Diagnostic pitfalls of spinal echinococcosis

To critically examine and elucidate the diagnostic pitfalls of spinal echinococcosis. SUMMARY OF PATIENTS: From October 1957 to June 2006, 25 consecutive cases drawn from 5721 cases of echinococcosis were collected in the First Affiliated Hospital of Xinjiang Medical University. The selected cases comprised 11 males and 14 females; all were treated with debridement operations. The average age was 28.3 years (15 to 56 y). The average duration of infestation with spinal hydatid disease was 3.2 years (0.5 to 12 y). Nineteen of the 25 cases underwent magnetic resonance imaging (MRI) scanning, which identified 17 out of 19 cases as having hydatid disease. The lesion was located in the cervical vertebrae in 3, the thoracic vertebrae in 11, the lumbar vertebrae in 5, and the sacrum in 6 cases.

Eighteen cases were available for follow up; the period ranging from 0.5 to 15 years with an average of 3.6 years. The Casoni test was performed in 15 cases and was positive in 12 patients (80%). In addition, 4 cases were positive in all of the so-called 8 tests of immunodiagnostic methods. MRI examination was performed in 19 of the 25 cases and 17 of these were diagnosed as having spinal hydatid disease (89.47%). The typical MRI appearance is that of a multilocular cyst and the signal of the parent cyst is similar to that of muscle and higher than that of secondary cyst in the T1Weighted image (WI). The signal of the secondary cyst is similar to water, either located in or overflowing or adjacent to the parent cyst. Both the parent and the secondary cysts showed high signals in the TW1 with either rose or wheel shapes. In the 18 cases, which were reviewed, 11 cases had relapsed (61.11%).

Although x-ray or computed tomography images of spinal echinococcosis are similar to tuberculosis, metastases, giant cell tumors, or cysts of the bone, MRI shows distinctive diagnostic features of spinal hydatid disease. Serologic examinations are important to confirm the correct diagnosis.