6th February 2024

A 45-year-old male presents to the dermatology clinic with a blistering rash.

A 45-year-old male presents to the dermatology clinic with a blistering rash. He states that this has been ongoing for the past four months, and the old lesions had healed, leaving hyperpigmented patches along the back of his hands, forearms and neck. Examination today reveals an ulcerated lesion along the dorsum of his hand and scalp. Areas of hyperpigmentation are seen along his hands, with small yellowish-white papules along the dorsum of his hand. 

He denies any other associated symptoms. Urinary porphyrin levels are elevated. ALA levels are normal. 

Which of the following is the likely underlying diagnosis?