(LifeWire) - Inverse psoriasis might be thought of as hidden psoriasis. This uncommon condition presents a similar rash to standard psoriasis, but it doesn't appear on exposed areas of the body. Instead, it occurs in the skin folds, such as the armpit and groin, and it can produce debilitating pain and itching.
Inverse psoriasis appears as a red rash that's tender, though it lacks the scales of standard psoriasis. The itching and soreness are particularly troublesome because it only presents itself in the "flexure" areas of the body. These areas include the groin, armpits, under the breasts, in folds around the genitals and under the buttocks. For some, the painful rash can be found in deep skin folds along the waist, stomach and thighs.
Perspiration and friction, difficult to avoid in the flexure areas, only make the condition worse.
Experts say anyone with severe irritation and redness in the genital area could have inverse psoriasis, even if they have never been diagnosed with psoriasis. The psoriasis on another part of the body could be very mild, even passed off as simple dandruff.
The condition, which usually occurs in about 2% to 6% of those with psoriasis, is more bothersome and more typical in people who are overweight. The connection between obesity and psoriasis has not yet been fully determined. However, research suggests that while extra pounds don't seem to influence the onset of psoriasis, extra weight can increase the severity of the condition.
Choose Treatment Carefully
Because inverse psoriasis occurs in some of the most sensitive areas of the body, treatment can be a challenge.
Topical medications used to treat inverse psoriasis range from over-the-counter hydrocortisone to prescription-strength medications, like Protopic (tacrolimus) and Elidel (pimecrolimus). According to an article published in 2007 in Dermatology, Protopic and Elidel are preferred over cortisone-type treatments in the flexure areas because of the skin sensitivity. Steroidal treatments, such as hydrocortisone, can cause skin thinning and other side effects.
However, the FDA recommends that Protopic and Elidel only be used as a last resort and only for a short period of time. The agency ordered the manufacturer to include a boxed warning for these treatments, the strongest warning the FDA uses. The medication may increase the risk of viral infections, and there is a possible, but rare, risk of lymphoma and skin cancer.
Despite the black-box warnings, The American Academy of Dermatology's official position is that it considers appropriate use of the medications under the supervision of a dermatologist to be safe and effective. Many dermatologists treating inverse psoriasis will use these medications first, because they do not carry a risk of skin thinning.
The use of ultraviolet B (UVB) type light is also helpful. To receive treatment, patients undress and stand in a light box, typically at their doctor's office. The light is believed to slow the growth of psoriasis cells.
Although research is lacking, a 2002 case study reported that one patient achieved "complete clearance" of inverse psoriasis lesions after 3 weeks of UVB light treatment. A larger study involving the use of UVB light among those with standard psoriasis reported that about 66% were "90% clear after a maximum of 10 treatments."
Some patients, usually those whose inverse psoriasis is worsened by moisture, have found relief using a product called Castellani's Paint or Castederm. This liquid medication, which contains the active ingredient phenol, comes in both prescription and nonprescription strength. Domeboro astringent soaks, which are available over the counter, can also be helpful.
Patients should be active participants in their health care, which means following doctors' recommendations and tracking triggers that cause flare-ups. Ask about the latest treatments. And, as with any chronic condition, connecting with other patients can reap valuable information as well as emotional support.
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