SCIENTIFIC ARTICLE Primary Hydatid Cyst of the Scaphoid: Case Report Mehmet Bulut, MD, H. Bayram Tosun, MD, Bengu Cobanoglu Simsek, MD, Lokman Karakurt, MD Hydatid cyst caused by Echinococcus granulosus is a parasitic disease that can affect different organs. It is difficult to diagnose and has a tendency to recur. Primary bone involvement occurs in 0.5% to 4.0% of all patients with hydatid cysts. We present a 31-year-old woman with a primary hydatid cyst in the left scaphoid. Despite the availability of advanced imaging and laboratory investigation modalities (such as magnetic resonance imaging and serological studies) to make an adequate differential diagnosis of a cystic lesion in our case, intraoperative clinical suspicion led to the diagnosis. This was followed by a successful outcome without recurrence after 12 months. (J Hand Surg 2012;37A:1051–1053. Copyright © 2012 by the American Society for Surgery of the Hand. All rights reserved.) Key words Hydatid cyst, scaphoid, E granulosus, surgical treatment. H YDATID CYST IS a parasitosis caused by Echi- nococcus granulosus and is endemic in the sheep- and cattle-breeding farm areas of the Mediterranean, Asia, North and East Africa, South America, and the Middle East. Hydatid cyst, which has 2 hosts (definitive and intermediate), infects humans either by direct contact or by consumption of contam- inated food. Echinococcus embryos migrate from the intestines to lymph and venules and are located in the liver in 60% to 70% of infected patients. If the embryos bypass the liver and enter the systemic circulation, they can be carried to any organ. 1,2 Although bone hydatid cyst may result from hepatic or pulmonary hydatidosis, it is usually a primary disease of the bone without hepatic or pulmonary involvement. The incidence of bone involvement is 0.5% to 4.0% for all patients with hydatid cysts. Effects on the spine are apparent in 50% of patients with osseous involvement. Osseous cysts develop gradually over a period of 2 to 10 years. 1–3 CASE REPORT A 31-year-old woman presented to our clinic reporting pain that started 1 month prior, after a simple fall on the left wrist. Her history was unremarkable for environmental exposure to parasitic disease. The range of motion in the left wrist was mildly painful and minimally restricted. There was minimal tenderness and swelling in the ana- tomical snuffbox. The radiographic examination revealed a well-demarcated cyst in the proximal pole of the scaph- oid ( Fig. 1). Her magnetic resonance imaging scan con- firmed a bone cyst measuring 10  5 mm in the proximal pole of the scaphoid ( Fig. 2). Whole blood count (includ- ing 1% to 4% of eosinophil count), erythrocyte sedimen- tation rate, and C-reactive protein were all within normal range. We decided to explore the scaphoid owing to wrist pain and risk of fracture with a preliminary diagnosis of simple bone cyst. We used a volar approach under tour- niquet control. We encountered a clear fluid and a white membranous tissue resembling a germinative membrane of hydatid cyst. The cystic area was widely curetted and irrigated with abundant hypertonic solution and povidone- iodine solution. The defect was filled with cancellous allograft. We placed the patient in a short-arm thumb spica cast for 3 weeks. Histopathology examination demonstrated hydatid cyst scolex, which is the head-like part of the tapeworm. There was inflammatory cell infiltration in the sur- rounding fibrous tissue (Fig. 3). Both infectious diseases and general surgery specialists evaluated the patient. Her indirect hemagglutination and enzyme-linked immunosor- bent assay examinations were normal. Chest x-ray and From the Department of Orthopedics and Traumatology, Faculty of Medicine, Dicle University, Diyar- bakir;andtheDepartmentofOrthopedicsandTraumatologyandDepartmentofPathology,Facultyof Medicine, Firat University, Elazig, Turkey. Received for publication August 10, 2011; accepted in revised form February 11, 2012. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article. Corresponding author: Mehmet Bulut, MD, Department of Orthopedics and Traumatology, Fac- ulty of Medicine, Dicle University, 21280 Diyarbakir, Turkey; e-mail: bulmeh@yahoo.com. 0363-5023/12/37A05-0028$36.00/0 doi:10.1016/j.jhsa.2012.02.024 ©  ASSH  Published by Elsevier, Inc. All rights reserved.  1051