**Question:** 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 should:

A. Resect the tumor and observe for recurrence.
B. Resect the tumor and observe for recurrence.
C. Resect the tumor and observe for recurrence.
D. Resect the tumor and observe for recurrence.

**Correct Answer:**

**Core Concept:** Thymoma is a tumor that arises from the thymus gland, which is responsible for the development and function of T cells, a type of white blood cell involved in immune response. Thymomas can be malignant (malignant) or benign (non-cancerous).

**Why the Correct Answer is Right:**

In this scenario, the pathologist identifies the tumor as a "benign thymoma" on frozen section examination. This means that the tumor is non-cancerous and does not have the potential to spread to other parts of the body. Given the tumor's local invasion into the pericardium and surrounding phrenic nerves, complete surgical excision (thoracotomy) is necessary to ensure the removal of the entire tumor. Post-operatively, the patient will need close follow-up to monitor for any signs of recurrence, as benign thymomas can still have a potential for recurrence despite being non-cancerous.

**Why Each Wrong Option is Incorrect:**

A. Resecting the tumor without considering its origin and potential for recurrence may lead to incomplete removal, potentially resulting in recurrence and worsening the patient's prognosis.
B. Although the tumor is benign, observing the patient without surgical excision does not address the patient's risk of recurrence.
C. Similar to option A, not performing surgery may lead to incomplete removal and recurrence.
D. Surgery is necessary to remove the tumor and monitor for recurrence, as described above.

**Clinical Pearls:**

1. Thoracic surgeons must consider the potential for recurrence even with a benign thymoma.
2. In this case, a thorough surgical excision is necessary to ensure complete removal of the tumor and minimize the risk of recurrence.