A Polarizing Light Microscopy Can Be an Easy and Reliable Diagnostic Tool of Congenital Keratinizing Disorders Including Netherton Syndrome

The study found that polarizing light microscopy could serve as an easy and reliable diagnostic tool for congenital keratinizing disorders, including Netherton syndrome (NS). NS is characterized by congenital ichthyosis, atopic manifestations, and trichorrhexis invaginata (TI), but TI detection can be challenging as it decreases with age. The researchers discovered a novel hair anomaly in NS patients, where the hair shaft showed a characteristic discontinuity of polarized light, which was more frequently and easily observed than TI. This band-like discontinuity ranged from 0.1mm to 1.0mm wide and was linked to irregular melanin distribution. Similar features were noted in other congenital keratinizing disorders, though they were distinct from NS. This finding suggested that polarizing light microscopy could effectively diagnose these disorders.