A 20-year-old man was admitted to our clinic after complaining of right upper abdominal pain and gradually increasing visible upper abdominal lump for a month. His clinical examination revealed remarkable epigastric tenderness and right upper abdominal enlargement. His body temperature was 37.8 °C. On admission, his laboratory findings were as follows: WBC count 7800/mm3, HGB 13.1 g/dl, HTC 39.7%, eosinophils 5% (320/mm3), ESR 58 mm/h, CRP 84 mg/dl(0-5). Liver function tests were within normal range. Ultrasonography of the right upper quadrant revealed a 13 × 13 cm cystic lesion in the liver, surrounded by septated liquid 1 cm in diameter (Figure 1). A CT scan of the liver also revealed a 13 × 13 cm cystic lesion, compressing the inferior vena cava, right kidney and pancreas (Figure 2). A serological test for echinococcus was positive. Thus, the cyst and the septated liquid were diagnosed as hydatid cyst complicated by infection. The patient was treated with albendazole (10 mg/kg/day) for the hydatid cyst, and ciprofloxacin (2 × 500 mg orally) and amoxicillin/clavulanic acid (2 × 1 g orally) for the complicating infection. One week after medical intervention, his body temperature was normal, the CRP level had decreased to 28 mg/dl and ESR to 40 mm/h, and the patient underwent surgery. After surgery, the patient was prescribed albendazole for two months, and ciprofloxacin and amoxicillin/clavulanic acid for one week; during this period, the patient had regular follow-ups, with no recurrence of the hydatid cyst.Figure 2CT scan of the liver revealed a 13 × 13 cm cystic lesion, compressing the inferior vena cava, right kidney and pancreas.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Hydatid cyst is endemic in regions such as South America, the Near East, Southern Europe, Africa and Australia1Sahin D.A. Kusaslan R. Sahin O. Dilek O.N. Huge hydatid cysts that arise from the liver, growing exophytically.Can J Surg. 2007; 50: 301-303PubMed Google Scholar. The liver is the organ most likely to be affected. Although surgery is the treatment of choice for all patients with symptomatic disease, albendazole is given both pre-operatively and postoperatively to soften the cysts and to prevent recurrence after the operation2Mehra B.R. Thawait A.P. Gupta D.O. Narang R.R. Giant abdominal hydatid cyst masquerading as ovarian malignancy.Singapore Med. 2007; 48: e284-e286PubMed Google Scholar. Giant hydatid cysts can cause anaphylactic shock and death upon rupture. It is important to remain aware that trauma might lead to perforation and anaphylaxis in such patients. Conflict of interest: No conflict of interest to declare.