Pathoma-Lung Cancer

Question 1

Lung Cancer

Answer 1

Most common cause of cancer mortality in U.S. Key risk factors are cigarette smoke, radon, and asbestsos 1. Cigarette smoke contains carcinogens, 85% of lung cancer occurs in smokers (a) Polycyclic aromatic hydrocarbons and arsenic are mutagenic (b) Cancer risk directly related to duration and amount of smoking (pack-years) 2. Radon is formed by radioactive decay of uranium in soil (a) Accumulates in closed spaces (e.g. basements) (b) Responsible for most of public exposure to ionizing radiation, 2nd most frequent cause of lung carcinoma (c) Increased risk of cancer in uranium miners

Question 2

Symptoms of Lung Cancer

Answer 2

Non-specific –> cough, weight loss, hemoptysis, post-obstructive pneumonia) Imaging often reveals a solitary nodule; biopsy necessary for diagnosis/typing of cancer 1. Benign lesions (typically younger patients) include: (a) Granuloma –> TB or fungus (Histoplasma/Blastomycosis in Midwest, Coccidioides in Southwest) (b) Bronchial hemartoma –> benign tumor composed of lung tissue and cartilage, often calcified on imaging

Question 3

Small Cell Carcinoma

Answer 3

15% of all cancers; almost exclusively in smokers, more common in men Bulky central tumor with extensive mediastinal lymph node involvement Rapid progression and early distant metastases Paraneoplastic syndromes more common, especially SIADH (hyponatremia; low sodium –> altered mental status)

Question 4

Small Cell Carcinoma Staging

Answer 4

Limited vs. Extensive Limited - disease confined to hemithorax that can be encompassed by radiation port Treat with combined chemotherapy and thoracic radiation therapy, prophylactic cranial radiation Extensive - Tumor beyond a radiation port, including malignant pleural effusion Treat with chemotherapy, radiation to bone or brain metastasis

Question 5

Non-Small Cell Carcinoma

Answer 5

Subtypes include: 1. Adenocarcinoma - most common 2. Squamous cell carcinoma - almost exclusively in smokers 3. Large cell

Question 6

Adenocarcinoma

Answer 6

Mucinous (with bronchorrhea) or non-mucinous, with lepidic (butterfly-like) features Most common tumor in non-smokers and women Peripheral tumor(s) Important to identify driver mutation for potential treatment (KRAS –> poor prognosis, EGFR –> treat with tyrosine kinase inhibitor Erlotiniv, Crizotinib, etc.) Hypertrophic Osteoarthritis (HPO) - paraneoplastic syndrome with a triad of symptoms (1) Clubbing of fingers (2) Periostitis of long bones (3) Arthritis May present with clubbing alone

Question 7

Squamous Cell Carcinoma

Answer 7

Almost exclusive to smokers, more common in males Central tumor location, generally arise in proximal airways May cause obstruction of airway with distal collapse (atalectasis) –> post-obstructive pneumonia Keratin pearls with desmosomes (intercellular bridges) May cavitate Hypercalcemia (paraneoplastic syndrome –> weakness, dehydration, altered mental status) - tumor secretes parathyroid hormone-related protein that stimulates release of calcium from bones, prevents calcium excretion

Question 8

Large Cell Carcinoma

Answer 8

10% of common carcinomas Poorly differentiated large cells –>no keratin or desmosomes, no gland or mucin production Mostly central tumor location, sometimes peripheral Poor prognosis

Question 9

Non-Small Cell Carcinoma Staging

Answer 9

TNM staging T - tumor size 1. Pleural involvement classically seen with adenocarcinoma 2. Obstruction of superior vena cava leads to distended head and neck veins with edema blue discoloration of face, arms 3. Involvement of recurrent laryngeal (hoarseness) or phrenic (diaphragmatic paralysis) nerve 4. Compression of sympathetic chain leads to Horner syndrome characterized by ptosis (drooping eyelid), miosis (pinpoint pupil), and anhidrosis (no sweating) –> usually due to apical tumor N - spread to regional lymph nodes (hilar, mediastinal) M - metastasis to other organs (liver, adrenals, bone, brain, etc.)