Milia May Originate from the Outermost Layers of the Hair Bulge of the Outer Root Sheath: A Case Report

The study conducted in 2016 aimed to identify the origin of milia, a type of skin condition, using immunohistochemical methods. The researchers used anti-keratin and anti-filaggrin antibodies to determine the levels of keratin and filaggrin expression. The study found that K1 and K10 keratin expression were detected in the more superficial sections of the cyst walls, while K14 and K17 were expressed in all layers of the cyst walls. Notably, K15 was expressed in the outermost layer of the deeper section of the cyst walls and hair germ structure. Filaggrin was expressed in the superficial layer of the more superficial section of the cyst walls. The pattern of keratin and filaggrin expression suggested that milia may originate from the outermost cells of the hair bulge of the outer root sheath. However, further studies were recommended to confirm this hypothesis.