Photo Page: Bazaar, Shahr-e Rey, Iran

Primary hydatidosis of muscle is very rare and can cause a variety of diagnostic problems. Its diagnosis is based on clinical, laboratory and radiological findings. As this infestation resembles a soft tissue tumor on clinical examination, the preoperative radiological diagnosis is very important to avoid unnecessary biopsy. The objective of this article is to present the pathognomonic "Water-lily sign" that has not been previously reported in this muscle group. To the best of our knowledge, our case is the second reported case of this pathognomonic sign in magnetic resonance imaging of primary intramuscular hydatidosis.