Psoriasis is best described as:

Explanation: Phototherapy involves exposing the skin to UV light to treat psoriasis. During phototherapy sessions, patients should wear special shields to protect their eyes and genitals from potential UV damage.

Incorrect choices: a. Patients undergoing phototherapy are actually exposed to controlled amounts of UV light, which is different from uncontrolled sun exposure. Phototherapy is a prescribed treatment and should be done under healthcare professional supervision.

b. While phototherapy may cause temporary skin darkening or tanning, it is not associated with permanent changes in skin color.

d. Phototherapy does not increase the risk of skin infections. However, patients with psoriasis should practice good hygiene to prevent infections related to their condition and skin care routine.

Explanation: The development of wheals and hives is not characteristic of psoriasis. Wheals and hives are associated with urticaria (hives), which is a separate skin condition caused by histamine release.

Incorrect choices: a. Pitting and ridging of the nails: Pitting and ridging of the nails are common nail changes seen in psoriasis and can aid in its diagnosis.

b. Koebner phenomenon upon skin trauma: The Koebner phenomenon, where new psoriatic lesions form at sites of skin trauma or injury, is a characteristic feature of psoriasis.

d. Silvery-white scales on erythematous plaques: Silvery-white scales on erythematous (red) plaques are a classic feature of psoriasis and help differentiate it from other skin conditions.