Alveolar echinococcosis of the spine.

Alveolar echinococcosis (AE) is a rare parasitic disease caused by the larval stage of Echinococcus multilocularis. It differs from cystic echinococcosis caused by Echinococcus granulosus. The main endemic areas of AE are Alaska, Canada, Japan, and parts of Europe. Hepatic involvement invariably occurs, but it is unusual for bone to be affected. We report the case of a woman presenting with a long history of pain, cachexia, morning stiffness, and biological signs of inflammation. Radiographs and principally magnetic resonance images were nonspecific, showing inhomogeneous osteolysis of vertebral bodies without loss of intervertebral disc height but with a paravertebral mass. The diagnosis ultimately relied on pathological examination, which showed an anhistic laminated membrane colored in red with Periodic-Acid-Schiff surrounding a central cavity, and by the serologic testing, principally ELISA Em2(+) method, which allowed a 97% specificity and 99% specificity in the diagnosis of AE. AE involving bone is an uncommon condition. Although magnetic resonance imaging can be used to search for local complications, the features it detects are, like those revealed by radiographs, nonspecific and can lead to AE being misdiagnosed as neoplasm or tuberculous osteitis. When a patient presents with suspected AE in an endemic area, the diagnosis can be achieved by serological testing alone (Western blot and Em2(+) ELISA), thereby avoiding the need for biopsy.