a 20-year - old female with extensive terminal ileal and colonic crohn 's disease was initially successfully managed on a drug regimen of prednisolone and mesalazine which helped to induce remission . this maintained her disease remission but was associated with neutropenic sepsis , necessitating the withdrawal of the thiopurine therapy with subsequent clinical and endoscopic disease flare . this required an infusion dose and frequency escalation to maintain clinical response . after 58 weeks of infliximab therapy , the patient was requiring 10 mg / kg 6 times weekly and hence was transferred to the fully human anti - tnf- injection adalimumab for loss of response to infliximab . initially this strategy regained disease control , but due to relapse at 40 mg every other week , the dose was increased step - wise to 80 mg weekly which fortunately maintained remission . during her treatment with adalimumab the presence of purple - coloured plaque - like lesions primarily on her abdomen figure 1 demonstrates the presence of psoriasis which is presumed to be a result of treatment with adalimumab . tnf- has been identified as a key cytokine in the pro - inflammatory pathways that drive diseases such as inflammatory bowel disease and rheumatoid arthritis . anti - tnf- agents such as infliximab and adalimumab are widely used in the treatment of these conditions and have been shown to have an impact on pro - inflammatory and apoptotic pathways . they are also effective in the treatment of the dermatological and rheumatological manifestations of psoriasis . however , there have been a number of cases reported where such agents may be responsible for new onset or worsening of psoriasis . a study of 126 patients who underwent treatment with anti - tnf- inhibitors demonstrated evidence of psoriasis in 76 individuals , palmoplantar pustular psoriasis in 37 cases and psoriasis of the nails in 6 cases . there is mounting evidence that a key innate immune pathway for triggering common human autoimmune diseases , including psoriasis , involves plasmacytoid dendritic cell precursors and type 1 interferon ( ifn ) production . a recent study involving immunohistochemical staining of skin biopsy specimens for myxovirus - resistance protein a ( mxa , a surrogate marker for lesional type 1 ifn activity ) demonstrated increased staining in tnf- inhibitor - induced psoriasis compared with psoriasis vulgaris . research suggests that a psoriasiform eruption during anti - tnf- treatment seems to be a class effect without any confirmed predisposing factors and does not specifically require treatment discontinuation . further studies are however needed to determine the exact mechanism of and appropriate treatment for anti - tnf--induced psoriasis .