Hair collar sign BY: MOHAMMED ALSAIDAN

Hair collar sign Ring-like hypertrichosis consisting of coarser and longer hair surrounding a congenital alopecic lesion on the midline of the scalp. A marker of cranial dysraphism, including encephaloceles, meningoceles, Cutaneous meningothelial tumors (heterotropic brain tissue), dermoid cyst , aplasia cutis congenita, Dandy Walker malformation or agenesis of the corpus callosum Due to neuroectodermal abnormalities in embryonic development of the cranial neural tube resulting in down-regulation of pathogenic antibodies production . Fc Fc (Fragment, crystallizable) region Fab antigen binding

Hair collar sign Encephaloceles and meningoceles communicate directly to the central nervous system by herniation of intracranial structures through a scalp defect Heterotropic brain tissue is found with an intact cranium and no connection to the brain complex interaction between epithelium and mesenchyma nerve tissue stimulates hair growth greater density of hair could be explained by the displacement of follicles at the lesion’s border

Associations Port wine stain Subcutaneous hemangioma the presence of a vascular malformation with a second cutaneous marker heightens the likelihood of dysraphism Cardiac defect ( e.g. VSD) Oculoectodermal syndrome : include epibulbar dermoids and other ocular abnormalities, skin hyperpigmentation, congenital heart defects, urinary tract malformations, and neoplasms Syndactyly , cleft lip and palate, sclerocornea, scalp epidermal nevus, lipodermoid also have been reported resulting in down-regulation of pathogenic antibodies production . Fc Fc (Fragment, crystallizable) region Fab antigen binding

Approach Present at birth ? Growing in size ? Bulging with crying ? Thorough physical examination with neurologic evaluation Brain MRI Screening for spinal abnormalities (spine, spinal cord) Genetic counseling ? Translocation t(1;4) (q44;q10). Abdominal ultrasound, metabolic screening resulting in down-regulation of pathogenic antibodies production . Fc Fc (Fragment, crystallizable) region Fab antigen binding