In this chapter, common surgical diseases and disorders of the lung, tracheobronchial tree, and pleura are discussed. An important key point is to understand the scope of the "silent epidemic" of smoking-related deaths from lung cancer, as it is the leading cause of cancer-related deaths for both men and women in North America, killing more people annually than breast, prostate, and colorectal cancer combined. The reader should ponder why more societal and governmental efforts are not directed at combating the main cause of this lethal disease, namely, tobacco products.
ANATOMY
The lungs are divided into three lobes with 10 segments on the right and two lobes with nine segments on the left (Fig. 18-1). The decreased number of divisions on the left can be thought of as space taken up by the heart. The right mainstem bronchus forms a gentler curve with the trachea than does the left mainstem bronchus (Fig. 18-2). Therefore, aspirated foreign bodies are more likely to lodge in the right mainstem bronchus. In aspiration pneumonia, the aspirated material is most likely to deposit in the most depen-dent portions of the lungs. For a supine individual, these are the posterior segments of the upper lobes and the superior segments of the lower lobes. The arterial supply to the lungs is through the pulmonary arteries as well as the bronchial arteries, which arise from the aorta and intercostal vessels.
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Figure 18-1 • Lung lobes. Anterior view. From Anatomical Chart Company. |
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Figure 18-2 • Transverse section of the trachea and the esophagus and trachea (anterior views). From Premkumar K. The Massage Connection Anatomy and Physiology. Baltimore, MD: Lippincott Williams & Wilkins, 2004. |
BENIGN TUMORS OF THE TRACHEA AND BRONCHI
PATHOLOGY
Types of benign tumors include squamous papilloma, angioma, fibroma, leiomyoma, and chondroma. Squamous papillomatosis is associated with human papilloma viruses 6 and 11.
EPIDEMIOLOGY
Truly benign neoplasms of the trachea and bronchi are rare.
HISTORY
Patients commonly present with recurrent pneumonias, cough, or hemoptysis.
PHYSICAL EXAMINATION
Patients may have decreased breath sounds on the affected side, with the additional signs and symptoms owing to postobstructive pneumonia.
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DIAGNOSTIC EVALUATION
Chest radiography may demonstrate a mass, and there is often a postobstructive pneumonia if the lesion significantly narrows the bronchial lumen.
TREATMENT
Angiomas frequently regress, and observation is recommended. Other lesions require surgical removal to relieve symptoms and establish a diagnosis. This may require partial lung resection or sleeve resection, where a segment of bronchus is removed and pri-marily reanastomosed. Squamous papillomatosis has a high recurrence rate.
TRACHEOBRONCHIAL TUMORS WITH MALIGNANT POTENTIAL
Tumors with malignant potential include bronchial carcinoids, adenoid cystic carcinoma, and mucoepidermoid tumors. Carcinoid tumors, which are malignant in approximately 10% of patients, may cause paraneoplastic syndromes through release of various substances, including histamine, serotonin, vasoactive intestinal peptide, gastrin, growth hormone, insulin, glucagon, and catecholamines.
EPIDEMIOLOGY
These tumors make up fewer than 5% of all pulmonary neoplasms and have no obvious age or sex predilection. Carcinoids make up approximately 1% of all lung tumors; adenoid cystic carcinoma, approximately 0.5%; and mucoepidermoid, approximately 0.2%.
HISTORY
Patients most commonly complain of cough, dyspnea, hemoptysis, or recurrent pneumonia. Less frequently, carcinoid tumors may produce carcinoid syndrome, with complaints of flushing and diarrhea, as well as manifestations of specific hormone excess. This syndrome only occurs in approximately 3% of patients with carcinoid tumors.
PHYSICAL EXAMINATION
The patient may have respiratory compromise or decreased breath sounds. Carcinoid tumors may cause valvular heart disease with signs of pulmonic stenosis or tricuspid regurgitation.
DIAGNOSTIC EVALUATION
Chest radiography may reveal a lesion or postobstructive pneumonia. Bronchoscopy is useful to obtain tissue diagnosis and define bronchial anatomy. Computed tomography (CT) of the chest is routine for preoperative planning.
TREATMENT
These tumors should all be resected. Long-term survival for carcinoid tumors is 80%; for adenoid cystic carcinoma and mucoepidermoid tumors, the prognosis is also favorable.
LUNG CANCER
EPIDEMIOLOGY
Lung cancer is the leading cause of cancer-related death for both men and women in North America, responsible for >150,000 deaths each year in the United States and accounting for almost 30% of all cancer-related deaths. More than 80% of lung cancers are smoking-related (Fig. 18-3). In the United States, more people die each year from lung cancer than from breast, prostrate, and colorectal cancers combined. Lung cancer kills more men than prostate cancer and more women
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than breast cancer. Lung cancer incidence rates among women continue to increase. Deaths from lung cancer in women have increased 400% between 1960 and 1990. Smoking cessation significantly reduces an individual's risk of developing lung cancer, although the level of risk remains greater than for nonsmokers. Asbestos, formaldehyde, radon gas, arsenic, uranium, chromates, and nickel have been identified as carcinogens, especially when combined with smoking.
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Figure 18-3 • Death rate from lung cancer among smokers and nonsmokers. Nonsmokers exhibit a small, linear increase in the death rate from lung cancer from the age of 50 years onwards. By contrast, those who smoke more than one pack per day show an exponential increase in the annual death rate from lung cancer starting at approximately age 35 years. By age 70, heavy smokers have an approximately 20-fold greater death rate from lung cancer than nonsmokers. From Rubin E, Farber JL. Pathology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins, 1999. |
PATHOLOGY
Lung cancer is divided into small-cell lung cancer (SCLC; 20% to 25%) and non–small-cell lung cancer (NSCLC; 75% to 80%). NSCLC is further divided into squamous cell carcinoma (30%), adenocarcinoma (35%), and large-cell carcinoma (10%). SCLC is usually centrally located and may be associated with paraneoplastic syndromes. Approximately 5% of patients have symptoms of inappropriate secretion of antidiuretic hormone, whereas 3% to 5% have Cushing's syndrome from adrenocorticotropin production. Squamous cell cancer usually occurs centrally and can be associated with symptoms of hypercalcemia secondary to production of a substance similar to parathyroid hormone. Adenocarcinoma typically occurs at the periphery.
HISTORY
Most patients come to seek medical attention as a result of signs and symptoms indicating advanced disease. Ninety percent of patients with lung cancer are symptomatic at the time of diagnosis. Worsening cough with increased sputum production and hemoptysis often indicates airway obstruction by tumor. A history of recurrent pneumonia requiring antibiotic therapy is common. Persistent chest, back, or shoulder pain is related to nerve involvement or direct tumor invasion. Bone pain indicates distant skeletal metastases, whereas neurologic symptoms indicate brain metastases. Systemic symptoms include fatigue, loss of appetite, and unintentional weight loss.
PHYSICAL EXAMINATION
Chest auscultation may reveal diminished breath sounds owing to pneumonia or malignant pleural effusion. Supraclavicular lymphadenopathy may be present. Recent onset of hoarseness indicates involvement of the recurrent laryngeal nerve. Horner syndrome (ptosis, myosis, and anhydrosis) results from a superior sulcus tumor causing neural invasion. Superior vena cava syndrome and Pancoast syndrome (shoulder and arm pain on the affected side) may occur. Paralysis of the diaphragm indicates phrenic nerve involvement. Patients with advanced disease are usually ill-appearing and exhibit significant weight loss.
DIAGNOSTIC EVALUATION
Chest x-ray is often the modality first used to diagnose a malignant pulmonary lesion. Chest CT including the liver and adrenal glands often follows to delineate tumor size, presence of lymphadenopathy and pleural effusion, and evidence of the likelihood of distant disease (Fig. 18-4).
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Figure 18-4 • Solitary pulmonary nodule evaluated by computed tomography (CT). A. Chest radiograph shows nodule in the left upper lobe (arrow). B. CT shows extensive emphysema and a noncalcified nodule in the posterior segment, left upper lobe, with a "tail" extending to the pleura. The nodule is noncalcified and was proven to be a non–small-cell lung cancer. From Crapo JD, Glassroth JL, Karlinsky JB, et al. Baum's Textbook of Pulmonary Diseases. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2004. |
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Bone scan and brain imaging may also be obtained, if necessary. Noninvasive functional testing for distant disease can be conducted via positron emission tomography scan. This information allows for clinical staging and decision making.
Invasive testing is usually required for definitive diagnosis. Diagnostic thoracentesis is used to evaluate for malignant pleural effusion. Flexible bronchoscopy allows for tissue biopsy and bronchial washings. Trans-thoracic CT-guided fine-needle biopsy can also provide diagnostic tissue sampling. Mediastinoscopy with lymph node biopsy can be diagnostic while also providing information for accurate nodal staging (Fig. 18-5).
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Figure 18-5 • Mediastinoscopy. The passive angle of the mediastinoscope within the pretracheal fascia aims the tip of the scope directly at the trachea or subcarinal space. From Shields TW, LoCicero J III, Ponn RB, et al. General Thoracic Surgery. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2004. |
STAGING
The TNM system is used for staging of lung cancer (Tables 18-1 and 18-2). T1 lesions are <3 cm; T2 lesions are >3 cm or involve the main bronchus >2 cm from the carina or involve the visceral pleura. T3 lesions invade the chest wall, diaphragm, mediastinal pleura, or pericardium or involve the main bronchus within 2 cm of the carina. T4 lesions invade the heart, great vessels, mediastinum, trachea, esophagus, vertebral bodies, or carina or have malignant effusions or satellite tumors.
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TABLE 18-1 Current International Staging System for Non–Small-Cell Lung Cancer Staging |
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TABLE 18-2 Lung Cancer Staging |
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N1 lesions have positive nodes in the ipsilateral peribronchial or hilar region. N2 lesions have positive nodes in the ipsilateral mediastinal or subcarinal region. N3 lesions have metastases either to contralateral nodes or ipsilateral scalene or supraclavicular regions.
Stage IA lesions are T1N0M0 lesions. Stage IB lesions are T2N0M0 lesions. Stage IIA lesions are T1N1M0 lesions. Stage IIB lesions are T2N1M0 or T3N0M0 lesions. Stage IIIA lesions are T3N1M0, T1N2M0, T2N2M0, or T3N2M0 lesions. Stage IIIB lesions are tumors without distant metastases, including primary tumors to T4 and N3 regional lymph node metastases. Stage IV patients have evidence of distant metastases.
TREATMENT
Since the first successful pneumonectomy for lung cancer in 1933, surgical resection has been considered the standard therapy for patients with potentially curable disease. For patients with NSCLC, those with clinical stage I and II disease are referred for an attempt at curative surgical resection. For patients with stage III disease, some may be considered for resection as part of a multimodality therapeutic program usually involving neoadjuvant chemoradiotherapy. Patients with N3 disease and clinical stage IV are not typically candidates for surgical resection.
Standard surgical treatment of NSCLC consists of complete resection of the disease. In addition to parenchymal resection, the operation should also include either sampling or removal of all intrathoracic ipsilateral lymph node stations into which the tumor could potentially drain. For tumors confined to a single lung lobe, the most common surgical procedure performed is lobectomy. For tumors invading an adjacent lobe, a bilobectomy is required. If complete resection requires removal of all lobes on the effected side, then pneumonectomy is performed. For a patient with poor pulmonary function and limited pulmonary reserve, then segmentectomy or wedge resection may be performed. However, the decision to perform a smaller resection provides poorer overall survival because studies show higher locoregional recurrence rates after segmentectomy versus the more oncologically complete lobectomy (23% versus 5%).
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Results of clinical trials now support the use of adjuvant platinum-based chemotherapy in patients with completely resected lung cancer (stage I, II, and IIIA). The use of adjuvant chemotherapy improves 5-year survival rates by approximately 5% to 15% when compared with surgical therapy alone. Standard chemotherapy regimens for NSCLC include a platinum agent (cisplatin or carboplatin) combined with a nonplatinum agent (etoposide, irinotecan, paclitaxel, gemcitabine, and others). Radiotherapy is often added if mediastinal lymph nodes are involved (stage III).
As opposed to NSCLC, SCLC is usually widely disseminated at the time of diagnosis, so surgery is rarely indicated. Only very early-stage small-cell tumors (T1 to T2, N0) are considered for potential resection. The standard treatment for this aggressive disease is combined chemotherapy and radiotherapy. Chemotherapy usually consists of combination therapy (including cyclophosphamide, doxorubicin, vincristine, cisplatin, carboplatin, or etoposide), with triplet combinations often used. Radiation therapy, usually in combination with chemotherapy, is an important modality for treating SCLC. Various radiation treatment plans exist, with differing doses, timing, and fractionation schedules. Elective whole-brain irradiation is used in many centers to minimize the risk of developing brain metastases. The principle of brain irradiation is to destroy any hidden tumor cells that may potentially lurk in the brain, because asymptomatic cerebral metastases are theoretically protected from systemic chemotherapy by the blood-brain barrier. By undergoing so-called prophylactic cranial irradiation, it is argued that survival rates are increased and symptomatic metastases are prevented, because approximately 25% to 50% of untreated patients will develop brain metastases.
PROGNOSIS
Lung cancer remains a lethal disease, despite recent advances. The 5-year survival rate for all patients is slightly >10%. For early-stage asymptomatic NSCLC (stage IA), usually detected incidentally on chest radiograph, the 5-year survival rate is approximately 80%. This figure rapidly decreases to 55% for stage IB and to 30% for stage II disease. Given the overall poor survival rates, there has been a resurgence of interest in screening tests using spiral CT scans for early detection of lung cancer. This is an active area of ongoing research. Long-term survival in SCLC is rare.
MESOTHELIOMA
PATHOLOGY
Mesothelioma is a malignant lesion derived most commonly from the visceral pleura.
EPIDEMIOLOGY
Mesothelioma is rare. Asbestos is the major risk factor. Cigarette smoking markedly increases the incidence of mesothelioma in patients exposed to asbestos.
HISTORY
Chest pain from local chest wall extension, dyspnea secondary to pleural effusion, and lung entrapment, weight loss, and unexplained night sweats may occur.
PHYSICAL EXAMINATION
The patient may have decreased breath sounds on the side of the tumor as a result of pleural effusion and lung entrapment.
DIAGNOSTIC EVALUATION
Chest radiography often demonstrates a pleural effusion. Thoracocentesis typically yields bloody fluid, and cytology is often negative for malignant disease. CT scan shows a chronic effusion with irregular thickened visceral pleura. Patients with a suggestive history and a recurrent pleural effusion with no clear cause should undergo thoracoscopy and pleural biopsy, even in the presence of negative fluid cytology.
TREATMENT
Overall prognosis is poor, with few survivors living beyond 2 years. Early-stage lesions may be resectable but require induction chemotherapy followed by extrapleural pneumonectomy, a significantly morbid procedure. Chemotherapy and radiotherapy are used for nonoperative patients.
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PNEUMOTHORAX
The lung is covered by visceral pleura, and the inner chest wall is covered by parietal pleura. These two continuous surfaces form a potential space. Simple pneumothorax occurs when air enters this space and the lung falls away from the chest wall resulting in a "dropped" lung (Fig. 18-6). Open pneumothorax occurs when a defect in the chest wall allows continuous entry of air from the outside (Fig. 18-7). Tension pneumothorax occurs when air enters the potential space but cannot escape. A ball valve–like effect
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allows pressure to increase within the hemithorax, thereby forcibly collapsing the ipsilateral lung and compressing mediastinal structures.
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Figure 18-6 • Pneumothorax. Injury to lung tissue allows air to leak into the pleural space and put pressure on the lung. From Cohen BJ. Medical Terminology. 4th ed. Baltimore, MD: Lippincott Williams & Wilkins, 2003. |
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Figure 18-7 • Open pneumothorax with element of tension causing midline shift of mediastinal structures. From Willis MC. Medical Terminology: A Programmed Learning Approach to the Language of Health Care. Baltimore, MD: Lippincott Williams & Wilkins, 2002. |
ETIOLOGY
Spontaneous pneumothorax is usual seen in young thin males with rupture of congenital apical blebs or in older patients with bullous emphysema from smoking. It can also occur in patients on mechanical ventilation, especially if high inspiratory pressures are required. Infection, specifically tuberculosis or Pneumocystis carinii, can cause pneumothorax, as can lung tumors on rare occasion. Placement of central venous catheters results in pneumothorax in 1% of cases. The use of ultrasound guidance for central line placement in the internal jugular position reduces the chance of pneumothorax to nearly zero. Thoracocentesis, needle biopsy, and operative trauma are other iatrogenic causes. Open pneumothorax is caused by penetrating trauma, whereas tension pneumothorax can occur by any of the above mechanisms.
HISTORY
Patients can be entirely asymptomatic, or they may complain of dyspnea or pleuritic chest pain.
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PHYSICAL EXAMINATION
Simple pneumothorax may result in decreased breath sounds and hyperresonance on the affected side. Tension pneumothorax may cause tachycardia, hypotension, and hypoxia, and the trachea may be displaced away from the affected side.
DIAGNOSTIC EVALUATION
Chest radiography reveals absence of lung markings in the affected area, usually in the apex, in an upright film. A visible line corresponding to the visceral pleural surface of the lung is evident. Tracheal deviation or mediastinal shift suggests tension pneumothorax.
TREATMENT
Simple pneumothoraces of less than 20% can be observed if no increase in size is demonstrated on serial chest x-rays and the patient is hemodynamically stable. Indications for chest tube placement include size >20% or those that demonstrate increase in size during serial radiographic observation. Open pneumothorax requires repair of the defect and tube thoracostomy. Symptomatic tension pneumothorax is a surgical emergency and requires immediate needle thoracostomy, usually in the midclavicular line in the second intercostal space on the affected side. This will decompress the chest and allow normalization of hemodynamics and oxygenation. Tube thoracostomy should then follow (Fig. 18-8).
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Figure 18-8 • Tube thoracostomy. A. The site for insertion of the tube at the anterior axillary line. The skin incision is usually made over the intercostal space one below the space to be pierced. B. The various layers of tissue penetrated by the scalpel and later the tube as they pass through the chest wall to enter the pleural cavity (space). The incision through the intercostal space is kept close to the upper border of the rib to avoid injuring the intercostal vessels and nerve. C. The tube advancing superiorly and posteriorly in the pleural space. From Snell RS. Clinical Anatomy. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2003. |
EMPYEMA
Empyema is an infection within the pleural space.
ETIOLOGY
Empyema is most commonly caused by pneumonia, lung abscess, recent thoracic surgery, or esophageal perforation. The most common organisms are those that cause primary lung infection, including Staphylococcus, Streptococcus, Pseudomonas, Klebsiella, Escherichia coli, Proteus, and Bacteroides.
HISTORY
The patient may have a history of previous pneumonia, thoracic surgery, or esophageal instrumentation. Fatigue, lethargy, and shaking chills may occur.
PHYSICAL EXAMINATION
The patient is often systemically ill. Fever and decreased breath sounds at the affected lung base are common.
DIAGNOSTIC EVALUATION
The serum white blood cell count is elevated. Chest radiography reveals a pleural effusion. Chest CT shows a defined fluid collection (Fig. 18-9). Aspiration of the pleural fluid by thoracentesis shows an exudative effusion, characterized by a high white blood cell count with predominantly polymorphonuclear cells, a low pH, a low glucose, and high lactate dehydrogenase. Bacteria on Gram stain and culture may be present.
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Figure 18-9 • Empyema. Air fluid level (arrowhead) in the pleural space in this patient with an empyema and bronchopleural fistula. An elliptical fluid collection is present, and the inner margin of the collection is smooth and thin. The inner margin also appears dense (straight arrows), indicating enhancement, with a split-pleura sign. From Shields TW, LoCicero J III, Ponn RB, et al. General Thoracic Surgery. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2004. |
TREATMENT
On rare occasions, antibiotics and needle aspiration alone are successful, but usually tube thoracostomy is required. For patients who have inadequate re-expansion owing to "trapped" lung after chest tube insertion, surgical decortication may be required to remove the restricting pleural peel and facilitate lung re-expansion.
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KEY POINTS