L8 - Respiratory Cytology Flashcards
Cytology
- The study and identification of disease by light microscopy examination of celluar material
- Used as a diagnostic tool as well as a screening test
- The main role of diagnostic cytology in pathology is the identification of malignant or premalignant cells by recognising changes in cell morpholgy
Types of samples
- Exfoliative
- Fine needle aspiration
- Abrasive
Histology of respiratory tract
Respiratory epithelium: pseudostratified columnar
- Ciliated
- Muscus secreting goblet cells
- Basal or reserve cells
- Non ciliated and cuboidal cells in samller bronchi
- Clara cells: produce surfactant (specialised cells that line the bronchioles)
- Kulchitsky cells: are specialised neuroendocrine cells
- Alveoli
- Macrophages
Alveoli
- gas exchanging structure of the lungs
Lined by two types of epitelium:
- Type 1 pneumocytes: thin walled and have a large surface area, a combination that facilitates gas exchange
- Type 2 pneumocytes: are more cuboidal and secrete surfactant
Pulmonary macrophages
large phagocytic cells containing dust particles
Sputum samples
- traditional specimen
- early morning deep cough
- if a specimen cannot be produced spontaneously, representative samples may be obtained during physiotherapy or through nebulizer induced deep cough
Advantages of sputum samples
- Easily obtained
- Extensive area sampled
- Good for central tumours
- accurate diagnosis
- best screening test
Disadvantages of sputum samples
- difficult to obtain if not spontaneous
- cannot localise lesion
- poor for peripheral lesions
- benign tumours difficult to diagnose
- less accurate for adeno carcinoma, metastasis and lymphomas
Bronchial washings
- obtained useing a flexible fibre-optic bronchoscope
- samples are mucoid in consistency and material is suspended in saline
- preparation from these samples requires centrifugation at 1500rpm for 10 min to sediment deposit
- indications for bronchoscopy indclude cough, haemoptysis, bronchial obstruction, and partial lung collapse
Bronchial brushings
- material is directly brushed or scraped from a lesion during a bronchoscopy
- brushings have a higher diagnostic yield for metastatic carcinoma, peripheral tumours and large necrotic cancers
- usually clinical suspicion of infection warranting special staining procedures (e.g. methanamine silver for fungi)
- overall sensitivity of bronchial brushing is 70%
Bronchiolar-alveolar lavage (BAL)
- performed for the assessment and monitoring of interstitial lung disease
- a useful tool for obtaining material for cytology and microbiology from immunocompromised individuals
- performed when saline is instilled and aspirated in serial washes through a fibre-optic
Fine needle aspiration (FNA)
- material is directly removed through aspiration of a subcutaneous lesion using a syringe
- percutaneous (most common) and transbronchial
- skin, chest wall and pleural anaesthetised
- under CT/US guided imaging
- slides are stained (ROSE - rapid onsite evaluation) by H&E stain and examined immediately to determine specimen adequacy
Possible complications for FNA
- pneumothorax
- haemorrage
- air embolism
- needle track seeding
Epithelial cells in sputum and respiratory samples
- non keratinised stratified squamous epithelial cells
Respiratory bronchial epithelial cells:
- ciliated columnar cells
- columnar cells in sheets and groups
- goblet cells
- multinucleated bronchial cells
Bronchial epithelium 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
Bronchial epithelium cells - pneumocytes
- type 1 alveolar pneumocytes are flat cells which cover 90% of the alveolar surface
- these are not usually identified on cytology samples
- type 2 alveolar pneumocytes are columnar cells that are normally found scattered in the alveoli and secrete surfactant
- usually recognised when they become hyperplastic
Cells of non-epithelial origin
- alveolar macrophages
- pulmonary macrophages
- lymphocytes
- eosinophils
Cells of non-epithelial origin: Alveolar macrophages
- bone marrow derived histocytes found free in the alveolar space
- hallmark of a satisfactory sputum sample
- similar to histocytes
- vary in size; often have round to oval or bean shaped nucleui, may be mononucleated, bi-nucleated or multi-nucleated
- multinucleated macrophages are often found in granulomatous disease such as sarcoid and TB but are not specific for granulomas
- are characteristically phagocytic, carbon. haemosiderin and lipid
Non - celluar elements
Curshmann spirals
Ferruginous bodies
Alveolar proteinosis
Corpora amylacea
Curshmann spirals
casts of small bronchioles fromed 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 it can be fibre glass
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 sqaumous cells
- anucleated keratinised sqaumous cells
- hyperplasia of bronchial epithelium
- sqaumous 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
