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its response to treatment. Over the last decade, better understanding of these immunological processes has allowed the development of new therapeutic targets, with excellent promise for improved outcomes, especially in moderate-to-severe forms of the disease. However, psoriasis treatment continues to be a challenge, as no cure has been found, and no known therapy can satisfactorily control some aspects. Psoriasis in certain locations, such as the palms and soles, nails, scalp and skin folds, has traditionally been considered difficult to treat, although the literature does not contain evidence indicating that these areas are really more resistant to biologic treatment. In this issue of the BJD, Hjuler et al. investigate the body locations where psoriasis is refractory to treatment with biologics or apremilast in clinical practice, generating evidence on the areas that are truly difficult to treat and the potential effects on patients’ quality of life. This observational study included 146 patients with moderate-to-severe psoriasis who were receiving adequate treatment with biologics or apremilast. The areas that were most resistant to treatment were the legs and elbows (that is, the most typically affected areas in this disease), along with the scalp. On the other hand, most other areas that are usually considered hardest to treat, like the palms, soles, nails or flexors, showed less persistence. These findings suggest that there are misconceptions around the areas that are truly most refractory to treatment in psoriasis, as lesions on the nails or scalp may be difficult to treat topically, but they could respond better to efficacious systemic treatment like biologics. Moreover, the authors observe that overall, the persistence of psoriasis in these areas does not entail a negative impact on patients’ quality of life, challenging the conventional wisdom around these cases in patients treated adequately with biologics. In summary, the results presented in this small but interesting study in clinical practice represent an advance in our understanding of persistent psoriasis in the era of biologics, and they pave the way for clarifying which areas should really be considered difficult to treat and which should be considered special locations for other reasons. In fact, the true justification for identifying these ‘difficult areas’ should reside in the possible differences in the pathogenesis of psoriasis, based on the clinical behaviour or epidemiology of the disease. However, larger studies will be necessary to definitively clarify the truly resistant areas in patients receiving biologics.