Patch tests in Sézary syndrome and mycosis fungoides

A retrospective series of 34 patients with the diagnoses of Sézary syndrome, pre‐Sézary syndrome, or mycosis fungoides had had patch testing. Of these, 27 had at least 1 positive reaction (11 of 12 with pre‐Sézary syndrome, 6 of 10 with Sézary syndrome, and 10 of 12 with mycosis fungoides). The highest average number of positive reactions was observed in patients with pre‐Sézary syndrome (4.7 per patients). There was no predominance of positive reactions to any one allergen, but 13 of the 27 patients reacted to a metal allergen. Only 1 of 5 patients who had photopatch testing had a positive result. This retrospective study revealed delayed contact hypersensitivity response in this group of patients and should serve as a basis for prospective consideration of contact dermatitis factors in patients with mycosis fungoides and Sézary states.