Posterior quadrantic dysplasia with localized hemimegalencephaly in a patient with giant congenital melanocytic nevus: First case report

Abstract

Giant congenital melanocytic nevus (GCMN) is associated with neurocutaneous melanocytosis and various other neurological complications. Its association with migrational anomalies of the brain is extremely rare. Herein, we document the first case of GCMN in a one-day-old baby associated with localized hemimegalencephaly (HME) of the brain with extensive malformation of cortical development including polymicrogyria, pachygyria and sublobar dysplasia, limited to an enlarged quadrant of the brain. HME and GCMN are considered embryological anomalies of cell migration and proliferation. We discuss the unusual magnetic resonance imaging findings along with a brief review of the literature. To the best of our knowledge, our case is the first to report the association of GCMN with localized HME.

Hemi-Hemimegalencephaly or Posterior Quadrantic Dysplasia, a Rare Cause of Focal Epilepsy in an Otherwise Healthy Young Woman: A Case Report

“…Hemimegalencephaly (HME) is a rare congenital malformation of cortical development (MCD) characterized by enlarged and dysplastic hamartomatous overgrowth of one or all parts of a cerebral hemisphere [1,2]. HME may be present in isolation or conjunction with other neurocutaneous syndromes such as epidermal nevus, Klippel-Trénauany-Weber syndrome, neurofibromatosis type 1, hypomelanosis of Ito, Proteus syndrome, or more rarely, tuberous sclerosis [3,4]. The MRIs of patients with HME reveal moderate-to-marked enlargement of an entire or a part of a cerebral hemisphere with the normal, dysplastic, or heterotopic cortex.…”

“…Other clinical manifestations could be early feeding problems, infantile spasm, macrocephalus, hydrocephalus, and mild hemiparesis [ 2 ]. Most commonly, HME affects an entire hemisphere, but localized forms have also been reported in the literature, with the most notable being posterior quadrantic dysplasia (PQD) or hemi-HME with an enlargement of the parieto-occipito-temporal lobe, sparing the frontal lobe of a single hemisphere [ 4 , 8 - 11 ]. Dysmorphic ipsilateral occipital horn with high-signal posterior periventricular white matter and abnormal gyri can be observed in most patients with PQD [ 2 , 8 ].…”