The "serpent sign"-A classical sign in a nonclassical location: A case report of breast hydatid cyst.

Hydatid cyst is a rare breast pathology; however, it should be included in the differential diagnosis of any breast mass. The history and imaging findings can sometimes raise suspicion of the hydatid nature of the mass. The presence of certain imaging signs specific to hydatid cysts can further indicate this diagnosis. Nevertheless, the definitive diagnosis remains histological, and the treatment is principally surgical. Herein, we present a case of a 38-year-old female who was found to have the "serpent sign" on ultrasonography, which is pathognomonic for ruptured hydatid cysts, as part of the imaging workup for a left breast lump. This case report underscores the importance of characteristic imaging features such as the "serpent sign" in the diagnosis of hydatid disease, especially in unusual sites like the breast where the index of suspicion is particularly low. Recognition of such signs elicits special pre- and intraoperative precautions to minimize complications like local dissemination and anaphylactic shock.