How is psoriasis to be distinguished from squamous eczema?
By the sharply-defined, circumscribed, scattered, scaly patches, and by the history and course of the individual lesions.
In what respects does the papulo-squamous syphiloderm differ from psoriasis?
The scales of the squamous syphilide are usually dirty gray in color and more or less scanty; the patches are coppery in hue, and usually several or more characteristic scaleless, infiltrated papules are to be found. The face, palms, and soles are often the seat of the syphilitic eruption; and, moreover, concomitant symptoms of syphilis, such as sore throat, mucous patches, glandular enlargement, rheumatic pains, falling out of the hair, together with the history of the initial lesion, are one, several, or all usually present.
How does seborrhœa differ from psoriasis?
Seborrhœa of the scalp is usually diffused, with but little redness and no infiltration; moreover, the scales of seborrhœa are greasy, dirty gray or brownish, while those of psoriasis are dry and commonly whitish or mother-of-pearl colored. Psoriasis of the scalp rarely exists independently of other patches elsewhere on the general surface.
That variety of seborrhœa, commonly known as eczema seborrhoicum, presents at times, both on scalp and general surface, a strong resemblance to psoriasis, but the character of the scales and distribution of psoriasis, as above stated, are distinguishing points; seborrhœa, moreover, favors hairy surfaces and in extensive examples the scalp, eyebrows, sternal, and pubic regions rarely escape.
How does psoriasis differ from ringworm?
By its greater scaliness, by its higher degree of inflammatory action, and by its larger number of patches, as also by its history. In ringworm all the patches tend to clear up in the centre; in psoriasis this is rarely, if ever, so. If there is still any doubt, microscopic examination of the scrapings will determine.
Give the prognosis of psoriasis.