Frequency and spectrum of myopathies in patients with psoriasis

Psoriasis is a T-cell-mediated skin disorder with uncommon extracutaneous manifestations. Rare patients with psoriasis and myopathy have been reported.

We conducted a retrospective review of medical records of psoriasis patients seen at the Mayo Clinic during the period from January 1, 1996 to May 31, 2011. Patients who had pathologically confirmed myopathy or lymphocytic infiltrates in muscle were included.

Among 11,370 psoriasis patients, 13 had pathologically confirmed myopathies. Seventy percent were inflammatory myopathies, and 2 had focal inflammation in the muscle. Psoriasis preceded myopathy onset in two-thirds of the patients (median 14.7 years). Half of the patients had psoriatic arthritis; 60% had other autoimmune disorders. Patients who received anti-tumor necrosis factor-alpha (anti-TNF-α) therapy had a higher risk for developing myopathy or inflammation in muscle (odds ratio = 4.45).

Myopathy or inflammation in muscle affects an average of 1.32 of every 1000 psoriasis patients. Concomitant autoimmune disorders, psoriatic arthritis, and exposure to anti-TNF-α therapy may be associated with increased risk of developing myopathy in psoriasis patients.