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Pleuritis with pleural effusion


Shah Dev, M.B.B.S.
Aliya N. Husain, M.D.

Last author update: 28 August 2025
Last staff update: 28 August 2025

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PubMed Search: Pleuritis with pleural effusion

Shah Dev, M.B.B.S.
Aliya N. Husain, M.D.
Page views in 2025 to date: 5,275
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Diagrams / tables | Clinical features | Diagnosis | Laboratory | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Gross images | Frozen section description | Frozen section images | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Positive stains | Negative stains | Molecular / cytogenetics description | Videos | Sample pathology report | Differential diagnosis | Practice question #1 | Practice answer #1 | Practice question #2 | Practice answer #2
Cite this page: Dev S, Husain AN. Pleuritis with pleural effusion. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pleurapleuritis.html. Accessed September 4th, 2025.
Definition / general
  • Pleuritis refers to inflammation of the pleura, which is often associated with pleural effusion and may result from a wide variety of causes, including infection, autoimmune disease, malignancy, metabolic conditions or drug reactions
Essential features
  • Pleuritis is an inflammatory process that involves the pleural surfaces and is often accompanied by pleural effusion
  • Etiologies include infection (bacterial, tuberculosis, fungal), autoimmune diseases (systemic lupus erythematosus [SLE], rheumatoid arthritis [RA], vasculitis), malignancy, uremia, drug induced injury and rare entities such as cryptogenic fibrosing pleuritis, xanthomatous pleuritis and immune checkpoint inhibitor associated pleuritis
  • Histologic patterns vary depending on underlying cause and include acute neutrophilic inflammation, chronic lymphoplasmacytic infiltrates, granulomatous inflammation and diffuse fibrosis
  • Diagnosis requires clinical correlation, imaging, pleural fluid analysis and in some cases, pleural biopsy or thoracoscopy
  • Radiologic features include effusions, pleural thickening, nodularity or loculations depending on the etiology
Terminology
  • Pleuritis
  • Pleurisy (historical)
  • Dry pleurisy (pleuritis without effusion)
  • Wet pleurisy (pleuritis with effusion)
  • Fibrinous pleuritis (or plastic pleuritis)
  • Adhesive pleuritis (chronic fibrosing pleuritis)
  • Serofibrinous pleuritis
ICD coding
  • ICD-10
    • A15.6 - tuberculous pleurisy
    • J90 - pleural effusion, not elsewhere classified
    • J91.0 - malignant pleural effusion
    • M32.13 - lung involvement in systemic lupus erythematosus
Epidemiology
  • No universal gender or age predilection overall; specific etiologies show characteristic demographic patterns
  • Geographic distribution depends on cause prevalence (e.g., tuberculous pleuritis is more common in tuberculosis [TB] endemic regions, such as South Asia [e.g., Pakistan and India], East Asia [China] and sub-Saharan Africa [e.g., Ghana, Mali, Benin]) (Curr Opin Pulm Med 2024;30:210)
Sites
Pathophysiology
  • In response to infection, inflammation, malignancy or autoimmune insult, the mesothelial lining of the pleura becomes activated, leading to increased vascular permeability, inflammatory cell infiltration and cytokine release, which lead to capillary leak, impaired lymphatic drainage and disruption of Starling forces, contributing to the accumulation of pleural fluid (pleural effusion)
  • Chronic or repetitive inflammation leads to pleural fibrosis, thickening and (in advanced cases) pleural adhesions (trapped lung)
  • Cause specific mechanisms
    • Bacterial infection (parapneumonic effusion, empyema): neutrophilic exudate with purulent collections possible (empyema)
    • Viral infection: lymphocyte predominant inflammation
    • Tuberculosis: granulomatous inflammation, delayed hypersensitivity, lymphocyte rich exudate (Respirology 2019;24:962)
    • Autoimmune pleuritis: immune complex deposition and vasculitis
    • Uremic pleuritis: retention of metabolic toxins in end stage renal disease leads to sterile fibrinous inflammation (Am J Kidney Dis 1987;10:19)
    • Drug induced pleuritis: hypersensitivity or immune mediated injury (immune checkpoint inhibitor associated pleuritis [e.g., atezolizumab] causes eosinophilic chronic inflammation) (Am J Case Rep 2021;22:e933396)
Etiology
Diagrams / tables

Images hosted on other servers:
Background, causes, symptoms and treatment

Background, causes, symptoms and treatment

Normal versus pleuritis and pneumothorax

Normal versus pleuritis and pneumothorax

Diagnostic / therapeutic algorithm for pleural effusion

Diagnostic / therapeutic algorithm for pleural effusion

Pathogenesis of lung involvement in SLE

Pathogenesis of lung involvement in SLE

Clinical features
  • General features (common to most causes)
    • Pleuritic chest pain (sharp, worsens with inspiration, coughing or movement), shortness of breath, dry cough, low grade fever and pleural friction rub (Am Fam Physician 2007;75:1357)
    • Large effusions: may cause orthopnea or positional discomfort
    • Systemic symptoms: fever, chills, malaise (especially in infectious causes); weight loss and night sweats (may suggest TB or malignancy)
  • Infectious pleuritis
    • Bacterial infections: acute presentation with high fever, chills, purulent effusion (empyema possible)
    • Tuberculous pleuritis: subacute onset of fever, chest pain and lymphocytic effusion; often accompanied by weight loss and night sweats (Respirology 2019;24:962)
  • Autoimmune associated pleuritis (J Clin Med 2022;11:6714)
    • Systemic lupus erythematosus (SLE): frequently presents with bilateral small to moderate effusions, sometimes the initial manifestation
    • Effusions may be serous or hemorrhagic; occasionally associated with pericardial involvement
      • Rare complication: hemopneumothorax
      • May occur as part of serositis triad (pleuritis, pericarditis, peritonitis)
    • Rheumatoid arthritis: recurrent, often exudative effusions; may progress to necrotizing pleuritis
  • Malignancy associated pleuritis: may be the initial presenting symptom and may produce large, recurrent or hemorrhagic effusions
  • Uremic pleuritis: may be asymptomatic or present with recurrent / persistent effusions (if symptomatic, symptoms improve with optimized dialysis or drainage) (Pediatr Pulmonol 2017;52:E52)
  • Cryptogenic fibrosing pleuritis: progressive exertional dyspnea, dry cough (may rapidly progress to hypercapnic respiratory failure and restrictive lung disease) (Intern Med 2022;61:2649)
Diagnosis
  • Clinical evaluation
    • Diagnosis is based on clinical presentation, imaging studies and pleural fluid analysis
  • Imaging studies
    • Chest Xray: initial imaging test; detects pleural effusions, thickening and calcifications
    • Ultrasound (US): highly sensitive for small effusions; assesses fluid characteristics (septations, loculations, echogenicity) and guides thoracentesis or biopsy (Open Access Emerg Med 2012;4:31)
    • CT scan (contrast enhanced): evaluates pleural thickening, lung parenchymal lesions, masses and mediastinal lymphadenopathy (Open Access Emerg Med 2012;4:31, Chest 2000;118:604)
    • MRI: provides soft tissue detail; helpful for evaluating fibrosis, chest wall invasion, diaphragm or pleural motion
    • PET CT: helpful for malignancy workup; increased FDG uptake often suggests malignancy or active inflammation
  • Procedures
Laboratory
  • Pleural fluid analysis (initial and essential laboratory test)
    • Most cases are exudative per Light's criteria (Am Fam Physician 2007;75:1357)
      • Pleural fluid protein / serum protein > 0.5
      • Pleural fluid lactate dehydrogenase (LDH) / serum LDH > 0.6
      • Pleural fluid LDH > two - thirds upper limit of normal serum LDH
    • Cell differential
    • Glucose: low in empyema, rheumatoid pleuritis, malignancy (Open Access Emerg Med 2012;4:31)
    • pH: < 7.2 suggests empyema or complicated parapneumonic effusion (Open Access Emerg Med 2012;4:31)
    • LDH: often elevated in exudates, markedly elevated in empyema or malignancy
    • Cytology: reactive mesothelial cells and mixed inflammation; malignant cells suggest neoplastic involvement
  • Infectious workup (if infectious etiology suspected)
    • Gram stain and bacterial cultures: standard for suspected bacterial infection
    • Acid fast bacilli (AFB) smear, culture and nucleic acid amplification (e.g., cartridge based nucleic acid amplification test [CB NAAT] for suspected tuberculosis) (Int J Mycobacteriol 2020;9:442)
    • Adenosine deaminase (ADA): elevated (> 40 U/L) supports TB pleuritis diagnosis (Respirology 2019;24:962)
  • Autoimmune workup
    • SLE: exudative effusion (with neutrophilic or mononuclear predominance), elevated LDH, low complement levels (C3, C4); positive ANA, anti-dsDNA (J Clin Med 2022;11:6714, Front Med (Lausanne) 2021;7:610257)
    • Rheumatoid arthritis: low glucose, low pH; rheumatoid factor (RF) often positive (J Cytol 2019;36:222)
    • ANCA associated vasculitis: positive ANCA serologies (granulomatosis with polyangiitis, microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis) (Chest 2021;160:572)
  • Malignancy workup
    • Pleural fluid cytology: detects malignant cells (sensitivity ~60%); cell block and immunohistochemistry may aid subtyping (e.g., distinguishing mesothelioma from metastatic carcinoma)
  • Other specific findings
    • Immune checkpoint inhibitor related pleuritis (e.g., atezolizumab): eosinophilic effusion, cytology negative for malignancy (Am J Case Rep 2021;22:e933396)
    • IgG4 related pleuritis: may demonstrate elevated serum IgG4 and IgG4+ plasma cells in pleural biopsy (J Med Case Rep 2021;15:241)
Radiology description
  • Chest radiograph (StatPearls: Pleural Effusion Accessed 8 July 2025], Open Access Emerg Med 2012;4:31)
    • Shows pleural effusion as blunting of costophrenic angles; large effusions may cause complete hemithorax opacification with mediastinal shift
    • May show pleural thickening and calcifications
  • Ultrasound (US) (Open Access Emerg Med 2012;4:31)
    • Distinguishes free versus loculated effusions; detects septations, fibrin strands and complex fluid collections (helpful in empyema)
  • Computed tomography (CT) (Open Access Emerg Med 2012;4:31)
    • Assesses pleural thickening, nodularity, masses, calcifications, fibrosis, chest wall invasion and underlying lung parenchyma
    • Helps distinguish benign smooth pleural thickening (seen in chronic inflammation) from nodular, asymmetric or circumferential thickening suggestive of mesothelioma
    • Split pleura sign indicates empyema (loculated, enhancing pleural layers)
  • Cause specific radiologic features
    • Tuberculous pleuritis: typically, moderate unilateral effusion; chronic cases may show pleural thickening, calcifications and sometimes passive collapse of adjacent lung (Respirology 2019;24:962)
    • Empyema: loculated collections with fibrous septations, enhancing pleural layers (split pleura sign) and possible air fluid levels
    • Lupus pleuritis: bilateral small to moderate effusions, sometimes hemorrhagic (J Clin Med 2022;11:6714)
    • Cryptogenic fibrosing pleuritis: bilateral pleural thickening, subpleural fibrosis, lung volume loss and consolidations (Eur J Case Rep Intern Med 2021;8:002498)
    • Immune checkpoint inhibitor associated pleuritis: persistent effusion on CT without mass or invasive disease; thoracoscopy may show normal appearing pleura despite ongoing effusion (Am J Case Rep 2021;22:e933396)
Radiology images

Images hosted on other servers:
Tuberculous pleuritis with trapped lungs

Tuberculous pleuritis with trapped lungs

Tuberculous pleuritis with lung infiltrates

Tuberculous pleuritis with lung infiltrates

Bilateral pleural effusions with basal consolidations

Bilateral pleural effusions with basal consolidations

Right sided pleural effusion with thick septations

Right sided pleural effusion with thick septations

Right pleural effusion with middle lobe consolidation

Right pleural effusion with middle lobe consolidation


SLE related HRCT lung abnormalities

SLE related HRCT lung abnormalities

Chest radiograph and computed tomography

Chest radiograph and CT

Large left pleural effusion and reduction after corticosteroid taper

Large left pleural
effusion and
reduction after
corticosteroid taper

Large left pleural effusion with pericardial fluid

Large left pleural effusion with pericardial fluid

Prognostic factors
  • Prognosis depends on the underlying etiology of pleuritis and pleural effusion
  • Favorable prognostic factors include self limited causes (e.g., viral pleuritis), prompt treatment of infectious and autoimmune conditions (e.g., bacterial pneumonia, lupus pleuritis) and nonmalignant etiologies such as infectious, autoimmune or uremic pleuritis, which typically have favorable outcomes (StatPearls: Pleurisy [Accessed 8 July 2025])
  • Unfavorable prognostic factors include malignancy associated effusions (e.g., mesothelioma, lung or breast cancer) with median survival often 1 - 1.5 years, delayed diagnosis or treatment (e.g., tuberculosis, empyema), development of chronic pleural fibrosis or trapped lung leading to restrictive lung dysfunction and recurrent effusions from unresolved or progressive underlying disease
Case reports
Treatment
  • General principles (StatPearls: Pleurisy [Accessed 8 July 2025])
    • Treatment is directed at the underlying cause (infectious, autoimmune, malignant, metabolic, drug induced or idiopathic)
    • Symptomatic relief with nonsteroidal anti-inflammatory drugs (NSAIDs) for pleuritic pain; opioids for severe cases
    • Therapeutic thoracentesis for large or symptomatic effusions and surgical management for those who don’t respond to nonsurgical measures
  • Infectious pleuritis
  • Autoimmune associated pleuritis
    • SLE: NSAIDs for mild cases; corticosteroids for moderate to severe cases; immunosuppressants or intravenous immunoglobulin (IVIG) for refractory disease (J Clin Med 2022;11:6714)
    • Rheumatoid arthritis: corticosteroids plus disease modifying antirheumatic drugs (DMARDs), such as methotrexate or hydroxychloroquine
  • Malignancy associated pleuritis (Eurasian J Med 2009;41:186)
    • Symptom management: therapeutic thoracentesis, pleurodesis (e.g., talc) or indwelling pleural catheter (IPC) for recurrent effusions
    • Definitive treatment based on tumor type: systemic chemotherapy, targeted therapy, radiation
    • Surgical options: pleurectomy or decortication may be considered for refractory or trapped lung
  • Uremic pleuritis (end stage renal disease): optimization of dialysis is crucial with thoracentesis for symptomatic relief; surgical management may be needed in severe refractory cases (Pediatr Pulmonol 2017;52:E52, Intern Med 2001;40:646)
  • Immune checkpoint inhibitor associated pleuritis: discontinuation of offending agent (corticosteroids may be effective in some cases and repeat thoracentesis may be required for recurrent effusions) (Am J Case Rep 2021;22:e933396)
  • Cryptogenic fibrosing pleuritis: high dose corticosteroids have variable efficacy and pleural decortication may be needed in cases of lung entrapment or progressive fibrosis (Eur J Case Rep Intern Med 2021;8:002498, Intern Med 2022;61:2649)
  • Xanthomatous pleuritis: treated surgically if secondary to pancreaticopleural fistula (J Bronchology Interv Pulmonol 2022;29:155)
Clinical images

Images hosted on other servers:
Surgical view of biliopleural fistula

Surgical view of biliopleural fistula

Diffuse, yellow, plaque-like pleural deposits

Diffuse, yellow, plaque-like pleural deposits

Gross description
  • Pleural effusion appearance: fluid may be serous, turbid, purulent (thick, yellow-green with fibrin strands in bacterial infections), serosanguineous or hemorrhagic (in malignancy, pulmonary embolism or lupus) or chylous (milky fluid accumulation in thoracic duct obstruction)
  • Pleural surface findings
    • Pleura is typically thickened, opaque, dull and fibrotic, especially in chronic or recurrent inflammation
    • Fibrinous exudate may coat pleural surfaces in early or active pleuritis, producing a shaggy (bread and butter) appearance (Autops Case Rep 2016;6:5)
    • Fibrous adhesions between parietal and visceral pleura are common in organizing or chronic stages, sometimes leading to lung entrapment (trapped lung)
    • Calcifications or pleural plaques may develop in longstanding pleuritis, particularly with prior asbestos exposure or chronic tuberculosis
    • Nodularity or plaque-like thickening may suggest malignancy or prior asbestos exposure
    • Extensive pleural fibrosis may contribute to restrictive lung disease (Intern Med 2022;61:2649)
  • Cause specific gross features
    • Tuberculous pleuritis: multiple small nodules or plaques on pleural surfaces; may contain caseous necrosis (J Clin Med 2022;11:6714)
    • Empyema: loculated, organized pus with fibrous septations and thickened pleural rind
    • Malignancy associated pleuritis: irregular pleural thickening, nodularity or mass lesions involving parietal and visceral pleura
    • Cryptogenic fibrosing pleuritis: dense fibrous thickening with firm adhesions; entrapped lung may be seen (Intern Med 2022;61:2649)
    • Xanthomatous pleuritis: yellow-tan plaques or nodular thickening with lipid laden areas (J Bronchology Interv Pulmonol 2022;29:155)
  • Associated findings
    • Lung may demonstrate atelectasis, consolidation or organization if underlying pneumonia or pulmonary involvement is present
Gross images

Images hosted on other servers:
Gross pleural and pulmonary findings (tuberculosis)

Pleural and pulmonary findings (tuberculosis)

Bread and butter pleuritis

Bread and butter pleuritis

Frozen section description
  • Frozen section may show fibrinous exudate overlying the pleural surface with variable inflammatory infiltrates, depending on etiology
  • Acute cases show dense neutrophilic infiltrates (e.g., empyema, parapneumonic effusion)
  • Chronic cases show fibrosis with lymphoplasmacytic infiltrates, granulation tissue and vascular proliferation
  • Granulomatous inflammation may be seen in tuberculosis or fungal infections
Frozen section images

Contributed by Aliya N. Husain, M.D.
Organizing pleuritis

Organizing pleuritis

Inflammation in muscle

Inflammation in muscle

Microscopic (histologic) description
  • Common histologic features
    • No universally accepted histologic diagnostic criteria or WHO classification system exist
    • Diagnosis relies on identifying the predominant inflammatory pattern and correlating with clinical and laboratory findings
    • Variable degrees of inflammatory cell infiltration depending on etiology
    • Acute inflammation: dense neutrophilic infiltrate, fibrin deposition and exudate (seen in bacterial / parapneumonic pleuritis, empyema)
    • Chronic inflammation: lymphoplasmacytic infiltrates, fibrosis and pleural thickening (seen in viral, autoimmune, uremic, idiopathic cases)
    • Granulomatous inflammation: well formed granulomas with or without central caseation (suggestive of tuberculosis or fungal infections)
    • Fibrinous pleuritis: thick fibrin layers over pleural surfaces with minimal cellular infiltration (seen in early serositis or uremic pleuritis)
  • Cause specific histologic patterns
    • SLE: fibrinous exudate with mixed neutrophils and mononuclear cells; vasculitis may occur with fibrinoid necrosis (J Clin Med 2022;11:6714)
    • Rheumatoid arthritis: necrotizing granulomas, fibrinoid necrosis, rheumatoid nodules
    • ANCA associated vasculitis: small vessel vasculitis, neutrophilic infiltration, fibrinoid necrosis
    • Tuberculosis: granulomas with caseous necrosis; acid fast bacilli may be identified (Int J Mycobacteriol 2020;9:442)
    • Fungal infections: granulomatous inflammation; fungal organisms highlighted by PAS or GMS
    • Eosinophilic pleuritis: ≥ 10% eosinophils; seen in drug induced, parasitic or air / blood exposed pleuritis (Curr Opin Pulm Med 2003;9:254)
    • Cryptogenic fibrosing pleuritis: diffuse pleural fibrosis with collagen deposition, fibroblastic foci, mesothelial cell entrapment; organizing pneumonia may be seen in adjacent lung (Intern Med 2022;61:2649)
    • Xanthomatous pleuritis: aggregates of foamy macrophages, chronic inflammation, multinucleated giant cells (J Bronchology Interv Pulmonol 2022;29:155)
    • Immune checkpoint inhibitor associated pleuritis: lymphoplasmacytic infiltrate, scattered eosinophils, reactive mesothelial hyperplasia, variable fibrosis and fibrinoid necrosis (Am J Case Rep 2021;22:e933396)
  • Rare and distinctive patterns
    • Reactive mesothelial hyperplasia may be present across multiple causes but lacks cytologic atypia
    • Fibroblastic proliferation, capillary neovascularization and organizing fibrin may be seen in chronic or resolving stages
Microscopic (histologic) images

Contributed by Aliya N. Husain, M.D.
Fibrinous exudate

Fibrinous exudate

Necrotizing granuloma

Necrotizing granuloma

Eosinophilic infiltrate

Eosinophilic infiltrate


Neutrophilic inflammation

Neutrophilic inflammation

Zonation of fibrosis

Zonation of fibrosis

Mesothelial proliferation

Mesothelial proliferation


Granulation and fibrosis

Granulation and fibrosis

Dense pleural fibrosis

Dense pleural fibrosis

Pleural plaque

Pleural plaque

Cytology description
  • Pleural fluid cytology is essential in evaluating any pleural effusion, especially to distinguish between benign (inflammatory / reactive) and malignant etiologies (Eur Respir J 2018;52:1801254, Thorax 2023;78:32, StatPearls: Pleural Effusion Accessed 8 July 2025])
  • Cytologic features in benign pleuritis
    • Reactive mesothelial cells, which may show enlarged nuclei and prominent nucleoli but lack overt atypia
    • Mixed inflammatory background, often depending on underlying etiology
  • Malignant pleural effusion cytology
    • Malignant cells may be seen in metastatic carcinomas, mesothelioma and lymphomas
    • Sensitivity of pleural fluid cytology for detecting malignancy is ~60%; repeated sampling increases diagnostic yield (Thorax 2023;78:32)
Positive stains
Negative stains
Molecular / cytogenetics description
  • Mesothelioma versus reactive pleuritis: BAP1 loss (IHC) or CDKN2A / p16 deletion (FISH) specific for malignancy; present in most of the mesotheliomas and absent in benign pleuritis (Am J Surg Pathol 2016;40:120)
  • Carcinoma molecular testing: EGFR, ALK and KRAS mutations testable on fluid cell block and guide targeted therapy
Videos

Causes and symptoms of pleuritis

Tutorial on pleural pathology

Animated explanation of pleuritis


Cytology: histology correlation in pleural fluid

Overview of pleural effusion causes and treatment

Sample pathology report
  • Pleura, biopsy:
    • Chronic fibrosing pleuritis with mild chronic inflammation (see comment)
    • No evidence of malignancy
    • Comment: The biopsy shows dense collagen deposition with scattered chronic inflammatory cells.
Differential diagnosis
Practice question #1


A 58 year old immunocompetent man from South Asia presents with low grade fever, chronic cough, pleuritic chest pain and weight loss. Imaging reveals moderate unilateral pleural effusion and pleural thickening. Thoracentesis yields lymphocyte predominant exudate. A thoracoscopic pleural biopsy reveals the histologic appearance shown in the image. Which of the following special stains is most sensitive and specific for confirming the diagnosis in this setting?

  1. Grocott-Gomori methenamine silver (GMS)
  2. Mucicarmine
  3. Periodic acid-Schiff (PAS)
  4. Trichrome
  5. Ziehl-Neelsen (ZN)
Practice answer #1
E. Ziehl-Neelsen (ZN). Ziehl-Neelsen stain is the most specific and widely used stain for acid fast bacilli (including Mycobacterium tuberculosis) and is essential for confirming tuberculosis (TB) in necrotizing granulomas. Answer A is incorrect because GMS highlights fungi (e.g., Histoplasma, Cryptococcus), not mycobacteria. Answer B is incorrect because mucicarmine is used for the capsular material of Cryptococcus neoformans, not TB. Answer D is incorrect because trichrome stains collagen and is used for fibrosis, not infectious organisms. Answer C is incorrect because PAS stains fungal organisms and mucopolysaccharides but not acid fast bacilli.

Comment Here

Reference: Pleuritis with pleural effusion
Practice question #2
A 70 year old woman presents with recurrent pleural effusions and nonresolving pleuritic chest pain. Thoracentesis reveals an exudative effusion with a mixed inflammatory infiltrate. A pleural biopsy demonstrates diffuse fibrosis with chronic inflammatory cells but no cellular atypia. The pathologist is considering the differential diagnosis of fibrosing pleuritis versus low grade desmoplastic mesothelioma. Which of the following histologic features would most favor a diagnosis of desmoplastic mesothelioma rather than benign pleuritis?

  1. Dense collagen deposition without associated atypia
  2. Lung parenchymal invasion by atypical spindle cells
  3. Patchy pleural fibrosis with focal lymphocytic aggregates
  4. Presence of interstitial macrophages with hemosiderin deposition
  5. Subpleural fibroblast proliferation with preserved mesothelial basement membrane
Practice answer #2
B. Lung parenchymal invasion by atypical spindle cells. Lung parenchymal invasion is a defining feature of desmoplastic mesothelioma and is not present in benign pleuritis. The presence of atypical spindle cells infiltrating into lung tissue is a key diagnostic clue that supports a diagnosis of malignancy. Answer C is incorrect because patchy pleural fibrosis with focal lymphocytic aggregates is more consistent with chronic pleuritis rather than a malignant process. Answer E is incorrect because basement membrane preservation is a hallmark of benign reactive processes and argues against malignancy. Answer D is incorrect because hemosiderin laden macrophages are nonspecific and can be seen in benign and inflammatory conditions. Answer A is incorrect because while fibrosis is seen in both pleuritis and desmoplastic mesothelioma, the presence of atypia and invasion distinguishes malignancy.

Comment Here

Reference: Pleuritis with pleural effusion
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