Psoriasis is a very common skin condition characterized usually by silvery white scales, that leave a red base if they’re scraped off (see pictures below). It’s an auto-immune disease, often with genetic components, characterized by inflammation. It affects men and women equally, and seems to be more common in temperate climates as one moves away from the equator.
Psoriasis most commonly occurs on parts of the body that are taut when bent, such as the back of the elbows, the front of the knees, the backs of the ankles (Achilles tendon), and the sacrum at the bottom of our low back, and tailbone (coccyx). These are called “extensor surfaces” in medical-speak (where muscles & tendons stretch to straighten a joint).
When Psoriasis occurs at the hairline, and creeps backward in the scalp, it can cause hair loss. Guttate Psoriasis consists of small round circular plaques of the scale (“guttate” means “drop-like”); this can be quite extensive. Pustular psoriasis can also be extensive, with its boil-like lesions, and can even cause fever or liver / kidney damage; it tends to only happen among persons who get outside infections, are pregnant, or take & then cease to take steroids.
Most Psoriasis is limited to small areas of the body. But some people have widespread involvement, which is very distressing. Psoriasis has been termed a “heartache.”
The Koebner Phenomenon is when psoriasis develops from a skin wound. In persons with psoriasis, the entire skin is affected; most of it never develops lesions, though skin trauma can precipitate new areas. When nails are involved, they may develop tiny pits. This happens mostly in persons with Psoriatic Arthritis, which is not a complication, but rather its own separate condition. “Inverse Psoriasis” occurs where it shouldn’t, i.e. in folds where skin touches skin, like the groin, the armpits, under the breasts, or between the buttocks. In those areas, we may see shiny streaks without plaques, leading us to think of fungal or bacterial infections instead.
Nothing can “cure” psoriasis, but many treatments can control it. The main one are prescription steroid creams, which are much more potent than over-the-counter hydrocortisone. Extensive involvement all over the body is not so amenable to applying topical medication. Dermatologists can prescribe “phototherapy,” in booths with ultraviolet light (in doses more controlled & systematic than tanning salons). Unfortunately, simply telling patients to “get more sun exposure” rarely helps.
Newer oral and systemic medications work quite well, and are heavily advertised on TV. But since they work against the immune system, they carry a risk of predisposing to infections, which may be life-threatening. Despite the drug company’s promise of “clear skin,” we shouldn’t use them for patients whose psoriasis is limited to small-enough areas which can be treated with creams or ointments.
Some Pictures of Psoriasis:
Psoriasis on the Scalp