Spiny Keratoderma: A Demonstration of Hair Keratin and Hair Type Keratinization

The study analyzed six cases of spiny keratoderma using hair-specific antikeratin antibodies and electron microscopy, revealing that the keratotic column showed different keratin birefringence and less eosinophilic viable epidermis compared to surrounding skin. AE13, specific for hair cortex, was positive in the lower column and sometimes in the viable epidermis beyond the lesion, while AE14 was negative. Electron microscopy showed keratinization similar to normal hair cortex, with keratin filaments forming without keratohyalin or trichohyalin granules, and no cementsomes or marginal bands. The findings suggested that spiny keratoderma might represent ectopic hair formation on palms and soles.