Biologic therapy screening — SCE Dermatology MCQ

Correct answer: C — Assess and treat latent tuberculosis before starting

The correct answer is C, assess and treat latent tuberculosis before starting. A positive hepatitis B core antibody with negative surface antigen and a positive interferon-gamma release assay in an asymptomatic patient with a normal chest X-ray is the classic pattern of latent TB infection rather than active disease. NICE guidance on TNF-alpha inhibitor use mandates that anyone with evidence of latent TB (positive IGRA, with active disease excluded) must complete appropriate chemoprophylaxis, or be established on treatment, before anti-TNF biologics such as adalimumab are started, because TNF-alpha is critical for granuloma maintenance and its blockade risks reactivation and disseminated TB. A normal chest X-ray only excludes active pulmonary disease, it does not exclude latent infection, which is confirmed by the immunological test result here. This patient's history of residence in a high TB-burden country (India) further raises pretest probability, reinforcing the need for formal TB risk assessment and treatment before immunosuppression. Why the other options are wrong: D. Start adalimumab because the chest X-ray is normal: a normal film excludes active disease but latent infection can reactivate under TNF blockade, so biologic therapy must not proceed until latent TB is addressed. E. Begin adalimumab with live varicella vaccination: live vaccines are contraindicated once significant immunosuppression is established or imminent, and vaccination does not address the TB risk at all. A. Avoid every biologic permanently: latent TB is treatable; once chemoprophylaxis is completed, biologics including adalimumab can be used safely, so permanent avoidance is unnecessary. B. Use systemic prednisolone while awaiting screening: corticosteroids are themselves immunosuppressive and can worsen TB risk and psoriasis (rebound flare on withdrawal), offering no benefit while screening is pending. Key point: A positive IGRA with a normal chest X-ray indicates latent TB, which must be treated before, not after, starting anti-TNF biologic therapy.

Reference: NICE Guideline NG33, Tuberculosis (2016, updated), section on TNF-alpha inhibitor therapy and latent TB screening/treatment; https://www.nice.org.uk/guidance/ng33