Additional information

Solitary Pulmonary Nodule Characters

• Common radiological finding
• Well-circumscribed, round lesion, <3 cm diameter, surrounded by aerated lung
• Benign nodules are more common and are seen in infectious granulomas like tuberculosis, coccidioidomycosis, histoplasmosis; hamartomas, sarcoidosis
• Malignant nodules seen in adenocarcinoma, SCC, carcinoid tumors, lymphomas
• Current or past history of smoking, age>65 years, history of cancer, high risk findings on imaging, are associated with higher risk of malignancy
• High risk findings on imaging are spiculated lesions, ground glass, asymmetric or eccentric calcification, subsolid lesions, lesions located in an upper lobe and doubling time of either <1 month or more than 1 year; size>10 mm
• Low risk findings on imaging are nodules with smooth borders; diffuse, central, concentric or popcorn pattern of calcification; doubling time of 1 month to 1 year; size<5mm
• Always obtain past lung imagings for comparison

Evaluation of solitary pulmonary nodule

Non-small cell lung cancer or NSCLC: It includes squamous cell carcinoma, large cell carcinoma, adenocarcinoma of the lung and less common forms such as pleomorphic carcinoma, carcinoid tumors and unclassified types that are not small-cell cancers in the lung.

Risk factors for NSCLC

• Current or past history of cigarette, pipe or cigar smoking. Risk is higher if total duration in years of smoking is more
• Exposure to secondhand smoke
• Exposure to asbestos, arsenic, chromium, nickel, beryllium, soot, tar
• Radiation exposure from radiotherapy, radon, imaging tests like CT scans, nuclear emissions
• City dwellers, industrial areas, air pollution
• Beta carotene supplementation in heavy smokers
• HIV, immunodeficiencies
• Family history
• Old scars e.g. from tuberculosis, surgery, infections, injuries

Paraneoplastic syndromes seen in lung cancer

Small cell or oat cell carcinoma

• SIADH:Hypo-osmolar hyponatremia, high urine osmolality
• ANP or atrial natriuretic peptide causing hyponatremia
• Ectopic Cushing’s Syndrome: Hypercortisolism due to ectopic ACTH or CRH secretion; hyperglycemia, hypokalemia
• Anti-Hu syndrome: Presence of anti-Hu or type 1 anti-neuronal nuclear antibodies or ANNA1; encephalomyelitis, cerebellar degeneration, sensory neuropathy, GIT paresis, opsoclonus-myoclonus syndrome
• Lambert-Eaton syndrome: Caused by antibodies to presynaptic voltage gated calcium channels leading to decreased release of ACh; proximal muscle weakness, decreased tendon reflexes, autonomic instability
• Polymyositis, dermatomyositis
• Sign of Leser-Trelat: Sudden appearance of multiple seborrhoeic keratoses
• Retinopathy
• Acromegaly due to ectopic GHRH secretion

Squamous cell carcinoma

• Hypercalcemia: secretion of PTHrP* by tumor cells; poor prognosis; treat by cancer therapy, normal saline, bisphosphonates, loop diuretics, calcitonin
• Polymyositis, dermatomyositis
• Hypertrophic pulmonary osteoarthropathy: Periostitis, abnormal proliferation of cutaneous and osseous tissues of the extremities; clubbing, arthritis.

* PTHrP uses the same receptor as PTH. However, PTHrP does not stimulate 1-hydroxylase activity or increase Vit D levels. PTHrP causes hypercalcemia by increasing osteolysis and decreasing calcium excretion by the kidney.

Morphological types of emphysema

• Centriacinar: Destruction of central portions of the acini and respiratory bronchioles. Associated with cigarette smoking; most prominent in upper lobes
• Panacinar: Destruction of entire alveolar unit distal to the terminal bronchiole; seen in AAT deficiency; most prominent in lower lobes
• Distal acinar or paraseptal: Involvement of distal alveoli, pleura and interlobular septa; seen more commonly in males and smokers; more prominent in upper and middle lung zones; associated with subpleural bullae and spontaneous pneumothorax

Extrinsic asthma (allergic asthma)

• More common in children and young adults
• Occurs as an allergic response to dust, pollen, animal dander, fungal spores, food, drugs, etc.
• Typically disappears by adulthood
• Associated with eczema, allergic rhinitis
• High allergen specific IgE, eosinophilia present but not always prominent

Intrinsic asthma (non-allergic asthma)

• Often first presents in adulthood
• Absence of allergies and atopy
• Triggers are cold exposure, emotional stress, exercise, infections, associated with Staphylococcal superantigens
• Associated with nasal polyps, aspirin sensitivity and sinusitis
• IgE normal, eosinophilia more prominent

FEV1/FVC ratio: the percentage of the FVC expired in one second. Spirometry is diagnostic for COPD when the post bronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio is less than 0.7. An FEV1/FVC ratio<50% is seen in severe cases of COPD.

Spirometry findings in obstructive and restrictive lung diseases.

Obstructive lung disease

• Decreased FEV1
• Decreased FEV1/FVC ratio <0.7 or <70%
• FVC normal or decreased
• Decreased FEF 25-75
• MVV low
• Residual volume increased
• TLC increased
• FRC increased

Restrictive lung disease

• Decreased or normal FEV1
• FEV1/FVC ratio >= 0.7 or >= 70%
• FVC decreased
• Decreased FEF 25-75
• MVV normal, decreased in neuromuscular weakness
• Residual volume decreased
• TLC decreased
• FRC decreased

FEV1: forced expiratory volume in one second; total volume of air a patient is able to exhale in the first second during maximal effort

FVC: forced vital capacity; total volume of air a patient is able to exhale for the total duration of the test during maximal effort

FEF 25–75%: forced expiratory flow over the middle one-half of the FVC; the average flow from the point at which 25% of the FVC has been exhaled to the point at which 75% of the FVC has been exhaled. A decreased FEF25-75 reflects the collapse of the small airways and is a sensitive indicator of early airway obstruction.

MVV is maximum voluntary ventilation, also called MBC or maximal breathing capacity.

If the patient has an obstructive defect, the physician should determine if it is reversible based on the increase in FEV1 or FVC after bronchodilator treatment (i.e., increase of more than 12% in patients five to 18 years of age, or more than 12% and more than 200 mL in adults. Obstructive defects in persons with asthma are usually fully reversible, whereas defects in persons with COPD typically are not.

Occupations at high risk of asbestos exposure

• Shipbuilders
• Insulation workers
• Construction workers (before 1990s)
• Plumbers
• Firefighters (older buildings that catch fire)
• Asbestos miners (don’t operate now)

Loeffler syndrome: It is characterized by eosinophilia and wandering lung shadows on CxR of unknown etiology. It presents with transient, mild, self limited respiratory symptoms. Ascariasis may be associated.

Atelectasis

• Collapse of lungs due to obstruction from malignancy, foreign body, mucous plugs, extrinsic compression, pleural effusions, tension pneumothorax, post-surgical, lack of surfactant
• Asymptomatic or dyspnea, cough, fever, chest pain
• Absent breath sounds
• Stopping smoking 6-8 weeks before surgery reduces risk in smokers
• Early ambulation after surgery, physiotherapy, CPAP and incentive spirometry reduces risk
• May cause pneumonia, respiratory failure

Clubbing

• Enlargement of finger tips with loss of normal angle between skin and nail plate
• Normally, diamond shaped area is seen when the back of the thumbs are apposed against each other. This space is obliterated in clubbing
• Congenital, familial or acquired from pulmonary disorders like malignancies, lung abscess, empyema, pneumoconiosis, cystic fibrosis, bronchiectasis, cyanotic heart disease, endocarditis, cor pulmonale, AV fistulas, cirrhosis, IBD, hyperthyroidism and hyperparathyroidism
• Advanced cases present with hypertrophic osteoarthropathy with painful periosteal proliferation of long bones, hyperhidrosis, paresthesia and muscle weakness

Kartagener syndrome or immotile cilia syndrome

• Primary ciliary dyskinesia and situs inversus
• Immotile or dysmotile cilia
• Internal organs like heart, liver, spleen are on the opposite side of the body (situs inversus)
• Presents with neonatal respiratory distress, frequent respiratory infections, sinusitis, otitis media, hearing loss, hydrocephalus and infertility, bronchiectasis
• AR inherited mutations causing defects in dynein genes DNAI1 and DNAH5
• Low exhaled nitric oxide (for screening), diagnosis confirmed by biopsy, electron microscopy and genetic testing