Thymectomy

Introduction

A thymectomy is a surgery to take out your thymus gland and thymic tumors. Surgical resection of the thymus gland (ie, thymectomy) is used to treat thymic tumors (thymoma, thymic carcinoma, and thymic neuroendocrine [carcinoid] tumors) and for the management of myasthenia gravis.

Anatomy

The thymus is an encapsulated bilobed gland that lies in the anterior mediastinum Each lobe contains both superior and inferior horns and each extends laterally towards the phrenic nerve on each side. This small gland in the lymphatic system makes and trains special white blood cells called T- cells. The T-cells help your immune system fight disease and infection. Thymus gland produces most of your T-cells before birth. The rest are made in childhood and you’ll have all the T- cells need for life by the time you hit puberty.

Indications of thymectomy

Thymectomy is indicated for resection of tumors including thymoma, thymic carcinoma, and thymic neuroendocrine tumors. Thymoma is considered malignant and should be resected even though it generally has an indolent growth pattern.

Signs and symptoms:

o Persistent cough

o Shortness of breath

o Pain or pressure in the chest

o Muscle weakness

o Drooping eyelids

o Double vision

o Arm or facial swelling

o Difficulty swallowing

o Anemia, which is a low red blood cell count

o Frequent infections

o Fatigue

o Dizziness

· Myasthenia gravis is an autoimmune that causes skeletal muscle weakness. These are the muscles that connect to your bones and help you move. Myasthenia gravis usually targets the muscles in your eyes, face, neck, arms and legs – Thymectomy is used to manage thymoma associated with myasthenia gravis and is also a validated treatment for those with myasthenia gravis who do not have thymoma (ie, nonthymomatous myasthenia gravis)

Signs and symptoms:

o drooping eyelids (ptosis)

o blurry or double vision (diplopia)

o facial paralysis

o changes in your facial expressions

o difficulties chewing

o difficulty speaking (dysarthria)

o issues with swallowing

o difficulty swallowing or chewing

o hoarse voice

o neck weakness, which can make it difficult to hold up your head

o shortness of breath

o difficulty breathing

o weakness in the diaphragm and chest muscles

o fatigue

o weakness in your fingers, hands, and arms

o overall weakness in your legs

o problems walking up stairs or lifting objects

Preoperative evaluation and Preparation

All patients being assessed for thymectomy should undergo a thorough history and physical exam. History should include any past history of radiation to the neck or chest, and prior surgery in the neck, mediastinum, or thorax. For patients with an anterior mediastinal mass, differentiating a thymic mass from other anterior mediastinal tumors, including thyroid tumors, germ cell tumors, and lymphoma, requires specific considerations.

On physical examination, the patient should be assessed for adenopathy that would raise suspicion for metastatic disease or lymphoma, as well as any physical characteristics that may suggest a benefit for one surgical approach over another, such as limited ability to extend the neck, which would make a transcervical approach difficult, or chest wall deformity or severe obesity that could complicate port placement

Preoperative imaging evaluation is important to determine the likelihood of resectability of a thymic tumor and whether one should consider induction therapy prior to attempting resection. Thymectomy has traditionally been performed via a median sternotomy, but minimally invasive techniques are increasingly applied, primarily using unilateral or bilateral video or robotic-assisted thoracoscopic techniques.

Confirm resectability and tumor staging — There are no consensus guidelines on determination of unresectability. Preoperative cross-sectional imaging help determine potential resectability, specifically evaluating whether intrathoracic structures are invaded by the tumor. The Masaoka-Koga classification has been the most commonly used and reported staging system for thymic epithelial tumors.

Masaoka stage I and II (corresponding to AJCC stage I/II) tumors are treated with thymectomy.
Masaoka stage III (AJCC stage IIIa) tumors may be treated with thymectomy if judged to be completely resectable by preoperative evaluation. Otherwise, induction chemotherapy followed by surgery can be used.)
Masaoka stage IVa/b (AJCC stage IIIb/IVa/IVb) tumors are generally not considered resectable. They can be considered for resection in selected cases but certainly should be discussed in a multidisciplinary setting.

Biopsy — Preoperative biopsy is not required for patients with small tumors that have no evidence of invasion beyond the thymus and that are radiographically suspicious only for thymoma.

Evaluation for myasthenia gravis — Because of the risks associated with surgery, all patients with thymic tumors, particularly those with thymoma, should be evaluated for evidence of myasthenia gravis; if signs or symptoms are present, these should be treated medically prior to surgery. Important perioperative surgical considerations include the following:

●NO patient in myasthenic crisis is a candidate for surgery. Symptoms must be under control at time of surgery.

●Plasmapheresis may induce coagulation abnormalities by removing coagulation factors and complement components (C3 and C4), which may increase bleeding risk and affect the timing of surgery.

●Ideally, steroid dosages should be minimized to optimize postoperative wound healing, but many will require perioperative stress dosing.

What happens during a thymectomy?

Healthcare providers can perform a thymectomy using open or minimally invasive ways that use cameras and/or robotic arms. Talk with your provider about which approach is best for you.

Transsternal approach

Thymectomy surgery steps include:

Do a sternotomy dividing your breastbone all or part of the way down like open heart surgery).
Remove the thymus and affected nearby tissue through the incision.
Put in one or two chest tubes for drainage.
Close the sternum with wires and close the skin.

Robotic-assisted or VATS (video-assisted thoracic surgery) approach

Thymectomy surgery steps include:

Place three ports or openings (including one for a camera) into your chest from one side.
Use the robot arms or long instruments to separate the thymus (and tumor if present) from the surrounding structures.
If necessary, make mirrored incisions on the opposite side of your chest to complete removing the thymus.
Place all tissue in a bag in the chest and extract it through one of the small incisions made during the surgery.
Place one or two chest tubes for drainage.
Use medication to block nerves in the chest wall to help with postoperative pain.
Remove the ports and close the incisions.

Thymectomy Needs:

1. Identify the approach of the surgery

· Sternotomy approach- Sternotomy Kit- Please see List of OR needs

· VATS approach - VATS Kit- Please see List of OR needs

2. Identify if the surgeon needs Staplers for VATS approach – Please coordinate with the surgeon

Instruments/ Equipments:

1. Identify the approach of the surgery

· Sternotomy approach

¨ Open Heart set

¨ Sternal saw

¨ Light handle

¨ Prep set