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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Craniofacial Surgery

Understanding Hemifacial Hyperplasia

At a Glance

Hemifacial hyperplasia (HFH) is a rare condition where one side of the face grows larger due to increased cell numbers. Often linked to a non-inherited genetic mutation (PROS), the growth usually stabilizes after puberty. Care may involve craniofacial surgery or targeted PI3K inhibitor therapies.

Receiving a diagnosis of a rare facial difference can feel overwhelming, especially when the names for the condition seem to change. Hemifacial Hyperplasia (HFH) is a rare congenital developmental disorder where one side of the face grows more than the other [1][2]. It can affect the skin, muscles, fat, bones, and even the teeth [2][3]. While the rarity of this condition means you may not meet many others with it in your daily life, it is well-documented in medical literature, and specialized craniofacial teams are equipped to support you [2][4].

Understanding the Name Change

In older medical records, you might see the term hemihypertrophy. However, medical experts now prefer the term hyperplasia [5][1]. The difference lies in what is happening at the cellular level:

  • Hypertrophy means the individual cells have grown larger in size [6][7].
  • Hyperplasia means there is an increase in the actual number of cells [6][7].

Research has shown that in this condition, the tissues contain an increased number of cells, making “hyperplasia” the more accurate scientific description [8].

The Role of Genetics

Modern science has linked many cases of facial overgrowth to the PIK3CA-related overgrowth spectrum (PROS) [9][10]. This is an “umbrella term” for several conditions caused by a change (mutation) in the PIK3CA gene [9][11].

Crucially, these mutations are somatic, meaning they happen by chance in a specific cell during early development and are not passed down from parents to children [9][12]. Because the mutation is only in certain parts of the body, doctors often need to test a small sample of the affected tissue rather than just a blood sample to confirm a diagnosis [13][14].

Growth Patterns and Timeline

Every patient’s journey is unique, but HFH typically follows a recognizable growth pattern:

  1. At Birth: The asymmetry is usually present when a child is born, though it may be subtle at first [2][4].
  2. Childhood and Puberty: The affected side often grows at a faster or “exponential” rate compared to the unaffected side [2][4]. This difference often becomes much more noticeable during the growth spurts of puberty [2][15].
  3. Adulthood: For many, the overgrowth stabilizes once they reach skeletal maturity (when the “growth plates” close after puberty) [2][16].

Note on Progression: While many cases stabilize, some specific forms—such as Congenital Infiltrating Lipomatosis of the Face (CIL-F)—can continue to show progressive growth into adulthood [17][16]. Your medical team will monitor for “active” growth to determine if and when surgical interventions, such as those involving the jaw joint (TMJ), may be necessary [2][16][18].

Looking Forward

Living with a visible difference can take an emotional toll. It is important to remember that having a clear diagnosis is the first step toward effective management. Current research is even exploring “targeted therapies” (like PI3K inhibitors) that may help manage overgrowth by addressing the underlying genetic cause, providing new avenues for care beyond traditional surgery [19][20].

Common questions in this guide

What is the difference between hemifacial hyperplasia and hemihypertrophy?
Hypertrophy means individual cells grow larger, while hyperplasia means there is an increase in the total number of cells. Medical experts now prefer the term hyperplasia because research shows the condition involves an increased number of cells rather than just larger ones.
Is hemifacial hyperplasia passed down from parents to children?
No, the genetic mutations that cause hemifacial hyperplasia happen by chance in a specific cell during early fetal development. Because these are somatic mutations, they are not inherited from your parents and you cannot pass them to your children.
Will the facial overgrowth keep getting worse?
The affected side usually grows faster during childhood and puberty, but for many patients, it stabilizes once they reach skeletal maturity in adulthood. However, some specific forms can continue to grow, so your medical team will monitor you closely for active growth.
Why do I need a tissue biopsy for genetic testing instead of a blood test?
Because the genetic changes that cause the condition are localized to the overgrown areas, a standard blood test is often not enough. Doctors typically need to test a small sample of the affected tissue to find the specific mutation and confirm the diagnosis.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my symptoms and history, does my condition fall within the PIK3CA-Related Overgrowth Spectrum (PROS)?
  2. 2.Have you performed genetic testing on a tissue sample from the affected side? If not, would that help clarify my diagnosis?
  3. 3.Is the overgrowth currently stable, or are there signs that it is still actively growing?
  4. 4.What specialists (such as craniofacial surgeons, orthodontists, or geneticists) should be on our care team?
  5. 5.Are there any functional risks to my jaw (TMJ), teeth, or breathing that we should be monitoring?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (20)
  1. 1

    Hemifacial hypertrophy: Exploring new avenues of treatment modalities.

    Nandimath SA, Rajkumar GC, Nayak T, et al.

    National journal of maxillofacial surgery 2016; (7(1)):100-104 doi:10.4103/0975-5950.196123.

    PMID: 28163490
  2. 2

    Hemifacial hyperplasia: a case series and review of the literature.

    Dattani A, Heggie A

    International journal of oral and maxillofacial surgery 2021; (50(3)):341-348 doi:10.1016/j.ijom.2020.05.008.

    PMID: 32622511
  3. 3

    Congenital infiltrating lipomatosis of the face: A subtype of hemifacial hyperplasia.

    Sun R, Sun L, Li G, et al.

    International journal of pediatric otorhinolaryngology 2019; (125()):107-112 doi:10.1016/j.ijporl.2019.06.032.

    PMID: 31280031
  4. 4

    Congenital Hemifacial Hyperplasia: Clinical Presentation and Literature Review.

    Shanmugasundaram K, Vedam VK, Ganapathy S, et al.

    Case reports in dentistry 2016; (2016()):5260645 doi:10.1155/2016/5260645.

    PMID: 27843653
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    Hemifacial Hyperplasia.

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    Contemporary clinical dentistry 2017; (8(2)):327-331 doi:10.4103/ccd.ccd_113_17.

    PMID: 28839423
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    Postnatal Exocrine Pancreas Growth by Cellular Hypertrophy Correlates with a Shorter Lifespan in Mammals.

    Anzi S, Stolovich-Rain M, Klochendler A, et al.

    Developmental cell 2018; (45(6)):726-737.e3 doi:10.1016/j.devcel.2018.05.024.

    PMID: 29920277
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    Elevated levels of Drosophila Wdr62 promote glial cell growth and proliferation through AURKA signalling to AKT and MYC.

    Shohayeb B, Mitchell N, Millard SS, et al.

    Biochimica et biophysica acta. Molecular cell research 2020; (1867(7)):118713 doi:10.1016/j.bbamcr.2020.118713.

    PMID: 32246948
  8. 8

    Missense mutation in the PTEN promoter of a patient with hemifacial hyperplasia.

    Yamazaki K, Eng C, Kuznetsov SA, et al.

    BoneKEy reports 2015; (4()):654 doi:10.1038/bonekey.2015.21.

    PMID: 26229595
  9. 9

    Phenotypic heterogeneity in PIK3CA-related overgrowth spectrum.

    Vahidnezhad H, Youssefian L, Baghdadi T, et al.

    The British journal of dermatology 2016; (175(4)):810-4 doi:10.1111/bjd.14618.

    PMID: 27037860
  10. 10

    PIK3CA vascular overgrowth syndromes: an update.

    Hughes M, Hao M, Luu M

    Current opinion in pediatrics 2020; (32(4)):539-546 doi:10.1097/MOP.0000000000000923.

    PMID: 32692051
  11. 11

    Lymphangioma of the fetal neck within the PIK3CA-related-overgrowth spectrum (PROS): A case report.

    Scharf JL, Gembicki M, Dracopoulos C, et al.

    Clinical case reports 2021; (9(7)):e04527 doi:10.1002/ccr3.4527.

    PMID: 34306701
  12. 12

    Unilateral condylar hyperplasia in hemifacial hyperplasia, is there genetic proof of overgrowth?

    Nolte JW, Alders M, Karssemakers LHE, et al.

    International journal of oral and maxillofacial surgery 2020; (49(11)):1464-1469 doi:10.1016/j.ijom.2020.02.002.

    PMID: 32249036
  13. 13

    PIK3CA-related overgrowth with an uncommon phenotype: case report.

    Rotunno R, Diociaiuti A, Pisaneschi E, et al.

    Italian journal of pediatrics 2022; (48(1)):71 doi:10.1186/s13052-022-01268-9.

    PMID: 35551640
  14. 14

    Phenotypic and molecular characterization of five patients with PIK3CA-related overgrowth spectrum (PROS).

    Gökpınar İli E, Taşdelen E, Durmaz CD, et al.

    American journal of medical genetics. Part A 2022; (188(6)):1792-1800 doi:10.1002/ajmg.a.62709.

    PMID: 35238469
  15. 15

    Hemifacial hypertrophy - Report of 2 cases.

    Balaji SM, Balaji P

    Indian journal of dental research : official publication of Indian Society for Dental Research 2022; (33(3)):344-347 doi:10.4103/ijdr.ijdr_688_22.

    PMID: 36656200
  16. 16

    Temporomandibular Joint Prosthesis in a Patient with Congenital Infiltrating Lipomatosis of the Face with Bony Ankylosis of the Temporomandibular Joint: A Case Report.

    Bulthuis LCM, Ho JPTF, Zuurbier PCM, et al.

    Journal of clinical medicine 2023; (12(24)) doi:10.3390/jcm12247723.

    PMID: 38137792
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    Advances in the Treatment of Congenital Infiltrating Lipomatosis of the Face: The Role of PIK3CA Mutations and Microvascular Reconstruction.

    Moreno SD, Liu RH, Robbins Q, Burkes J

    The Journal of craniofacial surgery 2025; (36(1)):229-233 doi:10.1097/SCS.0000000000010751.

    PMID: 39724639
  18. 18

    Congenital infiltrating lipomatosis of the face with temporomandibular joint ankylosis.

    Gupta R, Mukul SK, Kumar P, Kumar A

    National journal of maxillofacial surgery 2020; (11(1)):117-120 doi:10.4103/njms.NJMS_59_17.

    PMID: 33041589
  19. 19

    Treatment of two infants with PIK3CA-related overgrowth spectrum by alpelisib.

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    Alpelisib for the treatment of PIK3CA-related head and neck lymphatic malformations and overgrowth.

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    PMID: 36066547

This page provides educational information about hemifacial hyperplasia and PROS. It does not replace professional medical advice, and you should always consult a specialized craniofacial team or geneticist regarding diagnosis and treatment.

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