Psoriasis — SCE Dermatology MCQ

Instant feedback + full explanation. One question, done properly.

EasyPhotobiologyPsoriasisSCE Dermatology

A 55-year-old man with moderate plaque psoriasis affecting his scalp, elbows, and knees (PASI 10, DLQI 12) is being considered for narrowband UVB phototherapy. He is on no systemic medications. What is the recommended treatment frequency?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Two to three times weekly

BAD guidelines recommend narrowband UVB phototherapy delivered 2-3 times weekly (typically thrice weekly, minimum twice weekly) for psoriasis. A typical course is 20-30 treatments. Starting dose is based on the patient's MED (minimal erythema dose) or Fitzpatrick skin type, with incremental dose increases (typically 10-20% per session if no erythema). Maximum recommended lifetime exposure varies but there is no strict numerical limit as for PUVA, though cumulative dose monitoring is recommended. NB-UVB can be combined with topical therapy but Dithranol should not be applied before treatment.

Reference: BAD 2019 Phototherapy Guidelines