Osseous hydatid disease: A mimic of other skeletal pathologies.

Hydatid disease is still endemic in several regions worldwide including Morocco, and is caused in most cases by the larval form of 2 species of the tapeworm Echinococcus: E. granulosus and E. multilocularis. Primary hydatid disease of the bone without systemic involvement is rare. The disease has a silent clinical evolution until it reaches complicated stages. Complications may include pathological fracture, neural deficit, infection, and fistulization of the abscess. Preoperative diagnosis is based on clinical history, imaging findings, and serological tests, which lack high sensitivity and specificity. Although the interpretation of imaging studies can prove to be very confusing because the bone changes evolve with time, and the nonspecificity of these findings often leads to a mistaken diagnosis. The diagnosis requires a high index of suspicion, especially in patients who reside in or travel to sheep-raising areas where hydatid disease is endemic. A high index of suspicion is necessary for the diagnosis, especially in patients that live in or travel to sheep-raising areas where hydatid disease is endemic. The treatment of choice remains surgical, following the principles of a locally malignant lesion. Chemotherapy (albendazole alone or in combination with praziquantel) is indicated when surgery is not possible or as an adjuvant treatment. The prognosis is often poor. We report the case of a 28-year-old woman with long-standing pain in the left hip joint in which the imaging findings were thought of as being either tuberculous or neoplastic. The result of a CT-guided biopsy concurred with an unexpected diagnosis of a hydatid cyst. This case highlights that in the absence of a high index of suspicion for echinococcal infection, the semblance of imaging findings of hydatid disease in the bone to those of other skeletal pathologies can lead to misinterpretation.