hemifacial myohyperplasia

Hemifacial myohyperplasia is a developmental disorder that predominantly affects the right side of the face and is most commonly observed in males. The condition is marked by asymmetric enlargement of the facial tissues, resulting in features such as an abnormal jaw shape and a dimpled chin. Although the precise cause remains unclear, research has identified an association with the PIK3CA gene, and the disorder is considered to arise from multifactorial influences. It is very rare, affecting fewer than one in a million individuals, and its presentation may evolve until facial asymmetry stabilizes in late adolescence.

Individuals with hemifacial myohyperplasia typically display distinctive facial asymmetry, with constant findings such as hemifacial hypertrophy and a dimpled chin. Many affected individuals also exhibit ptosis and narrow palpebral fissures, while a deviated nasal septum is noted in a subset of cases. Additional features reported include aspects of neurological involvement such as epilepsy, intellectual disability, and brain enlargement, along with ocular and genitourinary issues, though these occur with variable frequency. Not all individuals experience all features, and severity varies considerably.

The exact cause of hemifacial myohyperplasia remains uncertain; however, variants in the PIK3CA gene have been implicated in conditions involving tissue overgrowth. The condition is classified as multifactorial, indicating that both genetic factors and environmental influences are likely to contribute to its development. Because no clear pattern of familial transmission is observed, families are encouraged to seek genetic counseling to better understand the multifactorial nature of the disorder and its implications.

Currently, management of hemifacial myohyperplasia focuses on supportive care and symptom management since there are no FDA-approved or foundational therapies specifically linked to the condition. Treatment is tailored to the individual and typically involves a multidisciplinary team that may address both functional and cosmetic concerns. Regular follow-up and surveillance are important to monitor any emerging complications, and families are advised to engage in genetic counseling to discuss available management options with their healthcare team.

The long-term outlook for individuals with hemifacial myohyperplasia is variable and largely depends on the severity and range of symptoms present. With current standards of care, many individuals achieve a good quality of life, and the course of the condition may include periods of stability after adolescence. Outcomes described in medical literature continue to evolve as standards of care improve, and families are encouraged to consult specialists and support groups for ongoing guidance. That severity and symptoms vary widely between individuals.