Neuroradiology Case of the Week

Case 14

Lawrence Buadu, MD, PhD and P-L Westesson, MD, PhD, DDS

Clinical Presentation: Two siblings presented with mild congenital facial anomalies. They appear to have a small mid-face and relatively flat zygoma regions. One of the siblings has a slightly small mandible but was otherwise normal.

Radiographic Findings: Three-dimensional CT scans demonstrates bilateral absence of the zygomatic arch in both siblings (Figs. 1 & 2). The muscles of mastications were present without anomalies or hyperplasia. In one of the siblings (Fig. 3) the mandible was slightly small but the mandibular condyles were developed on both sides in both siblings.

Figure 1A	Figure 1B
Figure 1A&B: Lateral views of three-dimensional CT scan of the head show absence of zygomatic arch bilaterally (arrows) in sibling #1.
Figure 2A	Figure 2B
Figure 2A&B: Lateral views of three-dimensional CT scan of head show absence of zygomatic arch bilaterally (arrows) in sibling #2.
Figure 3A	Figure 3B
Figure 3A&B: Bilateral relatively well-formed temporomandibular joints in sibling #1.

Diagnosis: Bilateral absence of zygomatic arch in two siblings

Discussion: Bilateral absence of zygomatic arches in two siblings has not been described previously. Single patients with cleidocranial dysostosis have been described in two families from an Italian article [1]. Zygomatic arch absence has also been described in a single case as a new feature of the so-called “ablepharon macrostomia syndrome” [2].

References:

1. Pastremoli A, Cantoni E, Graziani E, Manzoli L, Mosca S. Anatomico-clinical features of malar bone hypoplasia in cleidocranial dysostosis. 2 familial cases with interruption of the zygomatic arch. (Italian) Minerva Stomatologica. June 1986. 35(6):575-582.
2. Jackson IT, Shaw KE, del Pinal Matorras F. A new features of the ablepharon macrostomia syndrome: zygomatic arch absence. Review. British Journal of Plastic Surgery. July 1988. 41(4):410-416.