Two asymptomatic paravertebral thoracic masses in a 65-year-old patient with isolated macrocystosis. The largest one measured 8 cm and was surgically resected with a presumptive diagnosis of schwannoma. This thoracic mass was hemorrhagic, encapsulated, and composed of fat and hematopoietic tissue. While extramedullary hematopoietic tumors usually occur in patients with severe chronic hemolytic anemia, our report suggests that such lesions must be considered in the differential diagnosis of posterior mediastinal mass in patients without clinically evident anemia.