Hemifacial hyperplasia or hemifacial hypertrophy is a rare developmental anomaly characterized by asymmetric growth of hard and soft tissues of the face 1.
These asymmetries are often noted at birth and are usually accentuated with increasing age, especially around puberty 2.
The disorder occurs more commonly in females (ratio 3:2) 1.
Various theories have been proposed. These include vascular lymphatic, hormonal, and asymmetric development of the neural fold, with hyperplasia of neural crest cells 3.
It is a condition that appears to affect the derivatives of the first pharyngeal arch, though the middle ear structures seem spared 3.
Hemifacial hypertrophy (HFH) is classified as 4:
- true hemifacial hypertrophy (THFH): unilateral viscerocranial enlargement
- partial hemifacial hypertrophy (PHFH): not all structures are enlarged
Unilateral enlargement of all the viscerocranial structures bounded by the frontal bone, excluding the eye; inferiorly by the inferior border of the mandible and the midline; and laterally by the ear.
Enlargement and deformity of all tissue of the face, including teeth and their related tissues in the jaw, are the key findings in the diagnosis of hemifacial hypertrophy 5.
Isolated hemifacial hyperplasia is a diagnosis of exclusion, because there are other conditions that can cause facial asymmetry including 1:
- Proteus syndrome
- Beckwith-Wiedemann syndrome
- neurofibromatosis type 1
- vascular malformations such as Klippel-Trenaunay syndrome and lymphaticovenous malformations
History and etymology
Hemifacial hyperplasia was first mentioned by Meckel in 1822 4.
- 1. Arora PC, Umarji HR, Arora A, Ramaswami E. Lipomatosis: a diverse form of hemifacial hyperplasia. Imaging science in dentistry. 42 (3): 191-5. doi:10.5624/isd.2012.42.3.191 - Pubmed
- 2. Peter P. Urban, Bruening Roland. Congenital isolated hemifacial hyperplasia. Journal of Neurology. 256 (9): 1566. doi:10.1007/s00415-009-5148-9
- 3. P. Bou-Haidar, P. Taub, P. Som. Hemifacial Lipomatosis, a Possible Subtype of Partial Hemifacial Hyperplasia: CT and MR Imaging Findings. American Journal of Neuroradiology. 31 (5): 891. doi:10.3174/ajnr.A1857 - Pubmed
- 4. Purwar RS. Neurohistological and histochemical observations on the lung of Rattus rattus rufescens (Indian black rat). Acta anatomica. 93 (3): 321-7. Pubmed
- 5. Deshingkar SA, Barpande SR, Bhavthankar JD. Congenital hemifacial hyperplasia. Contemporary clinical dentistry. 2 (3): 261-4. doi:10.4103/0976-237X.86492 - Pubmed