Although psoriasis has been recognized at least since Biblical times, new forms, associations and influences continue to be described in the twentieth century. New forms include the rupioid, erythema annulare centrifugum-like and follicular patterns. Associations with vitiligo, bullous pemphigoid and lupus erythematosus have been recently described. Endoscopic surgery has increased para-umbilical psoriasis while Sun Smart campaigns have reduced photo-aggravated psoriasis. Infections such as paediatric perianal streptococcal cellulitis and drugs including angiotensin converting enzyme inhibitors and cytokines exacerbate psoriasis.