A 28-year-old male with psoriasis, which had failed to respond to topical agents, acitretin, and UV light for 3 years, cleared completely 4 weeks after starting on IL-17i, secukinumab. The patient had a biopsy of the back lesions before using secukinumab and was diagnosed with psoriasis (Figure 1A). At this point, plasma concentrations of cytokine: IFN-gamma: 109.72 pg/mL (normal range< 7.42 pg/mL), IL-17A: 5.64 pg/mL (normal range< 2.90 pg/mL). However, after 8 months of secukinumab treatment, he developed erythema, lichenification, and intense itching. They were mainly on the trunk and in skin folds such as the groin and axillary (Figure 2A1-D1). During this period, the patient did not use any other medication.  
Laboratory test results were as follows: cytokine detection: IL-4: 3.85 pg/mL (normal range< 2.80 pg/mL), IL-6: 317.54 pg/mL (normal range< 5.30 pg/mL), IL-10: 1.15 pg/mL (normal range<4.91 pg/mL). Inguinal skin cells were repeatedly cultured, with only the growth of Staphylococcus aureus but no fungus. No abnormality was found in the hemogram, hepatic and renal function, hemostasis, humoral immunity, autoimmune antibody profile, and T-SPOT.TB test. The skin tissues of the groin were embedded in paraffin for hematoxylin-eosin (H&E) staining. The biopsy specimens showed: (i) epidermal hyperkeratosis with mild focal parakeratosis; (ii) acanthosis with spongiosis; (iii) lymphocytes and little eosinophils infiltrating around the small vessels (Figure 1B). It represents an overlapping histopathological feature of psoriasis and dermatitis. The patient has no family history of psoriasis, atopic dermatitis, or eczema. Eventually, the disease was diagnosed as PsoD.
We stopped secukinumab and started to use systemic therapy, which included glycyrrhizic acid, vitamin C, calcium gluconate, rupatadine fumarate, ebastine, and methotrexate. However, the patient's symptoms did not improve significantly. We then treated him with tofacitinib and discontinued all other treatments. Then, the patient started follow-up in the clinic once a week due to work. One week later, the lesions became smaller, lighter, and pruritus-free (Figure 2A2-D2). Referring to the dosage of tofacitinib in treating immune-mediated inflammatory diseases, we use tofacitinib for six weeks, including 5mg bid for the first four weeks and 5mg qd for the last two weeks. After six weeks, the patient's lesions remained only hyperpigmented, without new lesions (Figure 2A3-D3). We rechecked the blood cytokine and found no abnormalities. Three months after stopping secukinumab treatment, the patient relapsed psoriasis on the scalp. We successfully relieved the lesions with topical 0.005% calcipotriene for 2 weeks. In 3 months of follow-up after discontinuation of tofacitinib, we observed no adverse effects or recurrence of PsoD (Figure 2A4-D4). The patient was very satisfied with both tofacitinib and calcipotriene treatment. The timeline of this case report is shown in Figure 3.