What is macroglossia?
Macroglossia is an abnormal enlargement of the tongue . It is a clinical diagnosis defined as tongue protrusion beyond the teeth or alveolar ridge during resting posture. It can exist in isolation or in association with other conditions or syndromes .
It can be classified into two main categories :
- True macroglossia, a true enlargement of the tongue
- Relative macroglossia (also called pseudomacroglossia), where a normal-sized tongue appears large relative to adjacent anatomical structures.
Macroglossia due to amyloidosis
Who gets macroglossia?
Macroglossia is most often diagnosed in infants and children . The prevalence of congenital macroglossia was reported to be fewer than 5 per 100,000 births, twice as common in females than males, and twice as common in African Americans compared to those of European ancestry .
True macroglossia can be congenital or acquired [1,2].
Conditions associated with congenital true macroglossia include [1,4]:
- Vascular malformation
- Lymphatic malformation
- Infantile haemangioma
- Idiopathic muscular hypertrophy and hemihypertrophy
- Beckwith-Wiedemann syndrome
- Mucopolysaccharidoses (Hunter syndrome and Hurler syndrome)
- Becker muscular dystrophy and Duchenne muscular dystrophy
- Neurofibromatosis type 1
- Multiple endocrine neoplasia type 2B.
Acquired macroglossia is usually due to metabolic or inflammatory conditions, such as:
- Systemic amyloidosis
- Trauma and surgical procedures
- Radiation therapy
- Amyotrophic lateral sclerosis.
Relative macroglossia is commonly due to Down syndrome . It can also occur because of tonsillar hypertrophy or a tumour which pushes the tongue forwards, or reduced oral cavity volume from a low palatal vault .
What causes macroglossia?
The cause of macroglossia is dependent on any underlying condition. For example:
- A congenital vascular malformation extends into the body of the tongue
- Abnormalities in the expression of genes on chromosome 11n cause muscular hyperplasia in Beckwith-Wiedemann syndrome
- Macroglossia occurs in Hurler syndrome and Hunter syndrome through abnormal glycogen storage
- Abnormal deposition of amyloid protein causes macroglossia in amyloidosis
- Macroglossia results from muscular atrophy and subsequent fatty replacement in myasthenia gravis and amyotrophic lateral sclerosis .
What are the clinical features of macroglossia?
The clinical features of macroglossia vary according to the underlying cause and can range from mild to severe .
- The enlarged tongue extends beyond the teeth or alveolar ridge at rest.
- The tip of the tongue can often be extended to the nose and chin.
- Beckwith-Wiedemann syndrome, hypothyroidism, and acromegaly cause generalised enlargement of the tongue with a smooth surface.
- Amyloidosis, neurofibromatosis, and multiple endocrine neoplasia, type 2B, cause generalised enlargement with a multinodular surface.
- A lymphatic malformation causes focal enlargement with a pebbly surface and multiple vesicle-like blebs.
- A tumour or a proliferative haemangioma causes focal enlargement.
- Hemihypertrophy describes unilateral enlargement.
What are the complications of macroglossia?
Complications of macroglossia include:
- Ulceration (Riga-Fede disease) and secondary infection due to constant protrusion of the tongue
- An open bite, crenation on the lateral border of the tongue, teeth spacing, and mandibular protrusion 
- A narrowed airway which can cause noisy breathing, drooling, obstructive sleep apnoea, and in severe cases, airway obstruction 
- Difficulty with speech and articulation
- Difficulty in chewing and swallowing, which can negatively affect nutrition, particularly for infants and older people and cause temporo-mandibular joint pain .
How is macroglossia diagnosed?
Macroglossia is diagnosed clinically [1,2].
In utero, an ultrasound scan can detect macroglossia . X-rays can be used to determine the size of the tongue when primarily used to measure the size of the head.
Diagnosis of any underlying condition is also important. Tests may include gene analysis, biopsy, or fine needle aspiration (FNA) .
What is the differential diagnosis for macroglossia?
The main differential diagnosis for true macroglossia is relative macroglossia.
What is the treatment for macroglossia?
The treatment for macroglossia depends on the underlying cause. Congenital macroglossia can resolve as the child grows, as the tongue and oral cavity adapt to accommodate the larger tongue .
In general, treatment involves the following :
- Management of the underlying systemic disease (if any)
- Surgery — glossectomy may be required in less than 10% of cases for severe macroglossia or its complications [1,2]
- Treatment of secondary orthodontic abnormalities.
What is the outcome for macroglossia?
The prognosis for patients with macroglossia is highly dependent on the severity, the underlying cause, and the success of treatment.