Chapter 10 Answers to self-check questions

10.1 What is the function of the upper and lower respiratory tract?

The upper respiratory tract is involved in the transportation of air to the lungs. During this passage, air is warmed and humidified and particulate matter is removed. The upper respiratory tract also acts as the first line of defence against microorganisms. The main role of the lower respiratory tract is gaseous exchange.

 

10.2 What do you understand by the term ‘respiratory epithelium’?

Respiratory epithelium is the type of epithelium found in the respiratory tract. It is a pseudostratifi ed epithelium as although all cells are in contact with the basement membrane, the arrangement of nuclei at diff erent levels, gives the impression of multilayering or stratifi cation. Its function is to warm and moisten the air and protect the airways against pathogens and dust particles. It consists of three main cell types: ciliated columnar cells, mucus secreting goblet cells, and basal cells. The majority of the cells are ciliated columnar cells, which move the mucus secreted by the goblet cells towards the pharynx. Basal cells are small cube shaped cells, which are the precursor cells of columnar and goblet cells.

 

10.3 List some of the advantages and disadvantages of different sampling methods in respiratory cytology.

	Advantages	Disadvantages
Sputum	Non-invasive technique, easily reproduced. Useful in patients who are too ill to tolerate other sampling procedures.	Cells suffer degenerative changes. Lower sensitivity than bronchial brushing and FNA. Widespread use of bronchoscopy has contributed to its demise.
Bronchial washings	Allows sampling of the areas that cannot be visualized by bronchoscope.	Cells can undergo degenerative changes if processing is delayed.
Bronchial brushings	Allows direct sampling of areas that can be seen at bronchoscopy and also lesions which cannot be visualized. Material can be collected for ancillary techniques such as immunocytochemistry. Suitable specimen type for on-site assessment of adequacy by biomedical scientists.	No major disadvantages; may cause mild bleeding.
Transbrochial fine needle aspiration	Allows sampling of lesions that lie beneath the epithelium. Allows sampling of mediastinal lymph nodes. Material can be collected for ancillary techniques such as immunocytochemistry. Allows for assessment of on-site adequacy by biomedical scientists.	Technically more difficult than bronchial brushings, but well tolerated by the patients.
Transthoracic fine needle aspirations	Allows sampling areas that cannot be sampled by other means. Material can be collected for ancillary techniques such as immunocytochemistry. Allows for assessment of on-site adequacy by biomedical scientists. Allows sampling of peripheral lesions.	Can occasionally cause pneumothorax.
Bronchoalveolar lavage	Useful in diagnosis of opportunistic infections in immunocompromised patients and investigation of interstitial lung disease.
Biopsy imprints	Allows for assessment of on-site adequacy by biomedical scientists.

 

 

10.4 Why is the recognition of hyperplastic bronchial epithelium important?

Hyperplastic bronchial epithelium is a common cause of false positive diagnosis in respiratory cytology as their nuclei may enlarge, and even form clusters resembling clumps of adenocarcinoma. These clusters may be diffi cult to examine but their nuclei should retain a normal chromatin pattern and fi nding cilia is a clue to their benign nature.

 

10.5 What could be the possible explanation for the drop in lung cancer death rates in men, whilst the rate in women is increasing?

One possible explanation could be the diff erence in smoking habits between males and females. The impact of smoking takes decades to show its eff ect. When the harmful eff ects of smoking became known, larger numbers of male smokers, who had been smoking for longer, gave up smoking than women. An estimate by the Scottish Executive Health Department predicts that death rates in women will continue to rise slightly between 2010 and 2014.

 

10.6 What are the symptoms of lung cancer?

Symptoms of lung cancer are varied. Symptoms due to the effects of the primary tumour include: shortness of breath, cough, haemoptysis, chest pain, excessive fatigue, and severe weight loss. Symptoms due to metastatic spread of tumour include jaundice, fractures, or neurological symptoms.

 

10.7 Why is staging of lung cancer important?

Staging is important when deciding on treatment, as lung cancer therapies are geared towards a specifi c stage. Staging is also important when deciding the prognosis of a given patient.

 

10.8 Why is it important to correctly distinguish a bronchial carcinoid from a small cell anaplastic carcinoma?

Although both small cell anaplastic carcinoma and bronchial carcinoids arise from cells of the diff use neuroendocrine system, they behave very diff erently. Small cell anaplastic carcinoma is a fastgrowing aggressive tumour that cannot generally be cured and has a very poor prognosis. Treatment for small cell anaplastic carcinoma is typically by chemotherapy and radiotherapy. Typical bronchial carcinoid, on the other hand, is a slow-growing tumour that can be surgically cured. Five-year survival for typical carcinoid is over 90% compared to small cell carcinoma that has five-year survival rates of between 1 to 38% depending on the stage of the tumour at diagnosis. It is prudent to biopsy suspected carcinoids at bronchoscopy.