Definition/General

Introduction:
-Malignant pleural effusion represents accumulation of neoplastic cells in the pleural space
-It accounts for 15-20% of all pleural effusions
-Most commonly results from metastatic adenocarcinoma
-Lung and breast are the most frequent primary sites.
Origin:
-Results from direct pleural involvement by tumor
-Lymphatic obstruction by malignant cells
-Increased vascular permeability
-Decreased lymphatic drainage
-May be due to primary pleural malignancy (mesothelioma).
Classification:
-Classified based on primary tumor type
-Adenocarcinoma (most common)
-Squamous cell carcinoma
-Small cell carcinoma
-Large cell carcinoma
-Mesothelioma
-Hematological malignancies.
Epidemiology:
-Malignant effusions represent 50% of exudative pleural effusions
-Peak incidence in 6th-7th decades
-Lung cancer (35-40%)
-Breast cancer (20-25%)
-Ovarian cancer (5-10%)
-Lymphoma (10-15%).

Clinical Features

Presentation:
-Progressive dyspnea (most common)
-Chest pain (pleuritic or dull)
-Persistent cough
-Fatigue and weakness
-Weight loss
-Night sweats
-Massive effusion causing respiratory distress.
Symptoms:
-Dyspnea on exertion progressing to rest
-Chest heaviness or pressure
-Dry cough
-Orthopnea
-Reduced exercise tolerance
-Constitutional symptoms (fever, weight loss, anorexia).

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Gross Description

Microscopic Description

Immunohistochemistry

Molecular/Genetic

Differential Diagnosis

Sample Pathology Report

Template Format

Sample Pathology Report

Complete Report: This is an example of how the final pathology report should be structured for this condition.

Specimen Information

Pleural fluid, [volume] mL, [appearance]

Fluid Analysis

Protein: [level] g/dL, LDH: [level] U/L, [exudative/transudative]

Cellularity

Cellularity: [high/moderate/low], [predominant cell type]

Morphological Features

Shows [architectural pattern] with [nuclear features]

Cellular Atypia

Nuclear atypia: [mild/moderate/severe], pleomorphism: [present/absent]

Background

Background shows [inflammatory cells/blood/debris]

Immunohistochemistry

[Marker]: [positive/negative], suggests [primary site/cell type]

Primary Site Assessment

Immunoprofile consistent with [primary site] origin

Staging Implications

Indicates [M1a/M1b] disease, Stage [IV]

Final Diagnosis

Final diagnosis: Malignant effusion, [cell type], consistent with [primary site] origin