Patch tests in patients using immunosuppressants and/or cytokine inhibitors: descriptive analysis of 16 cases

1. Chen SX, Cohen PR. Parrot beak nails revisited: case series and comprehensive review. Dermatol Ther (Heidelb). 2018;8:147--55. 2. Forouzan P, Cohen PR. Parrot Beak nail: case report and review of parrot beak nail dystrophy. Cureus. 2021;13:e15974. 3. Marie I, Gremain V, Nassermadji K, Richard L, Joly P, Menard JF, et al. Nail involvement in systemic sclerosis. J Am Acad Dermatol. 2017;76:1115--23. 4. Tunc SE, Ertam I, Pirildar T, Turk T, Ozturk M, Doganavsargil E. Nail changes in connective tissue diseases: do nail changes provide clues for the diagnosis? J Eur Acad Dermatol Venereol. 2007;21:497--503. 5. Chang P, Tello GA, Cohen SEN, Anzueto E. Manifestaciones del aparato ungueal en las enfermedades del colágeno: reporte de 43 casos. Dermatol Cosmet Med y Quir. 2016;14:270--80. 8. Hasson A, Carreño N, Uribe P, Montoya JD. Actualización en desórdenes pigmentarios, patología ungueal y del pelo. Rev Chil Dermatol. 2011;27:8--15. 9. Ricardo JW, Lipner SR. Parrot beak nails and longitudinal melanonychia. J Cutan Med Surg. 2021. 10. Kurokawa M, Isshiki N, Inoue K. A new treatment for parrot beak deformity of the toe. Plast Reconstr Sur. 1994;93:558--60.


Dear Editor,
Patch tests are the reference proof for the etiological diagnosis of allergic contact dermatitis (ACD), related to the delayed type 4 hypersensitivity reaction (Gell & Coombs). 1 The use of drugs that interfere with patient immune response, such as corticosteroids, cyclosporine, methotrexate, azathioprine, mycophenolate mofetil, and the latest cytokine inhibitors (infliximab, adalimumab), could be considered a limitation to undergo patch tests since they act by inhibiting cell responses. On the other hand, the use of these medications has become increasingly common and, often, their withdrawal is not possible due to the underlying disease. Moreover, studies show that many patients are capable of developing eczematous reactions even when using these drugs. 2---5 The present study aimed to investigate suspected cases of ACD submitted to patch testing in a non-ideal situation (patients who were receiving immunosuppressive drugs and/or cytokine inhibitors).
Data from 16 patients tested between 2009 and 2021 and who were using any of the abovementioned medications at the time of the test were retrospectively analyzed. Different series of allergens were used, the indications of which were based on anamnesis and clinical picture.
ଝ Study conducted at the Dermatology Clinic, Santa Casa de São Paulo, São Paulo, SP, Brazil.
The tests were applied to the upper back region and removed after 48 hours. The results were obtained after 48 and 96 hours. The possible reactions were: negative, weakly positive (1+) (erythema, infiltration or papules); strongly positive (2+) (edema and/or vesicles); and very strongly positive (3+) (bullae or ulceration).
The mean age of the patients was 49 years, consisting of 12 women and four men. The median time of the dermatitis was 37 months (3---180 months). The medications used by the patients at the time of the tests were: prednisone in nine cases, methotrexate in seven, azathioprine in four and infliximab, cyclosporine, cyclophosphamide, tacrolimus and adalimumab in one case each. Some patients used more than one medication at the same time. The doses used by the patients varied according to the indication and the disease stage. In the case of prednisone, they varied between 5 and 40 mg per day, and for methotrexate, between 10 and 15 mg per week. Regarding cyclophosphamide, the patient had been submitted to pulse therapy one month before the test with a dose of 1 g, and azathioprine was used at doses of 100 and 150 mg/day.
The reasons for using these medications were difficultto-control eczema (four cases), collagen diseases (systemic and discoid lupus, Behçet's disease and antisynthetase syndrome) in eight cases, Crohn's disease, Cushing's syndrome and psoriasis in one case each.
Among the tested patients, ten (62.5%) had at least one positive test and six (37.5%) had all negative results. One of the cases with a negative initial test was positive in a new test performed after drug withdrawal (methotrexate), a result that was previously relevant. In the new test, positivity was observed for paraphenylenediamine (PPDA); contact and ACD had occurred after the application of a temporary tattoo (''henna'') in adolescence.
After completion of the tests, nine (56.3%) cases were considered to have a final diagnosis of ACD. Other diagnoses LETTER -RESEARCH

Financial support
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Conflicts of interest
None declared.