Abnormal head MRI in a neurologically normal boy with hypomelanosis of Ito

Cerebral White Matter Lesions and Dysmorphisms: Signs Suggestive of 6p25 Deletion Syndrome-Literature Review

Deletion of the region including chromosome 6p25 has been defined as a syndrome, with more than 68 reported cases. Individuals affected by the syndrome exhibit variable findings, including developmental delay and intellectual disability, cardiac anomalies, dysmorphic features, and-less commonly-skeletal and renal malformations. Ocular and hearing abnormalities are the most notable presenting features. The region encompasses more than 15 genes, of which the FOX group is the most likely causal factor of the clinical manifestations. We report the case of a 2-year-old child with developmental delay, generalized hypotonia, facial dysmorphism, and anomalies involving malformations of the eyes, heart, teeth, and skeleton. The magnetic resonance imaging (MRI) of the child's brain displayed cerebral anomalies involving the white matter, perivascular spaces, and corpus callosum. Array-CGH (comparative genomic hybridization) analysis displayed a de novo partial deletion of the short arm of chromosome 6, extending 5.13 Mb from nt 407.231 to nt 5.541.179. In infancy, neuroradiologic findings of abnormalities in the cerebral white matter and other neurologic anomalies elsewhere in the brain, in association with dysmorphisms and malformations, are highly suggestive of the diagnosis of 6p25 deletion syndrome. When these anomalies are found, the syndrome must be included in the differential diagnosis of disorders affecting the cerebral white matter.

Macrocephaly: Solving the Diagnostic Dilemma

Macrocephaly is a relatively common clinical condition affecting up to 5% of the pediatric population. It is defined as an abnormally large head with an occipitofrontal circumference greater than 2 standard deviations above the mean for a given age and sex. Megalencephaly refers exclusively to brain overgrowth exceeding twice the standard deviation. Macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, whereas megalencephaly is more often syndromic. Megalencephaly can be divided into 2 subtypes: metabolic and developmental, caused by genetic defects in cellular metabolism and alterations in signaling pathways, respectively. Neuroimaging plays an important role in the evaluation of macrocephaly, especially in the metabolic subtype which may not be overtly apparent clinically. This article outlines the diverse etiologies of macrocephaly, delineates their clinical and radiographic features, and suggests a clinicoradiological algorithm for evaluation.

Characteristic brain magnetic resonance imaging pattern in patients with macrocephaly and PTEN mutations

We describe an MRI phenotype seen in a series of patients with mutations in PTEN who have clinical features consistent with PTEN hamartoma tumor syndrome (PHTS). Retrospective review of clinical data and MRI was performed in 23 subjects evaluated in four different tertiary care centers with clinical programs in inherited disorders of the white matter. Patients were referred due to abnormal MRI features and abnormal PTEN sequencing was identified. All subjects had significant macrocephaly (on average >4 SD above the mean), developmental delay with or without autism spectrum disorder and uniform MRI features of enlarged perivascular spaces and multifocal periventricular white matter abnormalities. The phenotype of PHTS may include MRI abnormalities such as multifocal periventricular white matter abnormalities and enlarged perivascular spaces. These neuroimaging findings, in association with macrocephaly and developmental delay, should prompt consideration of PTEN as a diagnostic possibility.

Hypomelanosis of Ito: clinical syndrome or just phenotype?

The term hypomelanosis of Ito is applied to individuals with skin hypopigmentation along the lines of Blaschko. Even though originally described as a purely cutaneous disease, subsequent reports have included a 33% to 94% association with multiple extracutaneous manifestations mostly of the central nervous and musculoskeletal systems leading to frequent characterization as a neurocutaneous disorder. A number of reports claimed familial occurrence and supported single gene inheritance for hypomelanosis of Ito, but none has been proved. Miscellaneous chromosomal mosaicisms have been demonstrated in some but not all affected individuals. Thus, it has been suggested that hypomelanosis of Ito is not a single condition but rather a nonspecific manifestation (ie, a phenotype) of chromosomal mosaicism and that this term should now be dropped. In this article, we review these developments focusing on the neurologic and genetic aspects of hypomelanosis of Ito. Our personal experience with 41 hypomelanosis of Ito patients and literature review led us to conclude that (1) the term hypomelanosis of Ito has been often misapplied to individuals with nonspecific "patchy depigmentation of the skin" who had several conditions of different etiologies; (2) the white matter involvement seen at neuroimaging in most of our hypomelanosis of Ito patients was similar to that reported in well-defined neurocutaneous disorders, including Sjögren-Larsson syndrome and incontinentia pigmenti; (3) whatever figures we take for associated central nervous system abnormalities in hypomelanosis of Ito, these represent the most frequent extracutaneous findings and, therefore, the use of the term neurocutaneous disorder for hypomelanosis of Ito might well be appropriate.

Hypomelanosis of ITO. A study of 76 infantile cases

We show the complications observed in a large series of children with hypomelanosis of Ito (HI) or incontinentia pigmenti achromians, studied in a neurology service over 30 years. Of the 76 patients, 35 were male (46%) and 41 female (54%) with ages ranging from newborn to 10 years at the time of the first visit. They were thoroughly studied from the clinical, genetic, psychological, neuroradiological, with computed tomography (CT) and/or magnetic resonance imaging (MRI), and electroencephalographic (EEG) points of view. Mental retardation was observed in 43 cases (57%) of whom eight (10%) showed autistic behavior; 16 (21%) were borderline and only 17 (22%) had a normal mental level (IQ > 85). Thirty-seven patients (49%) had seizures, consisting of infantile spasms in six cases (8%). Twelve cases showed macrocephaly and coarse facies, six had microcephaly, and 14 showed hypotonia with pes valgus and genu valgus. Three cases of cerebellar hypoplasia, another of intracranial arteriovenous malformation and another of distal spinal muscular atrophy were observed as well. Some other anomalies, such as syndactyly, clinodactyly, abnormalities of the skeleton, asymmetry of the facies, ears, body and/or extremities, gynecomastia and asymmetrical breasts, short stature, oral alterations, congenital cardiopathies and genital anomalies, were also occasionally found. Three children died, but necropsy was performed only in one. Anatomical and histological studies did not disclose specific findings.