Module 10 Part 1 - Respiratory Tract Cytopathology Flashcards
Histology of Respiratory Tract
Squamous epithelium - non keratinising stratified
Respiratory epithelium- pseudostratified columnar
- ciliated
- mucus secreting goblet cells
- non-ciliated and cuboidal cells in smaller bronchi
- Clara cells: produce surfactant
Kulchitsky cells: are specialised neuroendocrine cells
Alveoli
- lined by two types of epithelium
- type I pneumocytes: thin walled and have a large surface area, a combination that facilitates gas exchange
- type II pneumocytes: more cuboidal and secrete surfactant
Pulmonary alveolar macrophages large phagocytic cells containing dust particles
Sputum Sample - Advantages and Disadvantages
Advantages - easily obtained - extensive area smapled - good for central tumors - accurate diagnosis - best screening test Disadvantages - difficult to obtain if not spontaneous - poor for peripheral lesions - benign tumors difficult to diagnose - less accurate for AdenoCa, metastasis and lymphomas
Criteria for Assessing Adequacy of Sputum Samples
Presence of pulmonary macrophages
Preservation or air-drying of specific samples
Fixation usually 95% ethanol or acetic acid
Bronchial Washing
Obtained using a flexible fibre-optic bronchoscope
Samples are mucoid in consistency and material is suspended in saline
Preparation from these samples require centrifugation at 1500rpm for 10 mins to sediment deposit
Indications for bronchoscopy include:
- cough, haemoptysis, bronchial obstruction, atelectasis (partial lung collapse)
Bronchial Brushing
Material is directly brushed or scraped from a lesion during a bronchoscopy
Brushing have a higher diagnostic yield for metastatic carcinoma, peripheral tumours and large necrotic cancers
Bronchiolar-Alveolar Lavage (BAL)
Performed for the assessment and monitoring of interstitial lung disease
Useful tool for obtaining material for cytology and microbiology from immunocompromised individuals with diffuse pulmonary infiltrates
Performed when saline is instilled and aspirated in serial washes through a fibre-optic bronchoscope
Fine Needle Aspirations (FNA)
Material is directly removed from a lesion using a syringe
Percutaneous (most common) and transbronchial
Skin, chest wall and pleural anaesthetized.
Under CT/US guided imaging
Slides are stained by H&E stain and examined immediately to determine specimen adequacy
Possible Complications for FNA
Pneumothorax (collapsed lung)
Haemorrhage
Air embolism
Needle track seeding
Benign Epithelium - Bronchial Epithelial Cells
Less common in sputum samples
Readily seen in post bronchoscopy samples
Shed in sheets and cohesive aggregates
Tall columnar appearance with a basophilic homogenous cytoplasm
Terminal plate may be visible on the apical surface with or without cilia
Benign Epithelium - Bronchiolar Epithelium
Lined by 2 kinds of pneumocytes, type I and type II
Type I alveolar pneumocytes are flat cells which cover > 90% of the alveolar surface
- not usually identified on cytology samples
Type II alveolar pneumocytes are columnar cells that are normally found scattered in the alveoli and secrete surfactant
- usually recognised when they become hyperplastic (reactive)
Pulmonary Macrophages
Cytoplasm finely vacuolated and usually contains phagocytosed dust particles
Oval or bean shaped, eccentric nucleus
Chromatin finely and evenly distributed, occasionally prominent nucleoli is visible
Characterised by their cytokine profile
They fight against pathogens by activating multiple immunological pathways and serve as a first line of defence
Have anti-inflammatory response to protect excessive tissue damage
Non-Cellular Elements
Curschmann Spirals
- casts of small bronchioles formed by impacted mucin, found in excess mucus production
- e.g. asthma
Ferruginous bodies
- form when iron salts precipitate into tiny rounded or fibrous inhaled dust
- the fibre is often asbestos but can be fibreglass
Alveolar proteinosis
- due to an enzymatic disorder of macrophages results in coarsely granular, PAS + debris
Corpora amylacea
- concentrically laminated calcified bodies, associated with BAC but also seen in TB
Non-Specific Reactive Changes
Reactive squamous cells Anucleate keratinized squamous cells Hyperplasia of bronchial epithelium Reactive bronchiolar cells Squamous metaplasia
Asthma
During an acute attack there is extensive loss of bronchial epithelium associated with extensive mucous and serous fluid into the bronchial lumen
Eosinophils are present in this exudate which forms mucoid plugs in the airways
Cytological findings include:
- visible mucus plugs seen in lavage fluid
- bronchial cells may appear in clusters ‘Creola bodies’
- eosinophils and Charcot Leyden Crystals
- Curschmann spirals
- inflammatory debris may contain fungal hyphae
Fungal Infections - Aspergillus
Pulmonary aspergillosis is caused by Aspergillus fumigatus and has a number of clinical syndromes, including:
- invasive pulmonary aspergillosis (IPA),
- chronic pulmonary aspergillosis (CPA)
- allergic bronchopulmonary aspergillosis (ABPA)
- Aspergilloma
