Most cases of ichthyosis are congenital in origin. A hereditary tendency has been noted repeatedly. Gray1 postulates that the horny overgrowth is an attempt to compensate for the protection usually supplied by the oily secretions.
Acquired ichthyosis is rare but cases do undoubtedly occur. Such were described by Crocker,2 who also mentioned the ichthyosis which is liable to afflict the Piper methysticum chewers of the Sandwich Islands. Little additional information is given by the Suttons,3 who quote from Crocker.
Trophic changes, consisting of dryness of the skin, atrophy, hyperkeratosis and alopecia, are seen not infrequently in Hodgkin's disease. Ronchese4 has described such a case. An ichthyosiform atrophy of the skin developed in a patient with lymphadenoma while he was in apparently good health, eleven months before his death. The changes took only six weeks to mature and were widespread. The cutaneous surface became rhomboidal scales with