Darier's disease is comparatively rare. Darier's disease with malignant transformation is extremely rare. Only one case of such degeneration is reported in the literature, that of Wende, recorded in 1908.1 The disease was first described by Morrow, in 18862 as one of keratosis follicularis. The second case was reported under the same name by White in June 1889.3 A month later, in July 1889, Darier4 reported the third case and described a parasite of the order of Sporozoa, the so-called psorosperms, which he observed in the epidermis and which he regarded as the causative factor of this disease. When White5 observed a fourth case of keratosis follicularis a year later he referred to the disorder in a subheading as psorospermose folliculaire végétante. However, in the text he mentioned the uncertainty of the existence of the organism, a doubt as to