Psoriasis complicated with polymyositis successfully treated with Ixekizumab: A case report

Psoriasis is an immune-mediated chronic inflammatory skin disease that is rarely complicated by polymyositis in clinical practice. Here, we report a patient with psoriasis, following treatment with Etanercept, who exhibited an increase in creatine kinase (CK) levels and a decline in muscle strength. After combined treatment with methylprednisolone, methotrexate, and Ixekizumab, the psoriasis rash completely subsided and CK levels returned to normal.

The patient was a 22-year-old female with systemic erythema and scale itching for 3 months, and her serum CK level was 1711 U/L without muscle pain and muscle weakness. She was diagnosed with psoriasis and myositis awaiting investigation and was then treated with Etanercept at 50 mg weekly. At the 6-month follow-up with ongoing Etanercept treatment, her serum CK level was elevated to 3465 U/L. Electromyography and thigh magnetic resonance imaging revealed myositis. After methylprednisolone and methotrexate tablet treatment for polymyositis, she developed pulmonary pneumonia, and methotrexate and methylprednisolone tablets were withdrawn. Although the pneumonia was controlled, the facial erythema, plaques, scales, and rash gradually increased and spread all over the body. Moreover, gastrocnemius pain and fatigue persisted. The patient was treated with subcutaneous injection of 160 mg of Ixekizumab combined with methylprednisolone tablet (8 mg/d), after 2 weeks, the dosage was reduced to 80 mg once every 2 weeks, and the patient's psoriastic rash had completely disappeared after 4 weeks. The patient continued to receive subcutaneous injections of Ixekizumab 80 mg once a month and methylprednisolone tablet 6 mg every day. Six months later, no rash recurrence was noted and her CK level was within the normal range.

The patient was diagnosed with psoriasis with polymyositis.

After combined treatment with methylprednisolone, methotrexate, and Ixekizumab, the psoriasis rash completely subsided and CK levels returned to normal.

Our case shows that Ixekizumab is an effective treatment for psoriasis complicated with polymyositis, which is worth clinical application.

Although Etanercept can be used to treat psoriasis and dermatomyositis, it can also aggravate the myositis. Ixekizumab is an effective treatment for psoriasis complicated by polymyositis.