Hydatid cyst of paravertebral muscle mimicking disc herniation.

STUDY DESIGN: Case report. OBJECTIVE: To present a case of primary hydatid cyst in the lumbar subcutaneous tissue affecting posterior paravertebral muscle and mimicking disc herniation. SUMMARY OF BACKGROUND DATA: Cystic hydatid disease is a rare but significant parasitic disease in endemic areas. Musculoskeletal or soft tissue hydatidosis accounts for about 0.5% to 5% of all echinococcal infections in endemic areas and is almost secondary to the hepatic or pulmonary disease. Primary lumbar subcutaneous hydatid cyst affecting paravertebral muscle and extending to neural foramina is a very rare condition even in endemic areas. METHODS: A 25-year-old-female patient was admitted with swelling and pain in the right lumbar region for 3 months. The pain was reflecting in the right gluteal region and the right leg. Lumbar extension and right lateral flexion was painful and straight leg raising test was positive at right side. There was a mild hypoesthesia at L5 dermatome. According to the magnetic resonance image that the clinician obtained for initial diagnosis of lumbar disc herniation, we found multi-cystic masses located at the right paravertebral muscle at the level of L3-L5 which extended to L4-L5 neural foramina and at subcutaneous tissue at the right gluteal region. RESULTS: The patient was operated for the purpose of removal of cysts. Postoperatively, diagnosis of hydatid cyst was confirmed by histopathology. CONCLUSION: By this case, we emphasize that cystic hydatid disease should be taken into consideration in the differential diagnosis of low back pain and could mimic disc herniation. LEVEL OF EVIDENCE: N/A.