A 30-year-old female patient presented with swelling on the anterior aspect of the right thigh for the past 3 months.
Initial ultrasonographic evaluation revealed a large multiloculated cystic lesion involving approximately the upper two-thirds of the anterior aspect of the right thigh.
Further MRI revealed a large multiloculated cystic lesion which appeared hyperintense on T2-weighted images and hypointense on T1-weighted images involving the anterior compartment of the right thigh in the intermuscular plane with internal small daughter cysts. It caused medial displacement of the rectus femoris muscle, lateral displacement of the vastus lateralis muscle, posterior displacement of the vastus medialis muscle. On post-contrast study, there was minimal peripheral rim enhancement.
Muscle hydatid disease is a very rare clinical and radiological diagnosis, because the hydatid has to cross the pulmonary and hepatic barriers with additional hindrance of high level of lactic acid in the muscle tissue that is unfavourable for its survival [1, 2]. Differential diagnosis of hydatid disease should be considered for every soft cystic mass in any anatomical location, especially in endemic areas. Hydatid disease of the skeletal tissue presents as large asymptomatic swelling which is fixed to the muscle, most commonly, in the thigh. The swelling being cystic in nature, can be uniloculated or multiloculated with multiple daughter cysts. Ultrasonography, MRI and CT reveal uniloculated or multiloculated cyst. The sensitivity of ultrasonography is 95% and if vesicular fibrils are present, the sensitivity of US increases to 100% [3]. Free floating membrane and multiple smaller daughter cysts maybe seen in it. MRI is reported to be the best for clear identification of involved structures and for surgical planning [4, 5]. MRI is capable of adequately demonstrating most features of hydatid disease, with the exception of calcification which is usually seen in a CT scan [6]. Eosinophilia due to parasitic infestation may or may not be present. Multiloculated lesion with internal daughter cysts is characteristically seen in hydatid disease [8]. Post-contrast peripheral rim enhancement can be seen in hydatid disease [8].
Other differentials with similar presentation include vascular malformation (cystic lesions showing avid contrast enhancement), haematoma (heterogeneous collection with variable internal signal depending on the age of the haematoma), abscess (heterogeneous collection with surrounding inflammatory changes) or myxoid tumours (which appear heterogeneous due to myxoid and solid components) [8]. Surgical excision (pericystectomy) is the treatment of choice in musculoskeletal hydatid disease [9]. Percutaneous aspiration and infusion of scolicidal agents may be considered in inoperable cases [9]. Adjuvant anti-helminthics are used in surgical treatment protocol to prevent dissemination and recurrence [9]. In our case, based on the imaging and clinical diagnosis of hydatid cyst, surgical excision was done, imaging findings of cyst including cyst being in inter-muscular plane were confirmed and cut section of cystic lesion showed multiple yellowish-white daughter cysts confirming hydatid disease. Adjuvant anti-helminthics were administered preoperatively.
Teaching point:
Considering the typical imaging findings of hydatid disease along with the clinical history, though rare, diagnosis of hydatid disease is quite straightforward.
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Hydatid disease of thigh
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According to the provided ultrasound and MRI images, a cystic lesion can be observed in the soft tissue of the anterior aspect of the right thigh. The lesion appears as a multi-chambered cystic structure, with multiple septations and a "cyst-in-cyst" pattern. On T2-weighted MRI, there are areas of uneven high and low signal, and multiple small cysts are visible within some regions, with mild peripheral enhancement. The lesion is located in the intermuscular space, showing expansive growth and a relatively clear boundary.
From the surgical specimen images, a near-oval or lobulated large cystic mass is also seen, with multiple small cysts (“daughter cysts”) on the cut surface, corresponding to the multi-chambered cystic structures identified in the imaging.
Based on the multi-chambered cystic nature, the presence of multiple daughter cysts, and potential local or epidemiological background, muscular hydatid disease is highly suspected.
Considering the patient’s age, clinical presentation (gradually enlarging, painless swelling of the thigh), the multi-chambered cysticChanges revealed by imaging, and the surgical specimen showing multiple yellowish-white “daughter cysts,” the most likely final diagnosis is:
Muscular Echinococcosis (Muscular Hydatid Disease)
Treatment Strategy:
Rehabilitation/Exercise Prescription Recommendations (FITT-VP Principle):
Throughout the rehabilitation process, closely monitor the surgical site and surrounding area to prevent infection or wound breakdown. Patients with compromised cardiopulmonary function or lower physical fitness may require reduced intensity, and rehabilitation training should be conducted under the guidance of a physician or physical therapist.
This report is only a reference analysis based on the supplied clinical and imaging information and cannot replace a diagnosis or in-person consultation with a qualified healthcare professional. If you have any questions or if your condition changes, please consult a specialist or seek further evaluation and treatment at a hospital.
Hydatid disease of thigh
