Inverse psoriasis is a type of psoriasis that occurs in the armpits, under the breasts, groin, genitals, in the crease between the thigh and groin, and other skin folds
In some cases, especially when rashes appear as the only manifestation of the disease, other diagnostic methods that can be used include:
- Skin biopsy or histopathology: This involves taking a sample of the affected skin and examining it under the microscope. Inverse psoriasis may present with the classical histopathological findings of plaque psoriasis (epidermal hyperplasia and elongation of rete ridges with acanthosis, parakeratosis, thinning of the suprapapillary plates, and reduction of the granulosus layer). However, epidermal hyperplasia is less pronounced, and spongiosis is more common in inverse psoriasis compared to classical plaque psoriasis.
- Dermoscopy: This may show the characteristic presence of whitish scales and red dots homogeneously distributed within the entire plaque.
- Reflectance confocal microscopy (RCM): Although currently available only in some selected academic centers due to the high cost, this is a noninvasive technique that is useful for the differential diagnosis of other inflammatory genital disorders.
What causes inverse psoriasis?
It is estimated that psoriasis affects about 2% of the population, approximately 3%-7% of whom develop inverse psoriasis.
The exact cause of inverse psoriasis is unknown. However, experts believe that it is associated with an overreaction of the immune system that triggers inflammation and exaggerated new skin cell growth.
Inverse psoriasis often runs in families, indicating a genetic trigger. A flare-up of inverse psoriasis can be caused by:
- Skin injuries
- Streptococcal infections
- Injuries, such as injections, sunburn, or a scratch
- Larger skin folds due to obesity
- Excessive perspiration
- Certain prescription medications
How does inverse psoriasis affect the body?
Rashes associated with inverse psoriasis are often damp, shiny, smooth, and discolored (brown, red, or purple).
The main difference between psoriasis and inverse psoriasis is that inverse psoriasis does not feature thick, scaly plaques like other types of psoriasis. This is most likely because of its presence in the moist areas of the body.
The condition commonly affects moist and sensitive areas of the skin that rub against each other, such as:
- Crease of neck
- Skin folds around the genitals and between the buttocks
- Under the breasts
- Between the abdominal folds
- In the groin or inner thighs
- Around the penis, scrotum, or vulva
These lesions can cause painful and bleeding cracks (fissures) in the creases of the skin, as well as:
- Irritation and itching from rubbing and sweating
- Bacterial, yeast, and fungal infections
- Sexual problems due to pain and discomfort
Psoriasis causes the top layer of skin cells to become inflamed and grow too quickly and flake off.
What are the symptoms of inverse psoriasis?
Symptoms of inverse psoriasis include:
- Shiny, smooth, discolored (brown, pink, purple, or red) rash
- Cracks (fissures) in creases of the skin
- Itching and irritation
- Moist skin
If the rash is infected, symptoms may include:
What are complications of inverse psoriasis?
Complications of inverse psoriasis include:
- Irritation due to sweating
- Secondary fungal or yeast infections, especially Candida albicans
- Lichenification (thickening of the skin) from rubbing and scratching, specifically around the anus
- Sexual difficulties (due to embarrassment and discomfort)
- Thin and discolored skin from the long-term overuse of strong topical steroid creams