A consistent pattern of craniosynostosis in the sagittal and bilateral lambdoid 
sutures is described in three patients. The external cranial ridging associated 
with fusion of these sutures produces a characteristic triradiate, or "Mercedes 
Benz," appearance to the posterior skull. Locally marked growth restriction is 
evident in the posterior fossa with compensatory secondary expansion of the 
anterior fossa manifesting a degree of frontal bossing which mimics bicoronal 
synostosis. Although this appearance could lead to inadvertent surgery in the 
frontal region, attention to the occipital region with wide early suture 
excision and vault shaping is indicated.