This document summarizes different types of lung cancers and respiratory diseases. It describes the four main types of lung cancer - adenocarcinoma, squamous cell carcinoma, small cell carcinoma, and large cell carcinoma - and discusses their characteristics, causes, and treatments. It also outlines other respiratory conditions like laryngeal cancer, pleural diseases, and metastatic lung tumors. Various respiratory medications are explained, including inhaled bronchodilators, corticosteroids, leukotriene inhibitors, and expectorants.

1. Respiratory Pathology
Dr. Okon MRCS

2. Lung Cancer Types
 Adenocarcinoma
 More commonly seen in women and nonsmokers.
 Causes a peripheral gray-white mass, and the tumor may develop in
areas of parenchymal scarring (scar carcinoma). Microscopically,
 Aciinar, papillary, mucinous, and solid.
 Atypical adenomatous hyperplasia—progresses to adenocarcinoma in
situ (noninvasive well-differentiated tumor <3 cm) and to minimally
invasive tumor before progressing to invasive adenocarcinoma.
 Squamous cell carcinoma (SCC)
 strongly related to smoking and affects males more than females.
 Squamous cell carcinoma arises from bronchial epithelium
 metaplasia → dysplasia → carcinoma in situ → invasive carcinoma
 Usually centrally located.
 Microscopically, nests of squamous cells with intercellular bridges
(desmosomes) and keratin production (“squamous pearls”).

3. Lung Cancer Types
 Small cell carcinoma
 Strong association with smoking, and affects males more
than females.
 Very aggressive, with rapid growth and early dissemination.
 Associated with paraneoplastic syndromes.
 Gross examination demonstrates central, gray-white
masses.
 Microscopic examination shows small round or polygonal
cells in clusters
 Electron microscopy shows cytoplasmic dense-core
neurosecretory granules.
 Treatment - chemotherapy and radiation.
 Prognosis is poor

4.  Large cell carcinoma
 Large anaplastic cells without evidence of differentiation
 Intrathoracic spread of lung cancer
 Lymph nodes - hilar, bronchial, tracheal, and mediastinal;
 Pleura (adenocarcinoma)
 Lung apex causing Horner syndrome (Pancoast tumor).
 Horner Syndrome causes ipsilateral: Ptosis, Miosis, Anhidrosis,
Enophthalmos
 Obstruction of the superior vena cava - superior vena cava
syndrome, characterized by distended head and neck veins, plethora,
and facial and upper arm edema.
 Esophageal obstruction - dysphagia.
 Nerve Impingement – Recurrent laryngeal nerve involvement -
hoarseness, while phrenic nerve damage causes diaphragmatic
paralysis.
 Extrathoracic sites of metastasis include adrenal (>50%), liver, brain,
and bone.

5. Bronchial carcinoids
 Bronchial carcinoids
 Younger age group (mean age 40 years)
 A polypoid intrabronchial mass or plaque
 Characterized on light microscopy by small,
round, uniform cells growing in nests (organoid
pattern).
 Electron microscopy by cytoplasmic dense-core
neurosecretory granules.
 Atypical carcinoid is more aggressive than
typical carcinoid.

6.  Metastatic carcinoma
 Most common malignant neoplasm in the lung.
 Multiple, bilateral, scattered nodules
 Common primary sites include breast, stomach, pancreas,
and colon.
 Hamartomas are benign tumors;
 Occur more commonly in middle-aged adults but also
occur in children.
 Appear as coin lesions on chest x-ray.
 Microscopically, they are comprised of nonencapsulated
fibromyxoid tissue.
 Carney triad is the finding of a hamartoma with a
predominantly cartilaginous component (pulmonary
chondroma), an extra-adrenal paraganglioma and a

7. Paraneoplastic syndromes
 Endocrine/metabolic syndromes
 Cushing syndrome secondary to ACTH production
 SIADH secondary to ADH production
 Hypercalcemia secondary to PTH production
(squamous cell carcinoma).
 Eaton-Lambert syndrome
 Acanthosis nigricans
 Hypertrophic pulmonary osteoarthropathy is
characterized by periosteal new bone formation
with clubbing and arthritis.

8. LARYNGEAL CANCER
 Laryngeal squamous cell carcinoma causes
hoarseness, difficulty swallowing,
 pain, hemoptysis, and eventual respiratory
compromise. Risk factors include
 smoking, alcohol, and frequent cord irritation
(professional singing or lecturing).
 Complications include direct extension,
metastases, and infection.

9. DISEASES OF THE PLEURAL
CAVITY
 Pleural effusion - accumulation of fluid in the pleural cavity.
 Empyema refers to pus in pleural space.
 Chylothorax refers to chylous fluid in the pleural space
 Pneumothorax- air in the pleural cavity.
 Due to traumatic penetrating chest wall injuries or
spontaneous rupture of apical blebs in typically tall young
adults (spontaneous pneumothorax).
 Tension pneumothorax - life-threatening shift of thoracic
organs across midline occurs.
 Hemothorax is the presence of blood in the pleural cavity.
 Trauma
 Hypotension and shift of the trachea to the unaffected side.
 Chylothorax is lymphatic fluid in the pleural cavity.
Malignancy is a common cause.

10. Respiratory Pharmacology
 Inhaled β2-Adrenergic Selective Agonists
 Short acting, such as albuterol or levalbuterol, or long acting, such as
salmeterol or formoterol.
 Act on β2 receptors of intracellular adenyl cyclase, the enzyme that
catalyzes the conversion of adenosine triphosphate (ATP) to cyclic
adenosine monophosphate (AMP).Results in increased cyclic AMP levels in
bronchial smooth muscle, causing bronchial smooth muscle relaxation.
 Also thought to inhibit mast cell release of immediate hypersensitivity
mediators.
 Clinical Uses: Alleviate acute bronchospasm in acute asthma exacerbations
(most common); as prophylaxis against exercise-induced asthma; to
alleviate bronchospasm in COPD;
 during general anesthesia; in NRDS or RSV infection; and as rapid treatment
of critical hyperkalemia (drive K+ into cells).
 Side Effects: tachycardia and palpitations (caused by some β1 effects,
although
 levalbuterol is more β2 selective than albuterol and causes less tachycardia),
tremors, anxiety, and hypokalemia

11. Muscarinic Antagonists
 Muscarinic Antagonists
 Ipratropium (short acting) and tiotropium (long
acting).
 Antagonize acetylcholine at muscarinic receptors,
prevent bronchoconstriction by preventing increase
in cyclic guanosine monophosphate (cGMP)
 Reduce secretions from mucous glands.
 Clinical Uses: COPD maintenance therapy,
asthma exacerbations.
 Side Effects: Nasal mucosa dryness,
xerostomia, bronchitis, and sinusitis.

12. Phosphodiesterase-4 Inhibitors
 Phosphodiesterase-4 Inhibitors
 Roflumilast.
 Selectively inhibit PDE4 leading to
accumulation of cyclic AMP (cAMP) within
inflammatory and structural cells.
 Clinical Uses: They are used in the treatment
of COPD.
 Side Effects: Headache, diarrhea, and weight
loss.

13.  Methylxanthines - theophylline.
 Cause bronchodilation through inhibition of phosphodiesterase, the enzyme that
breaks down cyclic AMP, thus increasing cyclic AMP levels, Also thought to increase
contraction force of diaphragm by increasing Ca2+ uptake into the muscle.
 Clinical Uses: Asthma controller medication and treatment for COPD.
 Side Effects: Tremor, irritability, nausea, vomiting, and tachyarrhythmia.
 Have a narrow therapeutic index
 Cromolyn
 Mast cell stabilizer (blocks histamine release) and antiinflammatory agent.
 Prevents bronchoconstriction in response to inhaled antigens.
 Clinical Uses: Asthma controller medication and to treat allergic rhinitis.
 Side Effects: Cromolyn has minimal toxicity.
 Omalizumab
 Anti-IgE monoclonal antibody.
 Clinical Uses: Uses include treatment of asthma that is poorly controlled with
steroids or beta agonists.
 Side Effects: Omalizumab has minimal toxicity.

14. Leukotriene Inhibitors
 Leukotrienes - mediators synthesized by leukocytes that promote
bronchoconstriction and neutrophil chemotaxis.
 Inhibition - an important target for asthma therapy.
 Montelukast, Zafirlukast
 Selectively antagonize leukotriene receptors.
 Clinical Uses: Asthma controller medication and are especially useful in
triad asthma (asthma induced by aspirin, NSAID use).
 Acute prevention of exercise-induced bronchoconstriction and for allergic
rhinitis.
 Side Effects: Leukotriene inhibitors have minimal toxicity. Headache can be
a side effect.
 Zileuton
 Selectively inhibits 5-lipoxygenase, the enzyme that catalyzes the
formation of leukotrienes from arachidonic acid.
 Used as an asthma controller medication.
 Side Effects: This agent has minimal toxicity.

15.  Corticosteroids
 Inhaled: Beclomethasone, budesonide, fluticasone, mometasone
 Oral: Prednisone and dexamethasone
 Corticosteroids exert antiinflammatory effects by inhibiting
inflammatory cells and production of inflammatory mediators.
 Clinical Uses: Inhaled corticosteroids are first-line asthma controller
medications; oral corticosteroids are used to treat asthma
exacerbations unresponsive to other measures, as well as other
inflammatory conditions.
 Side Effects
 Inhaled: Minimal systemic absorption and therefore minimal toxicity.
 Oral: Osteoporosis, immunosuppression, hypertension, Cushing
syndrome, hyperglycemia, cataracts, glaucoma, fluid retention,
avascular necrosis of femoral head, depression, mania, adrenal
insufficiency (on cessation).


16.  Expectorants
 Guaifenesin
 Reduces the viscosity of tracheal and bronchial secretions.
 Clinical Uses: It is used as an expectorant in over-the-counter
medications (e.g., Robitussin Mucinex) and in intensive care
units to help patients on mechanical ventilation clear secretions.
 Side Effects: Guaifenesin has minimal toxicity.
 N-Acetylcysteine
 cleaves disulfide bonds in mucous glycoproteins, thus
loosening thick sputum. It functions as a glutathione donor in
acetaminophen overdose.
 Clinical Uses: It is a mucolytic used for cystic fibrosis,
tracheostomy care, or any respiratory condition with abnormal
or inspissated mucous secretions and in acetaminophen
overdose.
 Side Effects: N-Acetylcysteine has minimal toxicity.