Textbook
1. Anatomy
2. Microbiology
3. Physiology
4. Pathology
4.1 General pathology
4.2 Central and peripheral nervous system
4.3 Cardiovascular system
4.4 Respiratory system
4.4.1 Benign tumors of the respiratory tract
4.4.2 Malignant tumors of the respiratory tract
4.4.3 Obstructive lung disease
4.4.4 COPD, chronic bronchitis, and emphysema
4.4.5 Restrictive lung disease
4.4.6 Silicosis
4.4.7 Respiratory failure and ARDS
4.4.8 Miscellaneous topics
4.4.9 Pleural effusion
4.4.10 Additional information
4.5 Hematology and oncology
4.6 Gastrointestinal pathology
4.7 Renal, endocrine and reproductive system
4.8 Musculoskeletal system
5. Pharmacology
6. Immunology
7. Biochemistry
8. Cell and molecular biology
9. Biostatistics and epidemiology
10. Genetics
11. Behavioral science
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4.4.1 Benign tumors of the respiratory tract
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4. Pathology
4.4. Respiratory system

Benign tumors of the respiratory tract

I) Vocal cord polyps, nodules and granulomas: Vocal cord polyps arise due to phonatory trauma (overuse or misuse of sound) , GERD, smoking, chemical or mechanical injury. They are typically unilateral and are seen on the membranous cord. It presents with hoarseness of voice, vocal fatigue, rough or scratchy voice and mechanical symptoms like sensation of a lump in the throat. Symptoms of vocal cord nodules and granulomas are similar to vocal cord polyps. Histology shows an increase in fibronectin and type IV collagen, decrease in hyaluronic acid, epithelial keratosis and basal membrane thickening.

Vocal cord nodules are bilateral and appear anteriorly in the vocal cords. They are caused by voice abuse like yelling, shouting etc.

Vocal cord granulomas are seen posteriorly and are associated with intubation trauma and GERD.

II) Nasal polyps: Nasal polyps are benign growths arising from the mucosa of the nasal sinuses or nasal cavity. Chronic nasal inflammation leads to the formation of nasal polyps. They are more common in individuals with allergies, asthma, low Vit D levels, cystic fibrosis, HLA-A74 and aspirin sensitivity. They present with nasal obstruction, watery rhinorrhea, postnasal drip, anosmia or hyposmia. Nasal polyps are seen as grey, single or multiple polypoid masses prolapsing into the nasal cavity, covered with pseudostratified respiratory epithelium or ciliated columnar epithelium, and composed of loose connective tissue, eosinophils, mucus secreting glands and capillaries. Increased eosinophils in nasal secretions and raised serum IL5 levels are seen. They can be diagnosed by CT scan and endoscopy.

III) Respiratory (laryngeal) papillomatosis: It is characterized by the growth of multiple, wart-like papillomas in the respiratory tract. Most common locations are the larynx and vocal cords. They are associated with HPV 6, 11, 16 and 18. An infected mother can pass HPV to their children during birth or pregnancy. Risk factors are presence of active genital warts in mother during pregnancy and childbirth, smoking, radiation exposure, oral sex and GERD.

They are benign growths, but carry high risk of mechanical obstruction of airways. They present with hoarseness of voice, raspy voice, stridor (inspiratory or biphasic), loss of voice, choking, chronic cough, dysphagia, dyspnea and failure to thrive (in children). There is a small risk of malignant transformation of a papilloma to squamous cell carcinoma. Lesions are recurrent and may recur after surgical removal.

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