What is inverse psoriasis?

Inverse psoriasis (also known as intertriginous psoriasis) mainly affects the skin in the armpits, groin, under the breasts, between the buttocks, and around the genitals. It is also known as flexural psoriasis because it affects areas of the body that regularly ‘flex’ and fold. In young infants, it can be called “napkin psoriasis” due to the involvement of the diaper area.¹ Common triggers for inverse psoriasis are similar to those of plaque psoriasis and include certain medications, infections, injury to the skin, stress, and excessive tobacco or alcohol use. Due to it being located in skin folds and on sensitive skin, it is also easily worsened by rubbing and sweating.

Symptoms

The lesions associated with inverse psoriasis, like most other types of psoriasis, can be itchy and painful. However, it usually lacks the typical scaliness of other forms of psoriasis, due to the moist environment in which it normally occurs. In appearance, the lesions will look like shiny, red, clearly outlined patches of skin, and because they occur in the creases of your skin, they can cause cracks or fissures, which may be painful and bleed.

Diagnosis

Inverse psoriasis, like plaque psoriasis, is clinically diagnosed, meaning that your doctor will take a thorough medical history and do a full physical examination, including taking a close look at your skin. They may ask you questions about when or how you first noticed your lesions, what other symptoms you have, and what parts of your body are affected.² A skin biopsy, where a small sample of the lesion is sent to the pathologist to view under a microscope, may sometimes aid in the diagnosis.³ Sometimes inverse psoriasis can be mistakenly diagnosed as a fungal or bacterial infection, or even develop an overlying fungal or bacterial infection if the affected areas are not kept clean and as dry as possible.¹

Treatment

While inverse psoriasis cannot be cured, there are many effective treatment options. The mainstay of treatment for patients with inverse psoriasis is topical corticosteroid, calcipotriol, or calcineurin inhibitor therapy. Topical steroids work through their anti-inflammatory and immunosuppressive properties but should be used in a low- to mid-potency formula for inverse psoriasis to prevent skin thinning in areas where the skin is already very sensitive. In the case that topical therapy is not effective or if the inverse psoriasis is severe, oral medications or injectable biologics, can be considered.¹

References

1. Micali G, Verzì AE, Giuffrida G, Panebianco E, Musumeci ML, Lacarrubba F. Inverse Psoriasis: From Diagnosis to Current Treatment Options. Clin Cosmet Investig Dermatol. 2019;12:953-959.
2. Kim WB, Jerome D, Yeung J. Diagnosis and management of psoriasis. Can Fam Physician. 2017;63(4):278-285.
3. Johnson MAN, Armstrong AW. Clinical and histologic diagnostic guidelines for psoriasis: a critical review. Clin Rev Allergy Immunol. 2013;44(2):166-172.