An unusual side effect of isotretinoin: retinoid dermatitis affecting external urethral meatus.

Isotretinoin (Iso) is the most effective drug against severe nodulocystic acne. As a synthetic oral retinoid, Iso exerts its actions by modulating cell growth and differentiation. Targeting all the pathophysiologic processes in acne development, Iso has been considered to be an unique drug, however it has several side effects. While chelitis, xerosis, ocular sicca, arthralgia, myalgia, headache, hyperlipidemia are the most common side effects, teratogenicity and depressive symptoms are the most concerning ones. In addition, Iso has unusual side effects which have been described for the first time in the literature. Here, we report a remarkable side effect of Iso in a 23-years-old male patient with retinoid dermatitis affecting the external uretral meatus. To our knowledge, only few cases of retinoid dermatitis in the urethral mucosa due to Iso have been reported in the literature so far.