Primary Hydatidosis of the Thigh Involving the Vastus Lateralis Muscle: A Case Report.

Hydatidosis is a parasitic disease caused by the larval stage of Echinococcal tapeworm that is endemic in many regions of the world. The subtle and nonspecific nature of the clinical signs frequently results in a delay in diagnosis. Ultrasonography (USG) is the first modality of choice for the diagnosis followed by magnetic resonance imaging (MRI). The detection of a ruptured membrane, observed as low-signal intensity on all pulse sequences, strongly suggests the diagnosis. We report a rare case of a 39-year-old male who presented with fever, pain, and swelling in the right thigh. On further investigations, he was diagnosed to have primary hydatidosis of the thigh involving the vastus lateralis muscle and subcutaneous tissue. The patient underwent en bloc surgical excision of the mass and histopathology confirmed the diagnosis of intramuscular hydatidosis. Understanding the diverse imaging manifestations of primary intramuscular hydatidosis is imperative for accurate preoperative diagnosis, thereby averting potentially fatal outcomes. Timely intervention is paramount as it mitigates both localized and systemic complications that may arise due to cyst maturation. This underscores the criticality of early therapeutic measures to enhance patient outcomes and diminish associated morbidities.