Psoriasis flare-up on the arm of a 54 year old male patient that is undergoing treatment with the drug adalimumab (marketed under the name Humira). Psoriasis is a skin condition where excessive growth of skin cells can lead to itchy, scaly, thickened patches (plaques) of skin which may become infected. Psoriasis is sometimes triggered by emotional stress, some infections or drugs, although often the cause is unknown. Adalimumab is a human monoclonal antibody that targets excess tumour necrosis factor (TNF) in the body, overproduction of which causes inflammation, swelling, and pain.