Introduction: Germ cell tumors in childhood occur at a rate of 2 to 3 cases per million inhabitants, representing 1 to 2% of malignant solid tumors in the pediatric population, becoming the malignant tumors with the highest incidence in testicles in males and ovaries in females. The second place of presentation of extragonadal germ cell tumors is in the mediastinum with or without infiltration of the lung. One of the main means for diagnosis is the determination of serum markers: Alpha-Fetoprotein (AFP) and Beta fraction of chorionic gonadotropin. Objective: To describe a patient with a malignant tumor of the yolk sac of the lung with bone metastases at debut. Case presentation: White male patient who, at the age of 3 years, began to experience painful urination, constipation, edema of the lower limbs, and gait disorders. In the diagnostic imaging studies, a tumor was detected in the right lung, with metastasis to the Lumbar Spine (L-5) at debut, with elevation of the alpha-fetoprotein tumor marker. A thoracoscopic biopsy was performed and the result was yolk sac tumor with elements of mixed germ cell tumor. Our greatest desire is to make the medical population aware of the infrequent location of this variant of tumor in the lung in pediatric age and the importance of timely diagnosis of the disease.