1. Cerebral Lipiodol Embolism following Lymphatic Embolization for Plastic Bronchitis: Utility of Dual Energy CT
Arastoo Vossough, M.D., Ph.D.
Matthew P. Kirschen, M.D., Ph.D.
Daniel J. Licht, M.D.
Rebecca Ichord, M.D.
Children’s Hospital of Philadelphia
University of Pennsylvania

2. Purpose
To demonstrate the CT and MRI imaging findings of the extremely rare entity of hemifacial myohyperplasia

3. Case Presentation
5 year old male with a left cheek and paranasal mass along the nasofacial crease
Initial evaluation at an outside institution due to facial asymmetry at three months of age
Subsequent biopsy of the superficial paranasal and cheek mass
Normal fat and striated muscle
Minimal focal myositis, but otherwise unremarkable striated muscle cells.

4. Clinical Presentation
Initially presented at our institution at 24 months with the presumed clinical diagnosis of hemifacial microsomia
Slowly growing left subcutaneous paranasal and cheek mass lesions
Fullness of the left side of the nose on exam and was soft and mobile with an irregular shape
Clinical plan was to perform imaging for resection of mass

5. Postcontrast Coronal T1 Weighted Fat Suppressed Images
Noninvasive soft tissue thickening and mass-like lesion, following the signal intensity of muscle
Mild enhancement of the lesion, similar to the degree of enhancement of other muscles
Lesion follows the anatomy of multiple perioral and facial muscles
No extension beyond the contour of these enlarged muscles

6. Postcontrast Axial T1-weighted Fat Suppressed Images
Mild enhancement of the lesion, similar to the degree of enhancement of other muscles

7. Axial T1-weighted Images
Noninvasive soft tissue thickening and mass-like lesion along the nasolabial region, following the signal intensity of muscle

8. CT and MRI Imaging Findings
Noninvasive soft tissue thickening and mass-like lesion along the nasolabial region, following the signal intensity of muscle on T1- and T2-weighted images
Mild enhancement of the lesion, similar to the degree of enhancement of other muscles
Compatible with the prior pathology of striated muscle and fat
Lesion followed the anatomy of multiple perioral and facial muscles
Orbicularis oris, Zygomaticus, Risorius, Levator anguli oris, Levator labii superioris, Nasalis, Procerus, and parts of the Orbicularis oculi muscles
No extension beyond the contour of these enlarged muscles
Based on these features and prior pathology, diagnosis of Hemifacial myohyperplasia was made

9. Hemifacial Myohyperplasia
Very rare and relatively recently described – very few cases reported in literature
Congenital and/or progressive hyperplasia of some or all of the muscles of the facial and masticator muscles on one side
Generally, no evidence of hyperplasia in other areas of the face or other organ systems
Challenging diagnosis
May mimic neoplastic or infectious conditions
May potentially lead to unnecessary treatments

10. Summary
Hemifacial myohyperplasia is a rare and intriguing disorder of the facial muscles in children that can present diagnostic challenges
Clinical and imaging features of hemifacial myohyperplasia may mimic head and neck neoplastic or infectious etiologies in pediatric patents and may potentially lead to unnecessary treatments
The patient presented depicts the distinctive radiologic findings with reported normal muscle pathology report, which can characterize this rare disorder.

11. References
Pereira-Perdomo, D. F., Velez-Forero, J., Prada-Madrid, R. Hemifacial myohyperplasia sequence. Am. J. Med. Genet. 152A: , 2010.
Castillo Taucher S, Pardo Vargas RA, Caivi Len D. Hemifacial myohyperplasia: an additional case. Am Med Genet A Jan 1; 116A (1):103-4.
Lee, S., Sze, R., Murakami, C., Gruss, J., Cunningham, M. Hemifacial myohyperplasia: description of a new syndrome. Am. J. Med. Genet. 103: , 2001.
Staffenberg, D. A., McCarthy, J. G., Hollier, L. H., Grayson, B. H., Verdi, G. Hypertrophy and asymmetry of the facial muscles: a previously unrecognized association. Ann. Plast. Surg. 40: , 1998.

12. Thank you