Liver hydatid cyst represents one of the most frequent localizations of Echinococcus granulosus tapeworm in humans. The disease progresses symptom-free in most patients, due to a slow growth rhythm of the cyst. When it reaches large sizes, the hydatid cyst causes discomfort or pain in the liver bed, low appetite, phenomena of hepatitis or cholangitis. The patients are most often diagnosed with liver hydatid cyst after imagistic investigations (radiological or ultrasound) for symptoms that, most commonly, are not related to a hydatid cyst. We present the case of an 11-year-old girl, with no pathological history, who presented forme fruste symptoms, not acknowledged by her parents, and deceased after an anaphylactic shock caused by the rupture of a liver hydatid cyst.