Background: Musculoskeletal hydatidosis is very rare and represents 1%-5.4% of all cases of echinococcosis. On clinical basis, infection mimics a soft-tissue tumor, and the preoperative radiological diagnosis is very important to avoid biopsy.
Case presentation: We report an unusual case of primary subcutaneous hydatidosis in proximity to vastus lateralis muscle. It was diagnosed according to the computed tomography appearance, clinical and pathological findings. A 43 year old female patient was admitted with a history of pain at proximal thigh for the last 30 days. On physical examination, a mass which was 4 x 5 cm in diameter, painful and erythematous, was palpated over greater trochanter. Sedimentation rate was 40 mm in the first hour. CT (Computed Tomography) scan demonstrated, a soft tissue mass with central cystic component in the subcutaneous tissue near vastus lateralis muscle. Histopathological examination of the specimen revealed a pericystic structure, which consisted of connective tissue and scattered hyaline cells showing a necrotic basophilic structure that resembled a cuticular membrane. Treatment with high dose albendazole was conducted for 4 weeks.
Conclusions: This case illustrates that echinococcal disease should be considered in the differential diagnosis of every cystic mass in every anatomic location, especially when they occur in areas where the disease is endemic.