics that should not be missed.

Two questions reframe the differential:

  1. True or relative? Relative macroglossia (small jaw, midface, oropharynx) goes with the micrognathia/Down syndrome differential. True macroglossia (intrinsic enlargement) goes with overgrowth, storage, and infiltrative causes.
  2. What is filling the tongue? Muscle hypertrophy (BWS), accumulated glycosaminoglycans (MPS), accumulated glycogen (Pompe), mucinous edema (hypothyroidism), focal mass (lymphatic malformation, hemangioma, neurofibroma), or amyloid (adult).

Overgrowth syndromes

  • Beckwith-Wiedemann syndrome (11p15.5 imprinting disturbance; loss of methylation at IC2, gain of methylation at IC1, paternal UPD, or CDKN1C mutation): macroglossia + omphalocele (or umbilical hernia) + macrosomia + hemihyperplasia + neonatal hypoglycemia + ear creases/pits + Wilms tumor and hepatoblastoma risk. The triad of macroglossia + omphalocele + neonatal hypoglycemia is essentially diagnostic. Wilms surveillance (abdominal ultrasound every 3 months) and AFP screening for hepatoblastoma drive the long-term management.
  • Simpson-Golabi-Behmel syndrome (GPC3, X-linked): overgrowth, macroglossia, polydactyly, embryonal tumors. Less common but similar surveillance posture. (No condition leaf to link.)

Lysosomal storage disorders

Tongue tissue accumulates undegraded substrate.

  • MPS I (Hurler): macroglossia is part of the coarse-features picture, with corneal clouding + dysostosis multiplex + hepatosplenomegaly + cardiac valve disease.
  • MPS II (Hunter): X-linked, macroglossia + coarse facies + no corneal clouding + characteristic ivory pebbling skin.
  • Pompe disease (GSD II) (GAA, AR): infantile-onset cardiomyopathy + profound hypotonia + macroglossia from glycogen accumulation. Acid alpha-glucosidase activity is the diagnostic test; enzyme replacement is most effective when started early.

Endocrine

  • Congenital hypothyroidism: macroglossia + umbilical hernia + prolonged jaundice + hypotonia + open posterior fontanelle. Almost always picked up on newborn screening (TSH); rare missed cases still occur and are completely treatable. Always check the newborn screen on any macroglossic infant.

Chromosomal

  • Down syndrome: technically relative macroglossia (small oral cavity, small midface), but it is the most common encounter and worth naming explicitly.

Focal lesions

  • Lymphatic malformation (lymphangioma): focal enlargement, often with episodes of inflammation/bleeding.
  • Infantile hemangioma: bluish, grows in the first months, involutes over years.
  • Neurofibroma: in a child with neurofibromatosis 1, plexiform neurofibromas can involve the tongue.

Adult-onset

  • Amyloidosis (light chain or transthyretin): macroglossia in an adult is a major diagnostic clue. See transthyretin amyloidosis.
  • Macroglossia + omphalocele + neonatal hypoglycemia → Beckwith-Wiedemann. Initiate Wilms surveillance.
  • Macroglossia + hypertrophic cardiomyopathy + profound hypotonia → infantile Pompe disease. Send GAA activity today; ERT is time-sensitive.
  • Macroglossia + prolonged jaundice + open posterior fontanelle + hypotonia in a newborn → congenital hypothyroidism. Check the screen and the TSH.
  • Macroglossia + coarse facies + hepatosplenomegaly + dysostosis → MPS (I, II most likely). Urine GAGs.
  • Adult-onset macroglossia + cardiac symptoms or carpal tunnel → amyloidosis.
  • Focal asymmetric tongue enlargement → vascular or lymphatic malformation; imaging.

The work-up branches off the bedside hypothesis. A general opening sequence:

  1. Newborn screen review: TSH (congenital hypothyroidism), Pompe (where covered).
  2. Glucose, calcium, AFP: hypoglycemia profile and tumor screening if BWS suspected.
  3. Abdominal ultrasound: omphalocele (BWS), hepatosplenomegaly (MPS, storage), kidney size (BWS, ciliopathies).
  4. Echocardiogram: hypertrophic cardiomyopathy (Pompe), valve disease (MPS).
  5. Urine GAGs and oligosaccharides: MPS family and oligosaccharidoses.
  6. Acid alpha-glucosidase activity (Pompe) in any infant with macroglossia + cardiomyopathy + weakness.
  7. Chromosomal microarray for syndromic dysmorphism.
  8. Methylation studies at 11p15.5 if Beckwith-Wiedemann is the working diagnosis (clinical score from Brioude criteria).
  9. MRI of the tongue for suspected focal mass (lymphatic malformation, neurofibroma).
  • Macroglossia + omphalocele + neonatal hypoglycemia = Beckwith-Wiedemann until proven otherwise. The hypoglycemia is often the first noticed; it can be severe and demands diazoxide or continuous feeds in some infants.
  • Don't miss congenital hypothyroidism. It is the one fully reversible cause; the newborn screen should already have answered it, but verify.
  • Pompe is treatable and time-sensitive. ERT (alglucosidase alfa) started before 6 months of age and before CRIM status complications can change the trajectory. Macroglossia + cardiomyopathy + weakness is the trigger.
  • In an adult, macroglossia is amyloidosis until proven otherwise. Look for cardiac infiltration and a monoclonal protein.