Rare Recurrent Hydatid Cysts in Thigh and Pelvis Challenge Diagnosis and Treatment

Musculoskeletal hydatid cysts are caused by Echinococcus granulosus. While the parasite most commonly forms cysts in the liver and lungs, musculoskeletal involvement accounts for less than 3% of all hydatid disease cases. Isolated soft tissue or bone involvement without hepatic or pulmonary cysts is exceedingly uncommon, and most published accounts consist of single cases, which makes accumulated clinical experience scarce.

The patient presented with persistent left thigh pain and progressive difficulty walking. Despite this prolonged treatment, the disease had returned.

Physical examination revealed a firm, tender mass on the anterior aspect of her left thigh. Ultrasound imaging showed a large cystic lesion measuring 9.5 by 13.7 centimeters filled with clear fluid. Computed tomography of the chest, abdomen, and pelvis was then performed to search for disease elsewhere in the body; it found no hepatic or pulmonary cysts but identified an additional cyst in the left pelvic wall, confirming that the infection had spread to a second anatomical site.

Magnetic resonance imaging confirmed multiple cystic lesions ranging from 3 to 13 centimeters in size. The imaging pattern, combined with her surgical history, pointed to recurrent multifocal musculoskeletal hydatidosis, a presentation the authors describe as extremely rare.

Postoperatively, the patient received albendazole at 400 milligrams twice daily.

Histopathological examination of the excised tissue confirmed the diagnosis of hydatid cysts. At a five-month follow-up visit, the patient showed no early recurrence, although the authors emphasize that this represents only short-term follow-up for a disease known to reappear years after treatment.

The case carries several practical lessons. First, the authors argue that multifocal musculoskeletal hydatid cysts should be considered in the differential diagnosis of soft tissue masses even when there is no visceral involvement, because the absence of liver or lung cysts can falsely reassure clinicians. Second, they stress that complete surgical excision without cyst rupture, combined with scolicidal agents and adjunctive albendazole, is essential to prevent recurrence. Third, they recommend long-term follow-up, since recurrent or multifocal disease may emerge years after initial treatment, as it did in this patient six years after her first resection.

As a single case report, the findings describe one patient’s experience rather than a comparison of treatment strategies, and the reported five-month recurrence-free outcome cannot establish long-term efficacy. Nevertheless, the report adds to the limited literature on isolated musculoskeletal hydatidosis and underscores the diagnostic and therapeutic challenges that this rare parasitic disease continues to pose.

Subject of Research: A rare case of recurrent multifocal musculoskeletal hydatid cyst disease involving only the thigh and pelvis, without liver or lung involvement.

Article Title: Diagnostic and therapeutic challenges in multifocal recurrent musculoskeletal hydatid cysts: a case report

Article References: Alnasr, A. A., Janoud, O., Darwish, M., Hodaifa, D., MANSOR, M., & HAMMADIEH, A. (2026). Diagnostic and therapeutic challenges in multifocal recurrent musculoskeletal hydatid cysts: a case report. BMC Musculoskeletal Disorders. https://doi.org/10.1186/s12891-026-10687-2

Image Credits: AI Generated

DOI: 10.1186/s12891-026-10687-2

Keywords: hydatid cyst, Echinococcus granulosus, musculoskeletal hydatidosis, case report, recurrence, albendazole, pericystectomy, scolicidal irrigation, soft tissue mass, pelvic cyst, thigh pain, BMC Musculoskeletal Disorders