Age of onset is usually between 6 and 20 years,
with peak onset around puberty. Keratotic papules appear predominantly on
the upper trunk and may involve the face, scalp, neck, hands (palms), feet
(soles), and limb flexures (axillae, groins). The papillomatous masses may
become malodorous. Nail dystrophy manifests as subungual hyperkeratosis,
fragility, longitudinal ridging and splitting, and longitudinal red and
white lines. Mucous membranes, such as lips, buccal mucosa, hard palate,
alveolar ridges, uvula, pharynx, larynx, and vulva, are rarely involved.
However, if involved, papules, fissures, crusts, and ulcers may result.
Secondary cutaneous infection (herpes virus, bacterial) is a frequent
complication. The disease is exacerbated by sunlight or sunburn.
Occasionally, patients suffer from a seizure disorder and mild mental