Behind the Knife ABSITE Review 2026: Thoracic Surgery

Thoracic Anatomy and Physiology

• 🧠 The right lung has three lobes, while the left lung has two.
• 🗺️ Lymph node stations are remembered by single digits for mediastinal and double digits for hilar/lung.
• 💧 The thoracic duct originates at L2, crosses at T5 from right to left, and empties into the left internal jugular and subclavian veins.
• 🐦 The azygos vein drains into the superior vena cava.
• ⚡ The phrenic nerve runs anterior to the hilum, while the vagus nerve runs posterior.
• 💨 Type II pneumocytes are responsible for producing surfactant, a key component of which is phosphatidylcholine.
• 🕳️ Pores of Kohn allow direct air exchange between alveoli, analogous to the Space of Disse in the liver.

Pulmonary Function and Pleural Effusions

• 🫁 For a lobectomy, pre-operative FEV1 or DLCO should be >80%, with a post-operative predictive FEV1/DLCO >40%. A V/Q scan is used for marginal cases.
• 💧 Light's criteria for exudative pleural effusions include a pleural to serum protein ratio >0.5, pleural to serum LDH ratio >0.6, or pleural LDH >2/3 of normal serum LDH.
• 🦠 Causes of pleural effusions/empyema include increased capillary permeability (sepsis, malignancy, pancreatitis), increased hydrostatic pressure (CHF, CKD), and hypoalbuminemia (cirrhosis, nephrotic syndrome).
• 📈 Imaging for pleural effusions shows blunting of the costophrenic angle on X-ray (visible >300ml), fluid with loss of inspiratory sliding on ultrasound, and heterogeneous/loculated appearance for empyema on CT.
• 💊 Treatment for pleural effusion is conservative, addressing the underlying cause, unless symptomatic (then consider drainage). Empyema requires antibiotics, drainage, and potentially decortication.
• 🩸 Retained hemothorax is managed with a chest tube, followed by VATS or thoracotomy if it fails.

Chylothorax, Pneumothorax, and Lung Abscesses

• 🥛 Chylothorax is diagnosed by milky fluid with high triglycerides and lymphocyte predominance; common causes are malignancy, trauma, or iatrogenic injury. Management involves a low-fat diet, bowel rest with TPN, chest tube, and potentially octreotide. Surgical ligation of the thoracic duct or talc pleurodesis may be needed if conservative measures fail.
• 💨 Primary spontaneous pneumothorax is treated with observation for small cases or a small gauge chest tube/pigtail catheter for larger or symptomatic ones. Recurrent cases or high-risk professions may require VATS with bullectomy and pleurodesis.
• ⚠️ Tension pneumothorax is a medical emergency requiring immediate needle decompression followed by chest tube placement.
• 🦠 Lung abscesses are typically caused by aspiration or poor dental hygiene and are treated with IV antibiotics. Surgical drainage is considered if the abscess persists for >2 months, is >4 cm, or is thick-walled.

Mediastinal Masses and Superior Vena Cava Syndrome

• 🦠 The most common cause of mediastinal adenopathy is lymphoma.
• 🌳 Neurogenic tumors are the most common mediastinal tumors in both adults and children, located in the posterior mediastinum.
• 🅰️ Anterior mediastinal masses include thymoma, teratoma, ectopic thyroid, and lymphoma, with thymoma being the most common.
• 🥚 Teratomas are the most common germ cell tumor and are found in the anterior mediastinum.
• 🤝 Thymomas are associated with myasthenia gravis (50% of thymomas have MG, 10% of MG patients have thymomas). Thymectomy improves symptoms in 80% of MG patients.
• 🚨 Superior Vena Cava (SVC) syndrome is most commonly caused by malignancy (small cell lung cancer, lymphoma). Non-malignant causes include indwelling devices, fibrosing mediastinitis, and goiters. Symptoms include facial/arm swelling and venous dilation. Diagnosis involves CT with contrast; treatment includes positioning, steroids, and emergent radiation for symptomatic cancer-related cases.

Lung Masses and Cancer

• 🚬 Lung cancer screening involves annual low-dose CT for individuals aged 50-80 with a ≥20 pack-year smoking history who currently smoke or quit within 15 years.
• 📈 Nodal involvement is the strongest prognostic indicator for lung cancer.
• 🧠 Lung cancer commonly metastasizes to the brain, supraclavicular nodes, contralateral lung, bone, liver, and adrenal glands.
• 🔍 Workup for a solitary pulmonary nodule includes reviewing previous imaging for stability or calcification. Growing nodules in surgical candidates may require serial CTs, PET-CT, biopsy, or VATS resection based on risk stratification.
• 📈 Non-small cell lung cancer accounts for about 80% of lung cancers. Squamous cell and small cell are typically central, while adenocarcinoma is peripheral.
• 🦴 Squamous cell carcinoma is associated with paraneoplastic hypercalcemia due to PTH-related peptide. Small cell lung cancer is associated with paraneoplastic syndromes like SIADH and ACTH secretion.
• 🎯 TNM staging for lung cancer is complex; key points include T1-T4 based on size/invasion, N3 for supraclavicular/cervical nodes, and M1 for metastasis (brain, adrenals, etc.).
• 🏥 Treatment for early-stage lung cancer (Stage I-II) is resection or definitive radiation. Locally advanced (Stage III) may involve neoadjuvant chemo-radiation followed by resection. Stage IIIB with T4 or N3 requires chemo-radiation. Stage IV is treated with palliative resection or radiation.
• 🐍 Pancoast tumors invading the thoracic inlet can cause Horner's syndrome or SVC syndrome and are treated with chemo-radiation followed by resection.
• 🫁 Bronchogenic cysts are typically posterior to the carina and usually require resection, unlike asymptomatic pericardial cysts found at the right costophrenic angle.
• 🌟 The most common benign lung tumor in adults is hamartoma, characterized by popcorn calcifications on X-ray. The most common malignant lung tumor is squamous cell carcinoma.
• 🧒 In children, the most common lung tumor is hemangioma (benign), and carcinoid is the most common malignant type.
• 🦠 Bronchioloalveolar carcinoma can mimic pneumonia and grows along alveolar walls.
• 🩹 Post-pneumonectomy syndrome can be managed with tissue expanders.
• ❤️ The internal mammary artery (IMA) has the best patency rate for CABG.