Photosensitive psoriasis mimicking cutaneous lupus erythematosus: a case report

Photosensitive presentations of psoriasis are often under-recognized and may closely mimic other photodistributed dermatoses. We report the case of a 39-year-old male patient with no history of other photodermatoses who developed a progressive, non-pruritic rash, localized in sun-exposed skin areas, with marked exacerbation after phototherapy. Pronounced photosensitivity and atypical lesion distribution, involving the malar and nasal regions, complicated the initial differential diagnosis between photosensitive plaque psoriasis and cutaneous lupus erythematosus (CLE). Only further clinical evaluation, alongside histopathological analysis and immunological testing, helped to confirm the final diagnosis of photosensitive plaque psoriasis. Treatment with systemic and topical corticosteroids, vitamin D analogues, and calcineurin inhibitors resulted in gradual clinical improvement. This case report highlights photosensitive psoriasis as an important cause of photodistributed eruptions and a rare but significant mimic of CLE.