TCF12-related bicoronal craniosynostosis complicated by a large middle fossa arachnoid cyst and developmental regression: a case report.

Pathogenic variants in Transcription Factor 12 (TCF12) have been identified as genetic causes of craniosynostosis. The phenotypic spectrum of TCF12-related craniosynostosis is broad and remains incompletely understood. Herein, we report a case of a 2-month old male with a heterozygous pathogenic variant of TCF12 (c.1267C > T; pArg423*) and bicoronal craniosynostosis. He underwent bicoronal suturectomy at 4 months of age, followed by post-operative molding helmet therapy. He returned at 2 years of age with developmental regression including loss of expressive language and fine motor skills. Shortly after he developed clinical findings of elevated intracranial pressure (ICP) and was found to have synostosis of the sagittal and bilateral lambdoid sutures, and a Galassi III left middle fossa arachnoid cyst with significant midline shift, requiring surgical fenestration. Post-operatively, the cyst decreased in size with resolution of midline shift. The patient did not regain any developmental milestones and continued to demonstrate deficits in language, social communication, and fine motor function despite resolution of other preoperative signs and symptoms of elevated ICP. To our knowledge, this is the first reported case of TCF12-associated craniosynostosis with a co-occurring arachnoid cyst. Furthermore, there is limited literature describing the long-term neurodevelopmental outcomes of children with TCF12 pathogenic variants. Thus, this case offers expanded insight into the broad phenotypic spectrum of TCF-12 related craniosynostosis and its potential clinical sequelae.