A Challenging Case: Symmetrical Drug Related Intertriginous and Flexural Exanthem, Fixed Drug Eruption, or Both? Esen O ¨ zkaya, M.D., and Goncagu¨l Babuna, M.D. Department of Dermatology and Venereology, _ Istanbul Medical Faculty, _ Istanbul University, _ Istanbul, Turkey Abstract: We herein report a 12-year-old boy with amoxicillin-induced, recurrent, site-specific, symmetrical, sharply demarcated reddish plaques on the buttocks and the major flexural and intertriginous areas. The lesions resolved with topical corticosteroids, leaving hyperpigmentation. Histo- pathology showed nonspecific features of inflammation and dermal melanophages. Amoxicillin was the probable inducer based on oral provo- cation test with Amoksina Ò tablet, however patch testing with amoxicillin on previously affected and unaffected skin remained negative. The diagnosis was challenging because of the overlapping features of symmetrical drug- related intertriginous and flexural exanthema and fixed drug eruption. This one represents a unique and challenging one with overlapping clinical fea- tures of symmetrical drug-related intertriginous and flexural exanthem (SDRIFE) and fixed drug eruption (FDE). We discuss the possible immuno- pathogenetic mechanisms leading to the simultaneous occurrence of dif- ferent phenotypes of drug eruption in the same patient. CASE REPORT A 12-year-old non-atopic Turkish boy presented with symmetrical, well-defined, sharply demarcated, round to oval, slightly elevated reddish plaques 3–20 cm in diameter on the buttocks; the flexural aspect of the femoral areas; the elbows and knees; the antecubital, popliteal, axillary fossae; and the intergluteal region within 12 hours of oral treatment with Amoksina Ò tablet 500 mg (Mustafa Nevzat _ Ilac¸ Sanayii A.S¸., _ Istanbul, Turkey) (Fig. 1A–C). There was no fever, respiratory distress, lymphadenopathy, or other systemic signs or symptoms. The tablet contained amoxicillin trihydrate as the active ingredient and microcrystalline cellulose, magnesium stearate, and sodium starch glycolate as inactive ingredients. The drug was stopped, and the lesions resolved with topical corticosteroids within 1 week, leaving slight postlesional hyperpigmentation. On further history, 2 months before, similar lesions had appeared in the same locations after ingestion of amox- icillin. Histopathology of the right axillary lesion in the subacute phase showed focal parakeratosis, mild acan- thosis, melanophages in the papillary dermis, and mild mononuclear perivascular inflammatory infiltration. Address correspondence to Esen O ¨ zkaya, M.D., _ Istanbul U ¨ niversitesi _ Istanbul Tıp Faku¨ltes, Deri ve Zu¨hrevi Hastalıkları Anabilim Dalı, 34093 _ Istanbul, Turkey, or e-mail: profeo@istanbul. edu.tr. DOI: 10.1111/j.1525-1470.2011.01656.x Ó 2011 Wiley Periodicals, Inc. 711 Pediatric Dermatology Vol. 28 No. 6 711–714, 2011