Anaphylactic Shock Following Spontaneous Rupture of Pulmonary Hydatid Cyst: A Case Report.

We present a case of a 31-year-old rural Iranian man with no prior medical history who developed sudden-onset dyspnea, generalized urticaria, and hypotension. Based on clinical findings and unstable vital signs, anaphylactic shock was suspected and immediate treatment with oxygen, intravenous fluids, and intramuscular epinephrine was initiated. Following stabilization, a spiral chest CT scan revealed a large hydatid cyst with lower lobe collapse, inner membrane detachment near the pericardium, pericardial effusion, and hydropneumothorax. The patient was referred for thoracic surgery, which was successfully performed. He was discharged in stable condition with albendazole therapy and follow-up. Although rare, anaphylactic shock due to hydatid cyst rupture should be considered in endemic regions. In the emergency setting, prompt differentiation from other acute conditions such as asthma, angioedema, or pulmonary embolism is essential to avoid delays in life-saving interventions. Prompt administration of epinephrine and surgical management are essential for favorable outcomes.