Orbital Yolk Sac Tumor in an Infant.

Yolk sac tumors most commonly arise in the gonads, such as the testes or ovaries. Extragonadal yolk sac tumors occur primarily in midline sites, such as the mediastinum, sacrococcygeal area, and retroperitoneum. Orbital yolk sac tumor is an extremely rare disease. Herein, the authors report an unusual case of an orbital yolk sac tumor in an infant. The patient responded very well to chemotherapy. Imaging tests performed after the completion of chemotherapy showed no evidence of disease, and the serum AFP level was normal. In conclusion, distinguishing orbital yolk sac tumors from other orbital lesions, including those of congenital, benign, or malignant origin, is critical for its prompt treatment.