Pirfenidone-associated lichenoid-spectrum eruption and photodistributed dermatitis in idiopathic pulmonary fibrosis: a two-case report

Pirfenidone is an antifibrotic agent widely used for treating idiopathic pulmonary fibrosis (IPF). Photosensitivity and rash are the most frequently reported dermatological adverse effects associated with this medication. Nevertheless, several rare pirfenidone-related dermatological reactions have been described in the literature. Herein, we present two cases of rare dermatological adverse effects that occurred during pirfenidone treatment. The first case involved a 69-year-old woman who developed a generalized pruritic rash in the fifth month of pirfenidone treatment. Dermatological examination revealed erythematous papules and plaques on the trunk and the extremities. Histopathological evaluation of the skin biopsy showed a spongiotic and focal interface dermatitis pattern with pityriasis lichenoides chronica-like features, and the overall clinicopathological assessment suggested a possible pirfenidone-associated pityriasis lichenoides-like drug eruption. Following discontinuation of pirfenidone treatment and initiation of systemic and topical therapy, marked regression of the lesions was observed. The second case was that of a 73-year-old man who presented with photodistributed hyperpigmented plaques that developed after sun exposure in the fourth month of pirfenidone treatment. The clinical findings were consistent with pirfenidone-induced photocontact dermatitis. In addition, dark colored vascular lesions prone to hemorrhage, described as venous lake were observed on the lower lip. Dermatological findings regressed after temporary interruption of pirfenidone treatment; however, because of the recurrence of the lesions, the treatment was permanently discontinued. Dermatological adverse effects during pirfenidone treatment may not be limited to photosensitivity reactions. Lichenoid drug reactions and other uncommon cutaneous or mucocutaneous findings may be observed during pirfenidone therapy, although causality should be interpreted cautiously. These cases aim to increase awareness of rare dermatological adverse reactions that may develop in patients receiving pirfenidone treatment.