Hemimegalencephaly is a wide spectrum of central nervous system overgrowth syndromes manifesting with macrocephaly and varied cortical malformations. These processes predominantly occur through mTOR-PI3K-AKT and RAS-ERK-MAPK related pathways. PTEN, PIK3CA related overgrowth spectrum (PROS), NSD1,EZH2 and 11p15.5 are well known genetic mutations. Multisystem involvement with hypertrophy of cutaneous -connective soft tissues and cranio-spinal anomalies are noted. A couple of these mutations are also known to have tumor predisposition conditions. Bannayan–Riley–Ruvalcaba syndrome (BRRS) , Cowden syndrome, CLOVES, Sotos, Klippel-Trenaunay syndrome (KTS) , Proteus, Megalencephaly-Capillary malformation -Polymicrogyria (MCAP) and Megalencephaly-Polydactyly -Polymicrogyria -Hydrocephalus ( MPPH) and Beckwith-Wiedemann are well known entities.