Answer to Photo Quiz (See Page 426)

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ANSWER TO PHOTO QUIZ (SEE PAGE 426)

Diagnosis: Hydatid Bone Disease (Cystic Echinococcosis) Radiographic findings of skeletal involvement in cystic echinococcosis are not specific, and the differential diagnostic is wide. It includes tuberculosis, mycoses, malignant fibrous histiocytoma, myeloma, sarcoma, metastatic disease, aneurysmal bone cyst, and giant cell tumor [1]. However, MRI allows for an interesting differentiation, showing cystic lesions and involvement of the soft tissues [1]. Reprints or correspondence: Professor Philippe Brouqui, Service des Maladies Infectieuses et Tropicales, Hoˆpital Houphoueˆt Boigny, 416 Chemin de la Madrague Ville, 13015 Marseille, France (Philippe.Brouqui@medecine .univ-mrs.fr). Clinical Infectious Diseases 2000; 31:543–4 q 2000 by the Infectious Diseases Society of America. All rights reserved. 1058-4838/2000/3102-0025$03.00

Figure 2. Sagittal T2-weighted MRI of the left arm, showing a multicystic lesion of the humeral shaft, with extensive involvement of the soft tissues through a wide cortical disruption.

In this case, serological tests for hydatid disease (indirect hemagglutination and ELISA) were positive. At the time of surgery, an encapsulated soft-tissue lesion was removed, followed by curettage of the humeral diaphysis, with concomitant irrigation with a hypertonic saline solution. The diagnosis of hydatid bone disease was confirmed by histology. Human hydatid disease is a zoonotic infection caused by the larva of Echinococcus granulosus. Humans are an incidental host of the larva. Infection is acquired by ingesting the egg of the cestode from infected dogs (the definitive host). The adult form of E. granulosus is found in the small intestines of dogs that have ingested sheep, lamb, or beef containing larval cysts [2]. The disease is ubiquitously distributed, with increasing occurrence in sheep-raising areas, including the Mediterranean area, South America, South Africa, and Australia. The prev-

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Figure 1. Anteroposterior radiograph of the left arm, showing multiple cystic osteolytic lesions of the humeral diaphysis, with deformity and thinning of the cortex.

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Acknowledgment We thank Dr. Gladys George for reviewing the manuscript.

Philippe Parola, 1 Denis Mathieu, 2 Michel Panuel, 3 Dominique Poitout, 2 and Philippe Brouqui 1 1

Service des Maladies Infectieuses et Tropicales, Hoˆ pital Houphoueˆ t-Boigny, and 2 Service de Chirurgie Orthope´ dique and 3 Service de Radiologie, Hoˆ pital Nord, Marseille, France

References 1. Merkle EM, Schulte M, Vogel J, et al. Musculoskeletal involvement in cystic echinococcosis: report of 8 cases and review of the literature. AJR Am J Roentgenol 1997; 168:1531–4. 2. Ammann RW, Eckert J. Cestodes: Echinococcus. Gastroenterol Clin North Am 1996; 25:655–89. 3. WHO Informal Working Group on Echinococcosis. Guidelines for treatment of cystic and alveolar echinococcosis in humans. Bull World Health Organ 1996; 74:231–42.

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alence of the disease has increased in Europe and North America because of immigration and tourism [2]. The liver (50%–70%) and lung (20%–30%) are the most frequent sites of hydatid cysts. Bone hydatidosis is unusual and represents ∼1%–4% of cases of hydatidosis in humans [1]. Vertebrae (30%–50%) and the pelvis (15%) are the most common sites of involvement, followed by the long bones, principally the femur, tibia, and humerus. The incubation period of the disease may be 110 years. The most frequent presentations include pain, swelling (as in this case), and pathological fracture. Relapses are frequent in cases of hydatid bone disease, despite surgical intervention. The benzimidazole derivatives (principally albendazole) are currently recommended for administration as adjuvant treatment. However, the duration of the treatment is not clearly established [3]. Albendazole must not be used in pregnancy [3]. We recommended treating this patient—after delivery—with albendazole, administered in 6 1-month courses separated by 14-day intervals [3].

CID 2000;31 (August)