Clinical Radiology (2001) 00: 000±000 doi:10.1053/crad.2000.0467, available online at http://www.idealibrary.com on Case Report Cystic Mesenchymal Hamartoma Mimicking Hepatic Hydatid Disease SIMON L. SMITH, NORLISAH M. RAMLI, JOHN M. SOMERS Department of Radiology, Queen's Medical Centre, Nottingham, U.K. Hydatid disease, caused by Echinococcus granulosus, is relatively rare in children. It is often described as having a pathognomonic appearance on ultrasound (US) and computed tomography (CT) [1]. Mesenchymal hamartoma is a rare hepatic developmental abnormality con®ned almost exclusively to children under the age of 2 years. After haemangioma it is considered to be the second commonest benign liver tumour in the paediatric age group, with 140 cases reported up to 1990 [2]. We report a case of cystic mesenchymal hamartoma in a 7-year-old girl which was radiologically indistinguishable from hepatic hydatid disease. CASE REPORT A 7-year-old, previously healthy, girl presented with a 3-week history of increasing abdominal distension and cervical lymphadenopathy. On examination she was pale, lethargic but apyrexial. There was a clinically obvious mass in the right upper quadrant of her abdomen. The abdominal skin showed multiple dilated super®cial veins but no other speci®c abnormalities were found. Initial haematological investigations, including liver function tests and C-reactive protein, were all within normal limits. Abdominal US revealed a 1813 cm cyst in the epigastrium, arising from the liver. It was thin-walled and contained anechoic ¯uid with a few internal septae. Posterior to this structure was a second 10 cm cyst, consisting of a series of smaller `daughter' cysts, some of which contained solid elements (Fig. 1). CT con®rmed the presence of two large hepatic cysts separated by a soft tissue density band. Again the posterior of the two cysts contained multiple intraluminal rounded lesions (Fig. 2). Although there was no relevant history of exposure to the parasite, given the characteristic imaging appearances, a presump- tive diagnosis of hepatic hydatid disease was made. Laparoscopy con®rmed the presence of the two cysts. A 6 French catheter was inserted into the larger of the two lesions at laparoscopy and 100 ml of green ¯uid aspirated. On the basis of the imaging and operative ®ndings the patient was started on appropriate chemotherapy for Echinococcus eradication. Initial ELISA serology for Echinococcus was negative. Alpha±feto protein and b-HCG were all normal. Serum IgE was elevated, but otherwise the immunoglobulin pro®le was normal. 0009-9260/01/000000+00 $35.00/0 # 2001 The Royal College of Radiologists Fig. 2 ± CT of the upper abdomen showing a massive septated cavity in the liver with posterior ®lling defects (arrows). Fig. 1 ± US of the liver showing a large hypo-echoic cavity containing multiple `daughter cysts' (arrows). Author for correspondence and guarantor: Dr S.L. Smith, Depart- ment of Radiology, Queen's Medical Centre, Nottingham NG7 2UH, U.K. Fax: 44 (0) 115 9709962; E-mail: simonsmith@ukonline.co.uk