Baboon Syndrome Induced by Hydroxyzine
A 60-year-old man started treatment with hydroxyzine (Atarax®; UCB Pharma, France) and meprobamate (Equanil®; Sanofi-Aventis, France) for anxiety. Previously, he had taken frequently hydroxyzine without any incident. After 2 days, he developed a pruritic symmetrical erythema with few small pustules on both inner thighs, cubital fossae, axillae, and the gluteal area [Figures and ]. The patient denied any intake of other medications during the previous weeks and had no history of mercury exposure. There was no fever and laboratory tests (complete blood cell count and C-reactive protein) showed only eosinophilia (800/ml). Blood and pustule cultures were negative. The mycological examination of a pustule was negative. A baboon-type drug reaction was suspected. Skin biopsy showed a perivascular lymphohistiocytic infiltrate with eosinophils and some neutrophils in the dermis. Some subcorneal pustules were also seen. The clinical and histopathological findings were consistent with a pustular drug-related baboon syndrome. The two drugs were discontinued and the lesions resolved within 4 days without any medications. One week later and despite our recommendations, the patient took again one tablet of hydroxyzine. Few hours after restarting therapy, an acute episode of baboon syndrome developed. Hydroxyzine was stopped and the lesions resolved within 1 week. One month after complete resolution, the patient was patch tested with European standard series, metals series, ethylenediamine dihydrochloride (1% pet.), meprobamate (30% pet. and 30% in water), hydroxyzine (30% pet. and 30% in water), cetirizine (30% pet. and 30% in water), and levocetirizine (30% pet. and 30% in water).[] Reactions were evaluated at D2 and D3 according to ICDRG guidelines. Only the patch tests with hydroxyzine were positive at D2 (+) and D3 (++). At D4, the positive patch test with hydroxyzine (30% pet.) showed pustular formation []. Oral provocation tests with cetirizine and levocetirizine were negative. In view of the positive reactions obtained with the patch test and the oral accidental provocation test, the diagnosis of hydroxyzine-induced baboon syndrome was confirmed. The patient restarted his treatment with meprobamate without any incident.