B, Koilocytes containing enlarged, irregular, and hyperchromatic nuclei, perinuclear halos, and coarse keratohyalin granules
are found in the granular and upper spinous layers.
Among the components of keratohyalin granules
, FLG has a crucial role in maintaining normal epidermal barrier function.
Histopathologically, the papillomas associated with juvenile papillomatosis have little or no surface keratinization, and they contain no keratohyalin granules
Similar to classic BD, pagetoid BD always shows full-level involvement of the epidermis, scattered multinucleated tumor giant cells, keratohyalin granules
, single-cell keratinization, and intercellular bridges visible between pagetoid cells, while EMPD lesion contains pagetoid cells well demarcated from nearby epidermal cells, flattened basal layer, stratum corneum involved, acinar structures, and no intercellular bridge.
In epidermis, moderate to severe acanthosis, mild to severe hyperkeratosis, hydropic degeneration of keratinocytes and many koilocytes with variably sized keratohyalin granules
In 2006, Irvine and McLean (7) studied the histology of normal and atopic skin and demonstrated that the skin in AD has a defective barrier, with an absence of filaggrin-containing keratohyalin granules
in the epidermal granular layer.