Facial infiltrating lipomatosis

Facial infiltrating lipomatosis (FIL), also referred to as congenital infiltrating lipomatosis of the face or facial infused lipomatosis, is an ultra-rare craniofacial overgrowth condition caused by a genetic mutation of the PIK3CA gene.[1] The condition is a part of the PIK3CA related overgrowth spectrum (PROS).[2] The disease is congenital and non-hereditary. First described by Slavin and colleagues in 1983.[3]

Facial infiltrating lipomatosis
Other namesCongenital infiltrating lipomatosis of the face
Dutch blogger and YouTuber Wilma Westenberg suffers from FIL
Causesgenetic mutation of the PIK3CA gene

For this disease the mutation causes overgrowth of half of the face (hemifacial). It affects both soft and hard tissue (facial skeleton). The condition is noticeable at birth by the asymmetrical cheeks, with one cheek being prominently larger than the other.[4]

Signs & symptoms

Congenital hemifacial enlargement in which mature lipocytes invade adjacent tissue. Phenotypic features include soft-tissue and skeletal hypertrophy and regional macrodontia. The manifestations are variable ranging from mild to severe. The overgrowth is typically present at birth. The most common features, all features on only one affected side of the face, are:[5][4]

Not all patients with facial infiltrating lipomatosis have all these symptoms.

Cause

Mutations in the PIK3CA gene have been identified as the cause for facial infiltrating lipomatosis.[6][4] The mutation is de novo and mosaic meaning it's new, not inherited and not occurring in every cell. One of the DNA nucleotides was altered, causing a change in the amino acid put being into the protein, referred to as a missense mutation, and for PROS, this gives an overactivity, "gain-of-function". The gene is a part of PI3K-AKT/mTOR pathway, a pathway crucial to cell growth, survival, angiogenesis and proliferation.

Illustration of the PIK3CA Related Overgrowth Spectrum

Treatment

There is no cure for FIL/PROS. Management usually consists of multiple debulking surgeries and/or drug treatment. Due to the infiltrating fat in important facial structures complete excision of the overgrowth is often impossible and there is a high risk of regrowth after resection.[4]

The current drug treatment options are either a mTOR inhibitor, a pan AKT (AKT1-2-3) inhibitor or a PIK3CA inhibitor. The mTOR inhibitor is an off-label use, the use of the AKT-inhibitor is currently in a clinical trial[7] (MOSAIC) and the PIK3CA inhibitor is only available through compassionate use program[8] (if one is eligible).

References
  1. Maclellan, Reid A.; Luks, Valerie L.; Vivero, Matthew P.; Mulliken, John B.; Zurakowski, David; Padwa, Bonnie L.; Warman, Matthew L.; Greene, Arin K.; Kurek, Kyle C. (January 2014). "PIK3CA Activating Mutations in Facial Infiltrating Lipomatosis". Plastic and Reconstructive Surgery. 133 (1): 12e–19e. doi:10.1097/01.prs.0000436822.26709.7c. PMID 24374682. S2CID 23828181.
  2. Keppler-Noreuil, Kim M.; Rios, Jonathan J.; Parker, Victoria E.R.; Semple, Robert K.; Lindhurst, Marjorie J.; Sapp, Julie C.; Alomari, Ahmad; Ezaki, Marybeth; Dobyns, William; Biesecker, Leslie G. (February 2015). "PIK3CA-related overgrowth spectrum (PROS): diagnostic and testing eligibility criteria, differential diagnosis, and evaluation". American Journal of Medical Genetics Part A. 167 (2): 287–295. doi:10.1002/ajmg.a.36836. PMC 4480633. PMID 25557259.
  3. Slavin, Sumner A.; Baker, Daniel C.; McCarthy, Joseph G.; Mufarrij, Amjad (August 1983). "Congenital Infiltrating Lipomatosis of the Face". Plastic and Reconstructive Surgery. 72 (2): 158–164. doi:10.1097/00006534-198308000-00006. PMID 6192455. S2CID 28264156.
  4. Li, Yatong; Chang, Guojing; Si, Loubin; Zhang, Hailin; Chang, Xiaoyan; Chen, Zhixiong; Huang, Jiuzuo; Bai, Ming; Wang, Yang; Long, Xiao; Zhao, Ru; Wang, Xiaojun (2018). "Congenital Infiltrating Lipomatosis of the Face". Annals of Plastic Surgery. 80 (1): 83–89. doi:10.1097/SAP.0000000000001213. PMC 5737463. PMID 28846548.
  5. Shenoy, Archana R.; Nair, Keerthi K.; Lingappa, Ashok; Shetty, K. Sadashiva (1 April 2015). "Congenital infiltrating lipomatosis of face: Case report and review of literature". Journal of Indian Society of Pedodontics and Preventive Dentistry. 33 (2): 156–60. doi:10.4103/0970-4388.155134. PMID 25872637.
  6. Couto, Javier A.; Vivero, Matthew P.; Upton, Joseph; Padwa, Bonnie L.; Warman, Matthew L.; Mulliken, John B.; Greene, Arin K. (October 2015). "Facial Infiltrating Lipomatosis Contains Somatic PIK3CA Mutations in Multiple Tissues". Plastic and Reconstructive Surgery. 136: 72–73. doi:10.1097/01.prs.0000472371.96995.e5.
  7. Clinical trial number NCT03094832 for "Study of ARQ 092 in Subjects With PIK3CA-related Overgrowth Spectrum and Proteus Syndrome (MOSAIC)" at ClinicalTrials.gov
  8. Clinical trial number NCT04085653 for "Managed Access Program (MAP) to Provide Alpelisib (BYL719) for Patients With PIK3CA-Related Overgrowth Spectrum (PROS)" at ClinicalTrials.gov
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