[Hyperkeratosis punctata of the palmar creases]

The authors have collected 6 cases (one personal case and 5 cases from the literature) of hyperkeratosis punctata of the palmar creases, an affection which seems to be a new type of keratosis punctata. It is characterized by the development of small horny plugs in small cup-like depressions which are electively and exclusively found in the palmar flexion creases of the fingers. Histological examination shows a plug-like hyperkeratosis penetrating, more or less deeply, the depressed, funnel-like Malpighi's mucous layer which sometimes consists of one layer of cells. This affection might be compared to Kyrle's disease (and the hyperkeratotic plugs of mechanical origin). The histological evidence of non-rupture of the dermis by the horny plugs may not be considered as a sufficient factor of differentiation: however, other clinical criteria differentiate these various affections. In the absence of a known etiology we must conclude that this type of keratosis punctata confined to the palmar creases is an autonomous disease.