pleura and mediastinal pathology Flashcards
Pleural effusion
Accumulation of fluid (>15 ml) in the pleural space secondary to: increase in hydrostatic pressure–> transudate (CHF,lymphatic blockage via tumor)
Decreased osmotic pressure –> transudate (nephrotic syndrome, cirrhosis, malnutrition)
Increased vascular permeability-> exudate (pneumonia)
Transudate vs Exudate
transudate: extracascular fluid that has a low level of protein, low specific gravity, and low cellularity
Due to increased hydrostatic pressure or decreased oncotic pressure
Exudate: extravascular fluid that has a high level of protein, high level of protein high specific gravity and increased cellularity, due to vascular permeability
Pleural effusion clinical presentation:
Dyspnea, pleuritc pain and cough, enlarged hemithorax, dullness on percussion, decreased or absent breath sounds, compression of the lung( atelectasis leading to repiratory distress
Management: CXR, thoracocentesis, analysis of pleral fluid, chemisty, culture, cytology, pleural biopsy (percutaneous, open), treatment of underlying cause)
Common causes of pleural effusion
Infections: bacterial pneumonia, viral disease, TB
Pulmonary embolism, malignant neoplasm, trauma
Systemic conditions: CHF, cirrhosis, Nephrotic syndrome collagen vascular diseases
pleural effusions types
Inflammatory pleural effusions: serofibrinous suppurative(empyema), hemmorrhagic
Non - inflammatory pleural effusions: hydrothrox, hemothroax, chylothorax
Inflammatory pleural effusions
serous, fibrinous, and serofibrinous: inflammatory condtions such aspneumonia, TB lung infarcts and abcesses
Purulent exydate: empyema: localized accumulation of pus due to organsims,
Hemorrhagic pleurits: coagulopathies, rickettsial disease, malignant neoplasms
Empyema (pyothorax)
Purulent pleural effusions complicating lung infections (Pneumococci, staphilococci, and streptococci)
Suppurative pleuritis
Pleural surface is coated by shaggy thick fibrin lung infections (pneumococci, staphilocci and streptococci) with green purulent exudate
Organization produces adhesions and loculation circumscribing the pus and limiting lung expansion
Surgical decotrication is treatment of choice
Non inflammatory effusions
Hydrothorax: clear serous fluid (cardiac failure, pulmonary congestion and edema, cirrohosis, uremia, renal failure
Hemothrorax: hemorrhagic fluid: ruptured aortic aneurysm, trauma
Chylothorax: milky fluid (thoracic ducuts trauma, or lymphatics occlusion secondary to malignancy)
Pneumothorax
Presence of air or gas within the pleural cavity
Spontaneous- traumatic- therapeutic
Mostcommonly associated with emphysema, asthma and tb
Spontaneous idiopathic pneumothorax: encountered in young individuals secondary to rupture of spall apical blebs the trachia is deviated to the ipsilatereal side, usually subsides spontaneously
Tension pneumothorax: when the defects acts as a flap that permits entrance of air during inspiration but doesnt allow escape of air during expiration
Pneumothorax mechanism
Perforation of the visceral pleura and entry of air from the lung
Penetration of air from the chest wall, diaphragm, mediastinum or esophagus, gas forming organisms in empymea
clinical symptoms of pneumothorax
Chest pain, dyspnea, absent breath sounds on ausultation
Tympanitic percussion (hyper resonance) Contralateral deviation of the trachea on CXR, compression and collapse of lung parenchyma with atelactasis, marked respiratory distress
Spontaneous pneumothorax
may be idiopathic (unknown cause), secondary to rupture of pleural bleb or bulla, bronchopleural fistula, bullous emphysema
Tension pneumothorax
Due to penetrating trauma to the lungs, produces increased pleural cavity pressure with compression and atelectasis, flap like pleural defect acts like a valve allowing air in but not out
Sudden onset of respiratory distress (medical emergency)
Trachea deviated to contralateral side of pneumothorax
Pleural neoplasms
benign: solitary fibrous tumor (pleural fibroma)
Malignant: metastases from other organs, malignant mesothelioma
Solitary fibrous tumor
Soft tissue (mesenchymal) tumor Polypoid, well circumscribed, pedunculated,
Composed of fibroblasts with abundant collagenized stroma, microscopic appearance: spindle cells
Benign tumor, cured by simple excision
Mostly asymptomatic and discovered incidentally on chest X rays
Associated with hypoglycemia and clubbing of the fingers
malignant mesothelioma
neoplastic proliferation of mesothelial cells ligning serosal surface, most common in adults over 50
Asbestos exposiore, radiotion, chronic inflammation, viral infections, idiopathic
Asbestos related mesothelioma: epidemiologic studies (coastal areas), lifetime risk for devloping mesothelioma is up to 10% in pts with a history of heavy exposure, long latency period (20-40 yrs), occupational exposure millworkers, roofing material textiles, insulation, shipyard workers
Insidious slow growing neoplasms, recurrent pleural effusions, chest pain and dyspnea, 20% pts have fibrosis, fatal malignancy
malignant mesothelioma pathology
Tumor characteristically spread along mesothelial surface, composed of bland appearing cuboidal cells (well-differentiated neoplasm)
Very difficult for pathologist to distinguish mesothelioma from metastatic carcinoma to the pleura
Can also involve other serosal surfaces
metastatic tumors
Metastatic tumors are more common than primary malignancies in the pleura
Lung is the most frequent source of metasteses to the pleura, other tumors include breast and avarian cancer, pancreas, kidney
Spread is by blood, lymphatics or direct extension
Mets are often multiple and bilatera
inflammation of the mediastinum
Acute mediastinits (complication of conditions affecting neighboring organs, esophageal perforation, perforation of lung abcess, sternal osteomyelitis)
Granulomatous mediastinatis (chronic disorder secondary to fungal or mycobacterial infection)- Histoplasmosis, tuberculosis, crytococcosism atypical mycobacteria, aspergillosis
Idiopathic scelrosing mediastinitis (unknown etiology)
Congenital cysts: Usually unilocular, children aged 5- 15 years, lined by simple cuboidal epithelium, may be filled with serous fluid
myasthenia gravis
May be associated with thymic lesions- thymic hyperplasia, thymoma, thymic carcinoma
Auto- anti bodies form to acetylcholine receptors in neuromuscular junction
Autosenstization to AChR is initiated in the thymus due to defective confrontation of Ach-secreting thymic myoid cells with T cells
Symptoms: weakness, fatigability, ptosis, diplopia`
Thymic hyperplasia
Thymic lymphoid follicular hyperplasia: associated with myasthenia gravis and other autoimmune disorder
Tumors of the mediastinum
Posterior: Neruogenic tumors (Schwannoma, neurofibroma, ganglioneruoma, neuroblastoma)
Middle: (metastatic tumors, pericardial cyst, bronchogenic cyst, lymphomas)
Anterior-Superior: Metastatic tumors, thymoma thymuc CA, lymphomas, germ cell tumors, sarcomas, congenital thymic cysts
Thymoma
Neoplastic proliferation of thymic epithelial cells
usually contains lots of immature T cells (non neoplastic) frequently associated with MG and other paraneoplastic syndromes
May be composed of spindle cells or round epithelioid cells, slow growing tumor that may recur but rarely mets
Symptoms: asymptomatic in 30%, cough, dyspnea, chest pain, SVC syndrome, paraneoplastic syndromes, myasthenia gravis, pure red cell aplasia, hypogammaglobinemia, agranulocytosis, white blood cell aplasia, polymyositis sle, pemphigus vulgaris disseminated herpes, spindle cells A and round cells B and AB
Clincal behavior: depends on the status of the capsule, encapsulated tumors are cured by complete surgical exxcision, invasice tumors tend to recur repeatedly and may eventually metastasize, recurrent tumors may progress to thymic carcinoma
thymic carcinoma
Resemble other types of carcinoma occuring in other organs (squamous small cell, adenocarcinoma), most are sqaumous cell carcinomas, diagnosis of exclusion (there are no specific features that permit definit histologic diagnisis)
