Porokeratotic palmoplantar keratoderma discreta--a new entity or a variant of porokeratosis plantaris discreta?

We report a family with hyperkeratotic lesions on palms and soles. The lesions became evident in the second to third decade, and there is an autosomal dominant mode of transmission. Skin biopsy specimens show a central epidermal depression filled by a compact hyperkeratotic plug of columnar parakeratosis, like a broad cornoid lamella. The lesions resemble porokeratosis plantaris discreta clinically and histologically. The cornoid lamella is a broad, solid keratin plug rather than a centrifugally enlarging annular or serpentine ridge as can been seen in other types of porokeratosis. Perhaps the lesions of porokeratosis plantaris discreta should not be classified as a true porokeratosis but as porokeratotic plantar keratoderma discreta. We have therefore called the lesions in our patients porokeratotic palmoplantar keratoderma discreta, and suggest that porokeratotic palmoplantar keratoderma discreta is a variant of porokeratosis plantaris discreta.