Undifferentiated thymic carcinoma with intracranial metastasis in a two-year-old.

Thymic carcinoma with central nervous system involvement is very rare in children. A 27-month-old girl presented with a unilateral squint, vomiting, and behavioral changes. Imaging studies showed a silent anterior mediastinal mass and a large metastatic mass at the base of the skull. Biopsy of the anterior mediastinal mass confirmed an undifferentiated tumor consistent with thymic carcinoma. The child died within 3 months of the onset of symptoms, due to progression of the disease. These lethal tumors of unknown histogeneses and etiology are aggressive in nature, resistant to therapy, and have a rapidly fatal course.