Pirfenidone-Induced Photosensitivity in a Patient with Idiopathic Pulmonary Fibrosis

A Case of Pirfenidone-Induced Photosensitive Drug Eruption

A 75-year-old male was diagnosed with idiopathic pulmonary fibrosis and treated with pirfenidone. He presented with an erythematous thick scaly patch on his face, neck, and both hands and arms. He had a history of significant exposure to sunlight without using sunscreen. All lesions were restricted to sun-exposed areas and appeared one month ago. Histopathological examination revealed necrotic keratinocytes, epidermal spongiosis, liquefaction degeneration of the basal layer, interface dermatitis, solar elastosis, and upper dermal perivascular lympho-histiocytic infiltration. Based on clinical and histopathological findings, the skin lesion could be diagnosed as photosensitive drug eruption induced by pirfenidone. Pirfenidone was discontinued for a month, and the patient was treated with oral and topical corticosteroids. Consequently, the skin lesion almost fully cleared, leaving mild postinflammatory hyperpigmentation. Although there are many reports of photosensitivity reactions to pirfenidone, dermatologists are still not familiar with this drug. Through this case presentation, clinicians should be aware of the potential phototoxic effects of pirfenidone and provide the necessary precautionary information to patients who take pirfenidone.

Retrospective analysis of skin photosensitivity induced by pirfenidone

WHAT IS KNOWN AND OBJECTIVE

Knowledge regarding the association between photosensitivity and pirfenidone is based mainly on case reports. The purpose of this article was to evaluate the clinical characteristics of photosensitivity associated with pirfenidone.

METHODS

We collected studies on photosensitivity induced by pirfenidone published from 2008 to 31 August 2021 in Chinese and English for a retrospective analysis.

RESULTS AND DISCUSSION

The median age was 70 years (range 57-80) in 22 patients with pirfenidone-induced photosensitivity. The dose at the onset of symptoms ranged from 600 to 2403 mg for the treatment of idiopathic pulmonary fibrosis. Pirfenidone-induced photosensitivity occurred within 1 week in some patients and up to 8 months in others. The most common clinical manifestation of photosensitivity caused by pirfenidone was itching on body parts exposed to sunlight (back of hands, face, neck, and limbs) in 15 patients followed by erythema in 13 patients. Histopathological examination revealed necrotic keratinocytes, lymphocytic inflammatory cell infiltrate, hyperkeratosis and liquefaction degeneration in 5 patients. The photosensitivity test showed a markedly decreased minimum erythema dose (MED) of 7-228 mJ/cm² UV-B in 4 patients and 4.86-12 J/cm² UV-A in 5 patients. The clinical symptoms were significantly improved or completely relieved with a median time of 4 weeks (range 1-8) after drug withdrawal, dose reduction or systemic and topical glucocorticoid therapy.

WHAT IS NEW AND CONCLUSION

Clinicians should be aware of the potential phototoxic effects of pirfenidone and should inform patients to take pirfenidone during (or after) a meal, avoid sun exposure, wear protective clothing, and apply broad-spectrum sunscreen with high ultraviolet UVA and UVB protection.