Unlike other verrucae, mosaic warts are found only on areas of the body devoid of hair. Clinicians usually discuss mosaic warts1 in the differential diagnosis of plantar warts. Their occurrence on other nonhairy portions of the skin has been overlooked. The differential diagnosis of hyperkeratotic lesions of the palms (Fig. 1), periungual areas (Fig. 2), knuckles (Fig. 3), and other nonhairy sites (Fig. 4) must include mosaic warts. Paring will reveal the individual cores of the mosaic pattern and establish the proper diagnosis.
Of all types of warts, periungual mosaic warts are the most difficult to eradicate. In many cases they are associated with mosaic warts of the soles and have probably been spread to the fingers through picking the plantar lesions.
Royal M. Montgomery, M.D., 57 West 57th St., New York 19.