Identification of Hypomelanosis of Ito in Pediatric Primary Care

Neurocutaneous disorders identified in the neonatal period and infancy: Hypomelanosis of Ito

Hypomelanosis of Ito is a rare neurocutaneous disorder named after the Japanese dermatologist Minoru Ito who in 1952 described the condition. Characteristically, the hypopigmented lesions in this condition follow Blaschko lines. Extracutaneous manifestations of the disease include neurological, musculoskeletal, cardiac, endocrine, and renal signs and symptoms. The most common neurological manifestation is cognitive impairment. Seizures, developmental delay, and abnormal tone can also be present. In this review we discuss the condition's clinical presentations, its diagnostic criteria, and consensus recommendations.

Monogenic causes of pigmentary mosaicism

Pigmentary mosaicism of the Ito type, also known as hypomelanosis of Ito, is a neurocutaneous syndrome considered to be predominantly caused by somatic chromosomal mosaicism. However, a few monogenic causes of pigmentary mosaicism have been recently reported. Eleven unrelated individuals with pigmentary mosaicism (mostly hypopigmented skin) were recruited for this study. Skin punch biopsies of the probands and trio-based blood samples (from probands and both biological parents) were collected, and genomic DNA was extracted and analyzed by exome sequencing. In all patients, plausible monogenic causes were detected with somatic and germline variants identified in five and six patients, respectively. Among the somatic variants, four patients had MTOR variant (36%) and another had an RHOA variant. De novo germline variants in USP9X, TFE3, and KCNQ5 were detected in two, one, and one patients, respectively. A maternally inherited PHF6 variant was detected in one patient with hyperpigmented skin. Compound heterozygous GTF3C5 variants were highlighted as strong candidates in the remaining patient. Exome sequencing, using patients' blood and skin samples is highly recommended as the first choice for detecting causative genetic variants of pigmentary mosaicism.

The Rare Neurocutaneous Disorders: Update on Clinical, Molecular, and Neuroimaging Features

Phakomatoses, also known as neurocutaneous disorders, comprise a vast number of entities that predominantly affect structures originated from the ectoderm such as the central nervous system and the skin, but also the mesoderm, particularly the vascular system. Extensive literature exists about the most common phakomatoses, namely neurofibromatosis, tuberous sclerosis, von Hippel-Lindau and Sturge-Weber syndrome. However, recent developments in the understanding of the molecular underpinnings of less common phakomatoses have sparked interest in these disorders. In this article, we review the clinical features, current pathogenesis, and modern neuroimaging findings of melanophakomatoses, vascular phakomatoses, and other rare neurocutaneous syndromes that may also include tissue overgrowth or neoplastic predisposition.

Possible Correlation between Hypomelanosis of Ito and Wilms’ Tumor

Hypomelanosis of Ito is a neurocutaneous disorder characterized by skin manifestations in a characteristic pattern associated with musculoskeletal and central nervous system symptoms. Our patient was diagnosed with Wilms' tumor stage I at age two and was also found to have distinct streaked areas of skin hyper- and hypopigmentation suggestive of Hypomelanosis of Ito. We believe that our patient's clinical diagnoses of Hypomelanosis of Ito and Wilms' tumor are interlinked. The connecting factor is yet to be identified. Our patient does not have a deletion of 11p13 associated with a defect in WT1, the Wilms' tumor suppressor gene. As such, it is quite possible that what made her more susceptible to the development of Wilms' tumor was her Hypomelanosis of Ito, which is implicated in a number of other organ dysfunctions.