Primary Paraspinal Intramuscular Hydatid Cysts Mimicking a Soft Tissue Tumor: A Case Report

Abstract Primary intramuscular hydatid disease of the paraspinal muscles is exceptionally rare, particularly in the absence of hepatic or pulmonary involvement. Its nonspecific clinical and radiological features often mimic soft tissue tumors, creating diagnostic challenges for neurosurgeons practicing in endemic regions. A 22-year-old woman presented with a slowly enlarging, mildly painful right lumbar paraspinal mass without animal exposure or systemic symptoms. Magnetic resonance imaging revealed a multiloculated cystic lesion extending from L2 to L4 that lacked definitive hydatid features and could not be clearly distinguished from a synovial cyst, cystic schwannoma, abscess, or epidermoid cyst. Serology showed positive Echinococcus granulosus IgG (ELISA). The patient underwent posterior en bloc excision. Intraoperative management included meticulous containment and irrigation with 3% hypertonic saline and povidone-iodine for approximately 10 minutes, followed by copious saline washout. Gross pathology revealed multiple daughter cysts, and histopathology confirmed a hydatid cyst with laminated and germinal layers. Albendazole (400 mg twice daily) was administered for 3 months. At 8 months of follow-up, the patient remains asymptomatic with no radiological recurrence. Hydatid disease should be considered in the differential diagnosis of paraspinal cystic lesions, even in young patients without exposure history or visceral involvement. Early recognition, intact surgical excision, use of scolicidal agents, and appropriate antiparasitic therapy are critical to preventing recurrence.