Letter: Photodistributed reticulated hyperpigmentation related to diltiazem.

Diltiazem is a calcium channel blocking agent used for the treatment of hypertension. Cutaneous adverse effects are uncommon. The most frequently reported are itching, urticaria, and maculopapular eruption. A peculiar, cutaneous photodistributed reticulated hyperpigmentation secondary to diltiazem has been recently reported. A 66-year-old white woman with a 2 year history of pruritic hyperpigmented lesions on her face was seen in the clinic. Past medical history was remarkable for hypertension, which had been treated with diltiazem. Physical examination showed slate-gray to brown reticulated hyperpigmentation in the photo-exposed areas of the face and neck. Histological examination revealed interface dermatitis with liquefactive degeneration of the basal layer, necrotic keratinocytes, lymphocytic inflammatory infiltrate, and melanophages in the superficial dermis. A diagnosis of diltiazem-induced hyperpigmentation was established and diltiazem was stopped. Gradual resolution of the hyperpigmentation was observed over the following months. Although diltiazem has been marketed for over 20 years, the first cases of this particular type of reticulated hyperpigmentation were described in 2001. Since then, to our knowledge, only 17 cases have been reported in the literature. In all cases, cutaneous lesions appeared at least 6 months after this treatment had been started. Hyperpigmentation was controlled by means of photoprotection and discontinuation of diltiazem. Diltiazem can produce a characteristic lichenoid dermatitis with reticulated hyperpigmentation on sun-exposed areas.