Latanoprost is a phenyl-substituted analogue of prostaglandin F2α that is used to treat glaucoma. 1 Recently, it has been shown to stimulate eyelash hypertrichosis, and it has therefore been proposed as a possible treatment for alopecia. 2 Despite the extensive use of the drug in ophthalmology, allergic contact dermatitis (ACD) caused by latanoprost has rarely been reported in glaucoma patients. 3-6 We report a case of ACD very probably caused by latanoprost used for the treatment of alopecia areata in a woman.
CASE REPORTA 58-year-old woman was referred to us with itchy eczema of her scalp, face, and neck. The dermatitis appeared after 2 months of topical treatment with 2 mL daily of a galenic preparation composed of minoxidil and latanoprost (minoxidil 5%, latanoprost 0.02%, propylene glycol 15%, and ethanol/water 70:30 79.98%) for diffuse multifocal alopecia areata. The patient reported that she had used minoxidil 2% solution for 5 months previously, without any skin reaction. The NAPOLITANO ET AL. 67 above topical treatment was stopped, and systemic and topical corticosteroid therapy was started. Almost complete clearance of the dermatitis was achieved after 7 days of treatment.After informed consent had been obtained, patch testing with the Società Italiana di Dermatologia Allergologica Professionale e Ambientale (SIDAPA) baseline series, propylene glycol 5% pet., eth. "as is"(FIRMA, Florence, Italy), the galenic preparation "as is" and freshly prepared minoxidil 5% eth. was performed with 8-mm chambers. Readings were performed on day (D) 2 and D4. A positive reaction (+) only to the galenic preparation was noted on D2. Later, other patch tests were performed with 0.005% latanoprost eyedrops (Xalatan; Pfizer, Madrid, Spain), with a positive (+) result (Figure 1), and with the preservative benzalkonium chloride 0.1% aq. (FIRMA) contained in Xalatan eyedrops, with a negative result. Moreover, a repeated open application test was performed with the galenic preparation applied twice daily on the patient's right antecubital fossa, and resulted in a pruritic, eczematous rash after 3 days (Figure 2).
DISCUSSIONSince the introduction of latanoprost in 1996, some adverse reactions have been reported, the most frequent being conjunctival hyperaemia, hypertrichosis, and hyperpigmentation. 2 ACD caused by latanoprost is apparently a very rare side-effect. 3 Indeed, there are only four published cases of hypersensitivity to latanoprost 3-6 and one published case of hypersensitivity to bimatoprost, which is another prostaglandin F2α analogue. 7 In the case reported here, skin tests and the clinical presentation were highly suggestive of ACD caused by latanoprost.Moreover, to the best of our knowledge, all of the published cases concerned ophthalmic treatment, whereas the current case is the first to be reported after the use of latanoprost for alopecia. Given that the use of latanoprost for the treatment of alopecia is increasing, patients suspected of developing ACD should undergo patch testing to determine the causative...