Abstracts

Rationale: Heide's syndrome is a distinct entity characterized by a triad of congenital hemifacial hyperplasia with lipomatosis (CHHL) AKA CILF, facial epidermal nevus (keratinocytic or sebaceous) and ipsilateral hemimegalencephaly (HME). Principal neurological manifestations are epilepsy and cognitive deficits. Recently it was discovered that CHHL is due to somatic mutations in PIK3CA. The first patient with hemimegalencephaly confirmed by autopsy in 1955 was Heide, a 7-year-old German girl with epilepsy (infantile spasms) and intellectual deficit. She was a victim of "active euthanasia" in 1944. Heide's syndrome was delineated in 2012-2013. Many reports in the literature have focused in one of the three components. Methods: Review of 27 patients of Heide's syndrome from personal experience and the literature published under numerous terms including cranial hemihypertrophy, facial hemihypertrophy, etc. since 1863. Results: HME was confirmed in all cases with neuroimaging studies, CHHL present in all, ipsilateral facial nevus (keratinocytic or sebaceous) in 26 cases; except for one case, all had epilepsy; the most frequent type was infantile spasms. Conclusions: Heide's syndrome is an under-recognised entity, recently delineated as a neurological phenotype of ENS that also can be included in the PIK3CA-related overgrowth spectrum. Heide's eponym is justified medically, historically and ethically, not only because Heide was the first patient described, but also to enhance identification of other patients. Congenital hemifacial hyperplasia with lipomatosis (CHHL) is a distinctive mosaic overgrowth disorder involving several ENS phenotypes. Oncogenic PIK3CA mutations are related to CHHL, HME and keratinocytic epidermal nevus syndrome explaining their common association. Heide's syndrome can be diagnosed prenatally by imaging. Funding: None