General Remarks.
There are two important disease of the skin with which we shall deal in this chapter-namely, pityriasis and psoriasis. In the former malady, in its typical form, the surface of the body is deeply reddened (hyperaemic), and covered by large and freely imbricated scales or flakes; hence the term applied to it- pityriasis rubra. In the disease there is no real inflammation in the form of new products. Hebra allies it to eczema, and upon the ground that “we occasionally find moist excoriated patches on other portions of the skin, especially in the flexures of the joints.” But this is infinitely rare; from beginning to end, there need be nothing but hyperaemia and scaliness present in the disease.
There is not necessarily any change in the corium tissue or the connective tissue, though the hyperaemia, if persistent, may be followed by hyperplasia and thickening of these parts, but only as accidental epiphenomena.
In psoriasis a somewhat different state of things obtains; there is hyperaemia of the papillary layer of the skin, with hyperplasia of the epithelial elements, but I believe the latter to be the more important of the two; and in this respect psoriasis contrasts with pityriasis rubra-the former psoriasis contrasts with pityriasis rubra-the former being essentially a disease of cell tissue, the later rather an hyperaemia, primarily.
Pityriasis Rubra.
Under this title two distinct types of diseases have been described- the one by Devergie and the other by Hebra. They both possess certain marked features which would entitle them to the designations they have received; but, as there are also marked differences in their course, and prognosis, they must and should receive separate consideration.
Pityriasis Rubra (Devergie).
This affection is chiefly met with in persons between the ages of forty and fifty, and commences by the appearance of well- marked redness, with a sharply limited margin on the anterior aspect of the trunk and limbs. As it advances new surfaces are invaded, the skin slightly thickens, and the increase may be so rapid that the entire skin may become involved in from two to four weeks. Accompanying this diffuse redness we find free desquamation of exfoliation of medium-sized epidermic scales, with more or less watery exudation, resembling sweat rather than the lymphy and plastic exudation of eczema. There is also an intense burning heat of the surface, so that the patient suffers from the warmth of his clothing and of the bed coverings at night.
The acute symptoms mentioned are tenacious, and the affection may persist in this condition for months, but in perhaps the majority of cases they gradually subside, and recovery takes place.
On the other hand, the acute phase of the disease may be followed by one that is subacute, but more persistent, and continue to harass the patient for years, gradually breaking down his health and terminating fatally, through the supervention of chronic diarrhoea or the development of pemphigus.
The prognosis is in the main favorable, except when it occurs in aged or debilitated subjects, or assumes the distinctly chronic form.
Pityriasis Rubra (Hebra).
Under this name Hebra has described a disease that is wholly different from the foregoing, and the principal characters of which are as follows:
The skin presents a persistent deep-red coloration, distributed over the entire surface, but without papules, vesicles, or any exudation. Scales are found in small numbers, but do not become a prominent feature of the affection.
The local subjective symptoms are insignificant.
The progress of the disease is remarkably slow, and in its early periods the general health is not notably affected; but little by little there is a gradual weakening of the vital forces, and fatal marasmus marks the termination of the patient’s sufferings.
It will be seen from the foregoing that the affections described under the same name by the eminent French and German authors differ from each other in every important respect, and are, in fact, quite distinct diseases.
Dr. Piffard has met with a number of cases of Devergie’s disease, but only a single undoubted example of the malady described by Hebra.
If, as asserted by Hebra, pityriasis rubra is always and unnecessarily fatal, treatment other than palliative is out of the question.
In Devergie’s affection, however, every effort should be made to cut short its progress, and benefit may be expected from baths, emollients, and therapeutics.
Soothing local applications, such as bran baths or a decoction of walnut leaves followed by oily inunctions, and later by oil of white birch, are important aids. Lotions corrosive sublimate 1-1000, or with hydrate of chloral 1-50 or 1-100, constitute an excellent application in pityriasis capitis. Sulphurated pomades have been advised; flowers of sulphur 1-30 or 1-60. For pityriasis of the face a pomade of calomel 1-100 is often efficient.
Arsenicum album is the principal internal remedy used by both schools. It produces pityriasis by its physiological action; its well known characteristics indicate its use; feverishness, with restlessness and thirst, for small quantities, etc.
Natrum arsenicum.-This drug corresponds very closely to the leading peculiarities of this disease, and I have prescribed it successfully in several cases. Its skin symptoms read: “Squamous eruption, scales, thin, white, and when removed leave the skin slightly reddened. If scales remain they cause itching, worse when warm from exercise.”
Arsen. iod. and Kali ars. are preparations that may be occasionally useful. I have had no trustworthy experience with either.
Other remedies may be indicated as follows:
Antimonium crud.-Brownish-red spots, like small hepatic spots, here and there.
Cantharis.-Itching, followed by burning, when scratching; tendency to formation of blisters; most suitable when the disease appears in children.
Cocculus.-Red, irregularly shaped spots on the skin, over the whole chest, and on the sides of the neck, behind the ears, without heat or itching, intolerance of both cold and warm air.
Conium.-Frequently recurring red, somewhat itching, spots on the body.
Graphites.-Pityriasis capitis, dryness of the skin, with cracking; localization of the eruption; tendency to cold from draughts of air; pains from changes of the weather; abundant desquamation from the hairy scalp.
Kreasotum.-Uneasiness during rest, with irritation, through out the body; child cannot sleep unless carried or fondled; scaly ulceration on face, elbows, wrists and fingers.
Lachesis.-Small reddish spots on face, neck and chest, which increase in numbers, become scurfy, and then disappear.
Ledum.-Aching, bruised feeling in the whole body; warm sweat of the hands and feet; bluish spots on the body like petechiae; eruption itching, with anxiety; coldness is affected parts.
Mezereum.-Chronic pityriasis capitis, loss of hair and great itching, brownish miliary rash on the chest, arms and thighs; phlegmatic temperament, with light hair.
Phosphorus.-Brown, bluish-red, or yellow blotches on abdomen and chest.
Sepia.-Brown-red hepatic spots on the skin.
Sulphur is advised by the two schools. Its pathogenesis contains the formation of furfur.
Tartar emet.-Eruption dependent upon gastric derangement, nausea and vomiting, with thick white coating on tongue.
Pityriasis Pilaris.
Devergie, who was the first to describe this rare dermatosis, states that in its most benign form it consists of a more or less localized eruption on the external aspects of the members, and especially the forearms and legs. The essential seat of the eruption is at the pilous orifices of the general surface, but not on the scalp. The only lesion is a minute papule, with a small adhering scale.
In more severe cases it may become generalized, with slight thickening of the skin about the follicle, forming a small, red pyramidal papule decked with a white scale. The skin between the papules is apparently unchanged.
There is little or no pruritus, and it apparently causes but trifling inconvenience to the patient,, except as it progresses from bad to worse.
It is exceedingly obstinate, and palliative and emollient treatment is our only resource.
When associated, as it may be, with pityriasis rubra, it presents a striking likeness to lichen, rubra and may possibly be in reality the same affection.
There is considerable discussion as to whether pityriasis is not a parasitic affection. Some observers claim to have discovered a special parasite in this affection, consisting a very minute spores, averaging a thousandth of a millimetre in diameter. The extreme smallness of the spores and their irregularity in size have induced M. Vidal to name the parasite Microsporon anomoeon or dispar.
This is a point that has not been fully settled as yet, and I prefer to class the disease among the squamous inflammations until further light has been thrown upon the subject.
Sepia and Natr. ars. are the principal internal remedies for pityriasis pilaris.
Psoriasis.
Psoriasis is a constitutional disease, characterized by cutaneous lesions of the squamous type.
