Malignant Effusion, Carcinomas

Malignant Effusion, Carcinomas
Donna M. Coffey, MD
Key Facts
Clinical Issues
  • ˜ 30% of all body fluids are malignant effusions
  • Carcinomas account for > 95% of malignant effusions in adult patients
  • Diagnosis of malignancy in a body fluid is indicative of a high-stage tumor
    • Grim prognosis
  • Cytology is a cost-effective and accurate method for detecting malignancy in effusion with overall sensitivity of 58-71% and specificity close to 100%
Cytopathology
  • Key feature is presence of a dual population of tumor cells with background mesothelial and inflammatory cells
  • Malignant cells on cell block form tight clusters, papillae, or acini sometimes situated in an empty space or lacunae
  • Architecture and nuclear features on cytology preparations correlate with cell block findings and, in most cases, with histology of primary neoplasm
Top Differential Diagnoses
  • Benign effusions secondary to infections, therapy effect, trauma, or metabolic disorders have reactive mesothelial cells with atypia worrisome for malignancy
  • Differential diagnosis with malignant mesotheliomas requires a panel of immunohistochemical stains
  • Poorly differentiated carcinomas can shed in a dispersed single cell pattern resembling large cell lymphomas
Pap stain of pleural fluid shows dense spherical groups or morulae of metastatic ductal adenocarcinoma. Clusters and spheres of metastatic adenocarcinoma have smooth cell borders.
Pap stain of pleural fluid shows numerous single lobular breast carcinoma cells. The tumor cells are relatively small and uniform with some containing intracytoplasmic mucin droplets.
CLINICAL ISSUES
Presentation
  • ˜ 30% of all body fluids are malignant effusions
  • Carcinomas account for > 95% of malignant effusions in adult patients
  • Most patients have a known primary neoplasm or multiple primary tumors
    • Malignant effusion is the 1st manifestation of an occult primary in up to 17% of patients
  • Cytology is a cost-effective and accurate method for detecting a malignancy in an effusion
    • Sensitivity for diagnosing malignancy ranges 58-71%
    • Repeated taps increase detection rate by almost 30%
    • Specificity of cytologic diagnosis is almost 100%
      • Rate of false-positive diagnosis is < 1%
      • Most occur in cases with marked mesothelial cell atypia
  • Adenocarcinomas account for 60-65% of pleural and pericardial and 80% of peritoneal malignant effusions
    • Breast cancer: Most common primary in malignant pleural/pericardial effusions in females
    • Lung cancer: Most common primary in malignant pleural/pericardial effusions in males and 2nd most common in females
  • Squamous cell carcinomas account for 2-4% of all malignant effusions
    • Most are poorly differentiated carcinomas from lung, cervix, or esophagus
  • Small cell carcinomas account for 4% of pericardial and 2-9% of malignant pleural effusions
Prognosis
  • Diagnosis of malignancy in a body fluid is indicative of a high-stage tumor with poor prognosis
  • Median survival for patients with a positive effusion is < 6 months
CYTOPATHOLOGY
Cellularity
  • Malignant effusions are usually highly cellular
    • Cellularity persists in repeated taps
Pattern
  • Adenocarcinomas exfoliate as large cohesive clusters or spheres with smooth cell borders, papillary fragments, or dispersed single cells
  • Squamous cell carcinomas present as single cells, sheets, or cohesive clusters
  • Small cell carcinomas exfoliate as single cells, short chains, or small tight clusters of tumor cells
Background
  • Variable amount of inflammatory cells ± necrotic debris
    • Background mucin and foamy macrophages in cases of pseudomyxoma peritonei
    • Psammoma bodies can be seen in carcinomas with papillary architecture (i.e., ovarian serous carcinoma, lung, thyroid, mesotheliomas)
      • Psammoma bodies are not diagnostic of malignancy as they can also be seen in endosalpingiosis or mesothelial hyperplasia
    • Squamous and small cell carcinomas often have karyorrhectic debris
      • Anucleated squamous cells are often present in squamous cell carcinomas
Cells
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Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Malignant Effusion, Carcinomas

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