Respiratory system Flashcards
Sarcoidosis
- Seen in females»_space; males
- Type IV hypersensitivity, so CD4 TH1 cells can be seen ➡️ granuloma
- Immunologically mediated, associated with HLA-A1, HLA-B8
Presenting complaints of sarcoidosis
- Eye: uveitis
- Salivary gland’s: Sicca syndrome/ Sjögren’s syndrome
- Lung is most commonly affected
- Hillary lymph node enlargement
- Skin, genitals and bone marrow can be affected
Sarcoidosis, on histological examination
1. Non caseating/ naked granuloma: Lymphocytes collar absent 2. Asteroid bodies: Star shaped inclusions in giant cells 3. Schaumann bodies: Basophilic Ca+2 concretions
Investigation findings of sarcoidosis
- Increased ACE levels
- Increased Ca+2 ➡️ metastatic calcification
- Increased CD4:CD8 ratio (normal is 2:1)
- Kveim’s test positive
Hypersensitivity pneumonitis
It is an example of (both type III and) Type IV hypersensitivity
Honey combing and fibrosis of lung is seen
Histoplasmosis
Caused by Histoplasma capsulatum
Seen in pigeon/ bird breeders (because fungus lives in bird droppings)
Grossly:
Tree bark appearance (like syphillitic aneurysm)
H&E:
caseating granuloma (like TB)
Acid fast bacteria
Mycolic acid
My. Mycobacterium tuberculosis Nose. Novartis Is. Isospora Cold. Cryptosporidium and Hot. Hooklets of hydatid cyst
Virulence factor of Mycobacterium tuberculosis
Cord factor
This bacteria can be seen in necrotic area
Primary tuberculosis
Occurs on 1st exposure
Lesion in lower part of upper lobe and upper post of lower lobe subpleurally: Ghon’s focus
Ghon’s focus + lymph node involvement ➡️ Ghon’s complex
If calcified, Ranke complex
Secondary or activation tuberculosis
Affects apex
Supraclavicular region of lung- Puhl’s focus
Infraclavicular region - Assmann’s focus
Disseminated/ military tuberculosis
1-2 mm disseminated lesions all over
Most common cause of community acquired pneumonia
Streptococcus pneumonia
Pathological classification of pneumonia
- Lobar pneumonia
2. Lobular (bronchial) pneumonia
4 stages of lobar pneumonia
1. Congestion : 1-2 days Full of RBC and exudate fluid 2. Red hepatisation: 2-4 days Fibrin and RBC 3. Grey hepatisation: 4-8 days RBC disintegration 4. Resolution: 9-10 days Most common outcome
Etiological classification of pneumonia
1. Typical: bacterial Lots of exudate Purulent cough 2. Atypical: Vital, mycoplasma, respiratory syncytial virus, chlamydia pneumonia Less exudate Non purulent cough
TB infects
Type of cells which are increased after TB infection
Macrophages
Lymphocytes
Features of viral pneumonia
- Presence of interstitial inflammation
- Bronchiolitis
- Deficiency of alveolar exudate
- Multinucleate giant cells in bronchial wall
Most common malignancy of lung
Metastasis
Most common is from breast carcinoma
Most common benign lung tumour
Pulmonary hamartoma
Abnormal proliferation of cells
X-rays: coin shaped lesions
Classification of lung tumours
- Small cell lung cancer
- Non-small cell cancer:
a) adenocarcinoma
Precursor lesson:
• atypical adenomatous hyperplasia
• bronchoalveolar carcinoma (BAC/ adenocarcinoma in situ)
b) squamous cell carcinoma
Precursor lesion: squamous cell carcinoma in situ
Squamous cell carcinoma of lung
Centrally located Cavitary lesions formed Smoking associated Males > females Paraneoplastic syndrome: hypercalcemia due to PTHrp (related peptide) Pathogenesis: p53 gene mutations
Microscopy and immunohistochemistry of squamous cell carcinoma
Microscopy: 1. Keratin pearls 2. Desmosomes (adhere 2 squamous cells) Immunohistochemical markers: 1. CK+ (cytokeratin) 2. p63 3. p40
Adenocarcinoma of lung
M/C lung cancer in women and in non smokers
Peripherally lesions
Paraneoplastic syndrome: migratory thrombophlebitis
H&E: glands lined by malignant cells
IHC markers: TTF-1, NAPSIN-A
Bronchoalveolar carcinoma
Adenocarcinoma in situ
• Good prognosis
• Tumour cells grow along the bronchoalveolar lining
• Butterflies in a fence/ lepidic/ filigree pattern
Small cell carcinoma of lung
Strongest association with smoking Males> females Paraneoplastic syndrome: Cushing syndrome, SIADH (M/C PNS) Produces maximum PNS Starts centrally ➡️ peripheral, worst prognosis Metastasises to brain Chemosensitive Pathogenesis: L-MYC mutation
Microscopy of small cell carcinoma of lung
- Small cells
- Nuclear moulding
- Azzopardi effect:
Tumour cells (fragile) break ➡️ release nuclear chromatin ➡️ deposited in blood vessel wall ➡️ basophilic blood vessel walls - Salt and pepper chromatin
On electron microscopy: dense core neurosecretory granules
IHC markers for small cell carcinoma of lung
- NSE: neuron specific enolase
- Chromogranin
- Synaptophysin
The H&E , IHC and electron microscopy findings are same for neuroendocrine tumours like
- Pheochromocytoma
- Carcinoid tumour
- Paraganglioma
- Carotid body tumours
- Small cell carcinoma of lung
Large cell carcinoma of lung
Large pleomorphic cells Aggressive tumour PNS: gynaecomastia Clinically: Cough, haemoptysis Weight loss Dyspnoea
Pancoast tumour
Lung cancer at the apex Compresses cervical sympathetic chain ➡️ Horner’s syndrome Punjabi. Ptosis M. Miosis E. Enophthalmos A. Anhidrosis L. Loss of ciliospinal reflex
Spread of lung carcinomas
- Directly: to recurrent laryngeal nerve ➡️ hoarseness
- Metastasis to brain (adrenals)
- To lymph nodes (hilar)
Carcinoid tumour
Arises from Kulchitsky cells of lungs Clinical presentation: 1. Flushing 2. Sweating 3. Diarrhoea Microscopy, electron microscopy and IHC are same as all neuroendocrine tumours like small cell carcinoma
Classification of carcinoid tumour
1. Typical: <2 mitosis/10 HPF No necrosis 2. Atypical: 2-10 mitosis/10 HPF Necrosis present
Most common cause of pleural malignancy
Metastasis
Commonly from lung
Malignant mesothelioma
Most specific lung carcinoma associated with asbestos exposure
• duration of exposure:>25 years (otherwise lung adenocarcinoma)
IHC markers:
1. Calretinin (best marker)
2. CK 5/6
3. WT-1
Microscopy of malignant mesothelioma
Three types of cells: 1. Spindle cells 2. Epitheloid cells 3. Sarcomatoid cells Electron microscopy: Long slender microvilli/ tonofilaments (Opp of lung adenocarcinoma where short plump microvilli are seen)
Acinus
Combination of respiratory bronchiole, alveolar duct and alveolar sac
Type 2 pneumocytes
5% of cells
Involved in repair and produce surfactant
Part of respiratory tract not lined by pseudostratified ciliated columnar epithelium
Vocal cords is lined by stratified squamous epithelium
Adult respiratory distress syndrome is also called as
Its properties
- Acute lung injury- ALI
- Diffuse alveolar damage- DAD
- Hyaline membrane disease
Microscopy:
Hyaline production and deposition in sacs
X-ray:
B/L diffuse infiltrate ➡️ white-out appearance
Pathogenesis of adult respiratory distress syndrome/ALI/DAD
- Toxin in alveoli
- Macrophage activation
- IL-1, IL-6 and TNF-α secretion
- Neutrophil recruitment in capillaries
- Protease secretion:
• endothelial damage
• procoagulase activation ➡️ - Production of fibrin
- Fibrin leaks out of capillaries
- Hyaline membrane
Macrophage activation also causes TGF-β secretion
Obstructive lung diseases
1. COPD: • Chronic bronchitis • Emphysema 2. Bronchiectasis 3. Bronchial asthma
Emphysema
Irreversible dilation and destruction of air spaces distal to the terminal bronchioles Involves: 1. Respiratory bronchioles 2. Alveolar ducts 3. Alveolar sac Gross: bullae due to destruction of walls C/F: Pursed lip breathing Pink puffers
Pathogenesis of emphysema
- Smoking
- α-1 Antitrypsin deficiency, which is an anti-elastase/anti-protease
• Both increases elastase ➡️ tissue damage
Types of emphysema
1. Centriacinar: Central acinar affected 2. Panacinar: Entire acinus affected 3. Distal acinar/ paraseptal : Alveolar sacs/ducts affected 4. Irregular: M/C histologically
Differences between centriacinar and panacinar emphysema
1. Centriacinar: • M/C clinically • Smoking associated • Upper lobes affected 2. Panacinar: • α-1 Antitrypsin deficiency associated • Lower lobes affected
Type of emphysema associated with spontaneous pneumothorax
Distal acinar/ paraseptal emphysema where alveolar sacs/ ducts are affected
Rupture in alveolar sacs leads to spontaneous pneumothorax
Definition of chronic bronchitis
Persistent productive cough for at least 3 months, in at least 2 consecutive years in absence of any other identifiable cause
Reid’s index
Ratio of thickness of mucus glands layer to thickness of basement membrane between epithelium and cartilage =bc/ad
Normal: 0.4
Increased in chronic bronchitis
Chronic bronchitis pathogenesis
- Smoking (in 90%)
- Epithelial irritation
- Increased mucous production:
• Increased Reid’s index
• increased risk of 2° infections
• goblet cell hyperplasia
Chronic bronchitis is a pre malignant condition
It is not associated with amyloidosis unlike other chronic inflammations
Bronchial asthma
Reversible bronchoconstriction and inflammation of airways
Type I hypersensitivity reaction
Airway remodelling occurs
Bronchial asthma types
1. Allergic/ Atopic/ Extrinsic: • Type I hypersensitivity • increased IgE • in children usually • family history maybe present 2. Intrinsic/ Non-atopic: • IgE not raised • in adults usually • no family history
Bronchial asthma genetics
- IL-13 gene polymorphism
- ADAM 33 polymorphism
- Gene for atopy ➡️ chromosome 5q
- Increased YKL 40 leads to increased severity
Bronchial asthma sputum microscopy
1. Curschmann’s spirals: Whorled mucus plugs 2. Charcot Leyden crystals: Eosinophilic membrane protein Galectin 10 3. Creola bodies: Slighted mucus epithelium
Airway remodelling
- Increased fibrosis
- Increased vascularity
- Increased smooth muscles
Bronchiectasis
Abnormal permanent dilation of bronchi and bronchioles
HRCT is taken for diagnosis
Complications:
1. Empyema
2. Lung abscess
3. Amyloidosis
Probe reaches almost upto pleura (rather than stopping 1-4 cm before)
Causes of bronchiectasis
- Kartagener’s syndrome
- Cystic fibrosis
- Obstruction
- Infection
The last 3 affects the lower lobes
Kartagener’s syndrome/ Immotile cilia syndrome/ 1° ciliary dyskinesia
Mutation in dynein arm of cilia Triad: 1. Sinusitis 2. Situs inversus 3. Bronchiectasis Infertility
Restrictive lung disorders
1. Fibrosing lung disorders: • Usual interstitial pneumonia • Non-specific interstitial pneumonia • Cryptogenic organising pneumonia 2. Pneumoconiosis / occupational lung disease: • Coal worker’s pneumoconiosis • Caplan syndrome • Silicosis • Asbestosis
Factors for development of pneumoconiosis
- Size of particles: <5 microns are dangerous
- Solubility of particles: inversely
- Duration of exposure
- Synergistic factors like smoking
Coal worker’s pneumoconiosis
Usually affects upper lobes Three types: 1. Asymptomatic anthracosis 2. Simple coal worker’s pneumoconiosis: • coal macules and nodules 3. Complicated coal worker’s pneumoconiosis: • progressive massive fibrosis
Caplan syndrome
Coal worker’s pneumoconiosis + rheumatoid arthritis
Grinder’s disease/ Silicosis/ Miner’s disease
- M/C occupational lung disease in the world
- M/C particle causing silicosis is quartz
- increased risk of TB and cancer
- X-ray: egg cell calcifications of lymph nodes
- produces nodular fibrosis of lung