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Neuroradiology Case of the Week

Case 176

Jerry Lee, MD, and P-L Westesson MD, PhD, DDS

Clinical Information: Patient is a two-year-old male with deformity of the face. Assess for ocular or bony malformations.

Radiographic Findings: 3D cranial reconstructions of the patient (Figs. 1B, 2B, 3B) in comparison to 3D cranial reconstruction of a normal 1 1/2 year old (Figs. 1A, 2A, 3A). The findings of the patient include disproportionately small facial bones (Figs. 1B, 2B , & 3B), bilateral hypoplasia of the zygomatic bone, downslanting of the superior orbit roofs (Figs. 1B & 2B), incomplete zygomatic arches, hypoplasia of the mandible and hypoplastic coronoid processes of the mandible (Fig. 3B).

Discussion: Treacher Collins Syndrome or Mandibulofacial Dysostosis (MFD) is an autosomal dominant syndrome linked to a mutation in chromosome 5.  It is found in approximately 1 per 50,000 live births.  It is a disorder involving the first and second branchial arches. 

Clinical Features: 

• Micrognathia (“bird face”); symmetric underdevelopment of mandible
• Antimongolid slant of palpebral fissures
• Flattening of cheeks
• Colobomas of the lateral third of the lower eyelid with or without those of the upper lid
• Absence or deficiency of medial eyelashes
• Ear tags between tragus and angle of mouth may occur

Imaging  Features:

• Mandibular hypoplasia; very short rami, bilateral antegonial notching, compensatory growth of anterior part
• Dental malocclusion
• Bilateral hypoplasia or agenesia of the malar bone
• Incomplete zygomatic arches
• Downward sloping orbital floors in line medially with a beak-like bony nasal contour
• Malformation of external and middle ear
• Disproportionately small facial bones
• Paranasal sinuses often small, may be absent
• Lacrimal duct atresia
• Narrow palate
• Cleft palate in about 1/3

References:

1. Larheim TA, Westesson PL. Maxillofacial Imaging. Berlin, Springer, 2006.
2. Som PM, Curtin HD. Head and Neck Imaging, 4th ed. St Louis, Mosby, 2003: 63-64, 562.