[Two cases of hypertrichosis cubiti].

Hypertrichosis cubiti, also known as hairy elbows syndrome, is an uncommon form of localized congenital hypertrichosis in which an excessive amount of long, fine, lanugo-type hair is found on skin of normal texture and morphology. The hair growth follows a bilateral symmetrical distribution and affects the extensor surface of the distal third of the upper arms and the proximal region of the forearms. The condition usually appears appeared on her foot. The patient tried her right shoe on her left foot, and after a few hours lesions appeared on the foot along with distant lesions on her chest. Patch testing was performed with a standard series and a shoe series, the latter proving positive for 4-aminoazobenzene; however, there was no cross-reactivity with paraphenylenediamine (Figure 3). The rubber and dyed leather of the shoe were also patch tested and the reaction was positive. The definitive diagnosis was contact dermatitis caused by shoe dye. Since she stopped using the shoes, the patient has not presented further lesions. Therefore, we describe a case of unilateral contact dermatitis caused by footwear. This atypical presentation delayed diagnosis and led us to consider different options, such as factitious dermatitis. Footwear contact dermatitis typically presents bilaterally and commonly affects the dorsa of the feet. Diagnosis is made difficult by the existence of atopic dermatitis and preexisting or overlapping infection. Moreover, other conditions that can be misdiagnosed, such as nummular eczema, tinea pedis, dyshidrotic eczema, contact dermatitis caused by topical medication, etc.1,2 4-Aminoazobenzene is an intermediate in the production of diazo dyes used in the textile and footwear industry. Cross-sensitivity between azo dyes and para-amino compounds such as phenylenediamine is common,3,4 although in our case we did not observe cross-reactivity. Since the year 2000, the Contact Unit of the Dermatology Service of Hospital General Universitario in Valencia, Spain, has recorded 82 cases of contact dermatitis due to footwear. As was the case in other series,5 potassium dichromate was the most common allergen (86.5%), and other less commonly involved allergens were 4-tert-butylphenol-formaldehyde resin, 2-mercaptobenzothiazol, nickel, and paraphenylenediamine. Only 2 of our cases involved aminoazobenzene, and in 1 there was cross-reactivity with paraphenylenediamine. The mean age of diagnosis was 34 years and the ratio of men to women was 1:3. This dermatitis presented most commonly on the dorsa of the feet. The conditions diagnosed before contact dermatitis were dyshidrotic eczema, neurodermatitis, lichen simplex chronicus, psoriasis, and dermatitis artefacta, as in our case. Letters to the editor