Dermatology - Inverse Psoriasis

Dermatology - Inverse Psoriasis 
Psoriasis is usually a chronic condition. In addition to environmental factors like stress, bacterial infections, trauma, or specific medications, there is a polygenic tendency. With peaks at the ages of 8, 22, and 55, onset can happen at any age. More severe disease is predicted by an early beginning. Lesions that persist for months or years affect the majority of patients.

Pruritus is prevalent, particularly in the anogenital and scalp areas

Plaques in the body folds are macerated, frequently bright red and fissured (inverse psoriasis), and lesions from intertrigo, candidiasis, or contact dermatitis can only be distinguished by a strong demarcation. In some regions, polycyclic, geographic lesions may arise from strongly marginated, dull-red plaques with loose lamellar, silvery-white scales. These could exhibit arciform, serpiginous, and annular patterns if they partially retreat. Removal of lamellar scales is simple, unless the lesion is very persistent. Lesions can be single or many, localizing to the sacralgluteal area, scalp, elbows, knees, palms, and soles—the predilection sites.
Lesions frequently spare exposed areas and exhibit bilateral symmetry. Massive hyperkeratosis with a sharply delineated foundation that is either silvery white or yellowish on the palms and soles is difficult to eliminate. Bleeding, painful fissures, and cracking are possible. Pitting, subungual hyperkeratosis, onycholysis, and yellowish-brown patches beneath the nail plate—known as the "oil spot" (pathognomonic)—are among the nail abnormalities.
Differential diagnosis and diagnosis
The differential includes seborrheic dermatitis, lichen simplex chronicus, drug eruptions, tinea, and mycosis fungoides. The diagnosis is clinical. Intertrigo, extramammary Page disease, glucagonoma syndrome, Langerhans cell histiocytosis, and Hailey-Hailey disease are among the conditions on the differential for inverse psoriasis. Onychomycosis in the nails needs to be ruled out using KOH.

Topical fluorinated glucocorticoids with occlusion can be used to treat plaques; hydrocolloid dressing works well and keeps patients from scratching. It is beneficial to inject a 3 mg/mL triamcinolone acetonide aqueous suspension diluted with normal saline into lesions that are less than 4 cm.
Although less efficacious, vitamin D analogues, tacrolimus 0.1%, and pimecrolimus 1% are good nonsteroidal agents. The use of 1% topical pimecrolimus is beneficial for inverse psoriasis.

​Class II topical glucocorticoids work best when paired with tazarotene, which has comparable efficacy.
All topicals can be used in conjunction with either PUVA photochemotherapy or 311-nm UVB phototherapy.
On the scalp, tar or ketoconazole shampooing works well, but firstly, 10% salicylic acid must be used to eliminate plaques. This is followed by betamethasone valerate. Topical therapies have no effect on nail lesions.