<prompt> During exploration, a patient is found to have a tumor in the thymus that is invading the pericardium and surrounding the left and right phrenic nerves. The pathologist says that appears on frozen section to be a benign thymoma. The surgeon now shouldRepeat frozen sectionAttempt as complete a resection as possibleClose the chest and plan irradiation therapyClose the chest and await permanent sections  <response>: Ans. b. Attempt as complete a resection as possibleThymomas usually appear histologically benign even though they may be grossly invasive.Thymectomies are necessary when a thymoma is present to prevent the spread of malignant thymic disease. 