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Occasionally, it can be difficult to differentiate eczematous dermatitis from psoriasis. This is when a biopsy can be quite valuable to distinguish between the two conditions. Of note, both eczematous dermatitis and psoriasis often respond to similar treatments. Certain types of eczematous dermatitis can be cured where this is not the case for psoriasis.
Plaque psoriasis signs and symptoms appear as red or pink small scaly bumps that merge into plaques of raised skin. Plaque psoriasis classically affects skin over the elbows, knees, and scalp and is often itchy. Although any area may be involved, plaque psoriasis tends to be more common at sites of friction, scratching, or abrasion. Sometimes pulling off one of these small dry white flakes of skin causes a tiny blood spot on the skin. This is a special diagnostic sign in psoriasis called the Auspitz sign.
Fingernails and toenails often exhibit small pits (pinpoint depressions) and/or larger yellowish-brown separations of the nail from the nail bed at the fingertip called distal onycholysis. Nail psoriasis may be confused with and incorrectly diagnosed as a fungal nail infection.
Symptoms and signs of guttate psoriasis include bumps or small plaques (½ inch or less) of red itchy, scaling skin that may appear explosively, affecting large parts of the skin surface simultaneously, after a sore throat.
In inverse psoriasis, genital lesions, especially in the groin and on the head of the penis, are common. Psoriasis in moist areas like the navel or the area between the buttocks (intergluteal folds) may look like flat red plaques without much scaling. This may be confused with other skin conditions like fungal infections, yeast infections, allergic rashes, or bacterial infections.
Erythrodermic psoriasis appears as extensive areas of red skin often involving the entire skin surface. Patients may often feel chilled.
Scalp psoriasis may look like severe dandruff with dry flakes and red areas of skin. It can be difficult to differentiate between scalp psoriasis and seborrheic dermatitis when only the scalp is involved. However, the treatment is often very similar for both conditions.
"Treatment of psoriasis in adults"