Introduction
The advent of anti-TNF alpha has changed the management of chronic inflammatory rheumatism. However, paradoxical effects have been described often resulting in skin lesions including psoriasis. We report three observations.
Cases report:
Case 01: A 46-year-old man with no personal or family history of psoriasis, known  for ankylosing spondylitis treated with etanercept. He developed plaque type psoriasis and palmoplantar pustulosis three months after starting the treatment, which lead to stopping the anti-TNF α agent. The evolution was satisfying with topical corticosteroid and optimization of methotrexate.
Case 02: A 51-year-old man was treated with adalimumab for ankylosing spondylitis, after two years of treatment, psoriasis in gout appeared in the abdomen, back and legs. There was complete remission of cutaneous lesions with topical corticosteroid and anti-TNF-α therapy was not suspended. One year later, psoriasis reappeared in the same locations.
Case 03: A 40-year-old woman with no personal or family history of psoriasis was treated with adalimumab for a rheumatoid arthritis. After five years of treatment, extensive psoriasiform lesions appeared. Psoriasis regressed rapidly after discontinuation of adalimumab.
Conclusion:
Psoriasiform rash is the most commonly reported skin side effect during anti-TNF alpha therapy. If their clinic is now well known their pathogenesis remains controversial. Their onset does not usually require stopping the anti-TNF that might be continued or replaced by another.

Psoriasis Induced by Anti-Tumor Necrosis Factor Alpha Agents: three cases