ICHTHYOSIS. 



445 



of the disease, which remains confined to portions only of the skin, 

 and which complicates pachydermy. 



SYMPTOMS AND COURSE. Instead of presenting the smooth ap- 

 pearance usually seen upon the skin of a healthy person, the skin in 

 the milder grades of ichthyosis is roughened and covered with delicate 

 white scales. It is this milder form of the disease which is usually 

 called pityriasis. The term pityriasis, in this sense, signifies a des- 

 quamation of the cuticle depending upon a mere exuberant growth of 

 epidermis, and not upon other disease. We know such to be the case, 

 from the habitual presence of the conditions above described, and by 

 the absence of any symptoms of congestion or of inflammation, or of 

 any derangement in the secretion of the glands and sebaceous follicles. 

 Most cases of desquamation of the epidermis upon the head, in which 

 the fine white scales adhere to the hair, and cover the collar of the coat, 

 do not depend upon exuberant formation of epidermis, but upon a 

 superficial dermatitis. The scaling off of the skin of the palms of the 

 hands and soles of the feet, too, is generally due to superficial inflam- 

 mation of the skin, and will be discussed more in detail in the chapter 

 upon eczema. In genuine ichthyosis, the epidermis is detached in the 

 form of larger and thicker scales, usually stained of a dark color by 

 pigment and dirt. In the worst forms of the disease the epidermis is 

 in horny plates, and even forms warty or spinous projections. Hence a 

 great number of subordinate varieties of ichthyosis have been recog- 

 nized, ichthyosis simplex, cornea, hystrix, etc., which, however, are not 

 varieties in kind, but merely in the degree of the disease. Certain 

 parts of the body, the face, the palms of the hands, the soles of the 

 feet, the armpits, and the bends of the knees and elbows, are not at- 

 tacked by the affection, while its favorite seat is upon the dorsal sur- 

 face of the extremities, especially upon that of the knees and elbows. 

 Hebra accounts for the fact that we cannot, at first, detect the ex- 

 istence of ichthyosis in newly-born children, upon the ground that a 

 child in the womb of its mother is in a continual warm bath, which 

 keeps the epidermis in a state of maceration. Moreover, owing to the 

 continual necessity for washing little children in their first year, the 

 scales of epidermis are not allowed to collect, and hence the disease 

 usually remains undetected. 



TREATMENT. This disease is incurable, as we know of no remedy 

 capable of producing involution of the hypertrophy of the papillary 

 layer of the skin. Our experience as to the uselessness of arsenic, anti- 

 mony, tar, and other external and internal medicines, is too ample to 

 warrant our making further trial of them. It is well to advise the 

 patient to take a warm bath daily, with or without the addition of an 

 alkali, and diligently to anoint his skin with some unctuous substance, 



