9. Carcinoma of the lung

Question 1

Definition of lung carcinoma

Answer 1

Malignant epithelial cell tumours of the lung; other neoplasms of the lung (not discussed here) include soft tissue tumours, carcinoid tumours & secondary (metastatic) tumours)

Question 2

Epidemiology of lung carcinoma

Answer 2

1. Most common cause of cancer deaths worldwide
2. Predominantly in men & increasing in frequency amongst women
3. Risk factors:
   - Majority of lung cancers are a consequence of cigarette smoking
   - Other occupational & environmental factors (radioactive material, asbestos, nickel, chromium)

Question 3

Classification of Carcinomas of the Lung

Answer 3

1. Non-small cell lung carcinoma (Less frequently metastatic, less responsive to chemotherapy)
   - Squamous cell carcinoma
   - Adenocarcinoma
   - Bronchioloalveolar carcinoma
   - Large cell anaplastic carcinoma
2. Small cell lung carcinoma (Almost always metastatic, high initial response to chemotherapy)
   - Small cell carcinoma (oat cell carcinoma)

Question 4

Routes of spread & metastasis of lung carcinoma

Answer 4

1. Local spread to adjacent lung parenchyma
2. Lymphatic spread to regional lymph nodes
3. Transcoelomic spread to pleural space, pericardium
4. Haematogenous spread to distant organs (brain,
   bone, liver, adrenal glands etc)

Question 5

Local effects of lung carcinoma

Answer 5

1. Tumour ulceration → hemoptysis
2. Tumour obstruction of airway → pneumonia, lung
   abscess, lobar collapse
3. Tumour obstruction with accumulation of cellular
   lipid in foamy macrophages → lipid pneumonia
4. Tumour spread into pleura → pleural effusion
5. Recurrent laryngeal nerve invasion → hoarseness
6. Esophageal invasion → dysphagia
7. Phrenic nerve invasion → diaphragm paralysis
8. Chest wall invasion → rib destruction
9. SVC compression → SVC syndrome
10. Sympathetic ganglia invasion, especially by Pancoast tumours → Horner’s syndrome
11. Pericardial involvement → pericarditis, tamponade

Question 6

Paraneoplastic syndromes of lung carcinoma

Answer 6

1. Syndrome of inappropriate ADH secretion (ADH)
2. Cushing syndrome (ACTH)
3. Hypercalcemia (PTHrP)
4. Cerebellar degeneration (tumour toxic products)
5. Peripheral sensory & motor neuropathy
6. Proximal myopathy & dermatomyositis
7. Hypertrophic pulmonary osteoarthropathy/clubbing

Question 7

Prognosis of lung carcinoma

Answer 7

1. Poor prognosis (especially small cell carcinoma &
   late stages of the other carcinomas)
2. Overall 5-year survival rate = 5-15%

Question 8

Associations of squamous cell carcinoma

Answer 8

1. Commonest in males
2. Closely correlated to a history of smoking
3. Often preceded by squamous metaplasia (following squamous metaplasia → dysplasia → carcinoma in-situ progression)

Question 9

Gross appearance of squamous cell carcinoma

Answer 9

1. Hilar/perihilar masses (originating from segmental or subsegmental bronchi)
2. Large in size (rapid-growing)
3. Central necrosis & cavitation
4. Locally invasive

Question 10

Morphology of squamous cell carcinoma

Answer 10

1. Hilar location

2. Squamous differentiation with keratin pearls

Question 11

Clinical features of squamous cell carcinoma

Answer 11

1. Metastasizes somewhat later
2. Produces paraneoplastic syndromes (especially
   hypercalcemia)

Question 12

Associations of adenocarcinoma

Answer 12

1. Commonest in females

2. Not much association with smoking

Question 13

Gross appearance of adenocarcinoma

Answer 13

1. Peripherally located (arising from alveolar septal cells or terminal bronchioles)
2. Less rapid-growing than squamous cell carcinomas
3. Scarring
4. Pleural involvement

Question 14

Histology of adenocarcinoma

Answer 14

1. Acinar
2. Papillary
3. Solid with mucin production
4. Bronchioloalveolar carcinoma

Question 15

Morphology of adenocarcinoma

Answer 15

1. Peripheral location (near pleura)

2. Glandular differentiation

Question 16

Clinical features of adenocarcinoma

Answer 16

Metastasizes readily

Question 17

Gross appearance of Bronchioloalveolar Carcinoma

Answer 17

1. Peripherally located (bronchioloalveolar regions)

2. Pneumonia-like consolidation (as multiple diffuse nodules coalesce)

Question 18

Histological appearance of bronchioalveolar carcinoma

Answer 18

1. Lepidic growth pattern
   - Growth along pre-existing structures without destruction of alveolar architecture
2. Heterogenous cellular make-up
   - Mucin-secreting bronchiolar cells
   - Clara cells (dome shaped cells with short microvilli found in bronchioles, normally secrete protective products to protect bronchiolar epithelium)
   - Type II pneumocytes

Question 19

Clinical feature of bronchioalveolar carcinoma

Answer 19

Good prognosis, well-differentiated, rare

Question 20

Histology of large cell lung carcinoma

Answer 20

1. Undifferentiated malignant epithelial tumour
2. Neoplastic cells with large nuclei, prominent nucleoli,
   abundant cytoplasm, usually well-defined cell borders
3. Lack characteristic features of squamous cell, small cell or adenocarcinomas

Question 21

Variants of large cell lung carcinoma

Answer 21

1. Giant cell carcinoma

2. Clear cell carcinoma

Question 22

Associations of small cell carcinoma

Answer 22

Strong relationship with smoking

Question 23

Gross appearance of small cell carcinoma

Answer 23

Hilar, central masses

Question 24

Histological appearance of small cell carcinoma

Answer 24

1. Small neoplastic cells (oat cells, lymphocyte-like)
2. Scant cytoplasm with ill-defined cell borders
3. Finely-granular nuclear chromatin (salt & pepper)
4. No glandular or squamous organization
5. Extensive necrosis
6. Combined small cell variant: mixed with any other non-small cell neoplastic component

Question 25

Clinical features of small cell carcinoma

Answer 25

1. Metastasizes widely
2. Most aggressive of lung tumours, virtually incurable by surgical means
3. Sensitive to chemotherapy & radiotherapy
4. Produces paraneoplastic syndromes (especially ACTH & ADH)