Pulmonology Book

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Sputum MicroscopyAka: Sputum Cytology, Sputum Gram Stain

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  1. See Also
    1. Sputum Collection
    2. Sputum Gross Exam
  2. Assessing Sputum Sample Quality
    1. Ideal Sputum Sample for Culture
      1. Under 10 squamous epithelial cell per low power field
      2. Many Neutrophils present (>5 per high power field)
      3. Bronchial epithelial cells present
      4. Alveolar Macrophages may be present
    2. Inadequate Sputum Sample
      1. Over 25 squamous epithelial cells/LPM
  3. Sputum Sample Preparation
    1. Pull strand or plug of Sputum onto slide
    2. Consider buffered crystal violet to stain cells
    3. Apply cover slip
    4. View under oil immersion
  4. Cytology Stains
    1. No Stain
      1. Blastomycosis
      2. Cryptococcosis
    2. Gram Stain
      1. Gram Positive Bacteria
      2. Candida
      3. Tuberculosis (weakly Gram Positive)
      4. Nocardia (weakly Gram Positive)
    3. Direct Fluorescent Antibody Staining
      1. Legionella
    4. Wright stain or Giemsa Stain
      1. Intracellular organisms
  5. Special Staining Circumstances
    1. Acid-fast Mycobacteria (Tuberculosis)
      1. Ziehl-Neelsen Stain (Red against blue background)
      2. Kinyoun stain
        1. Less reliable than Ziehl-Neelsen stain
        2. Results in quickly stained sample
      3. Fluorochrome dyes (auramine, rhodamine)
        1. Higher false positive rate than Ziehl-Neelsen stain
        2. Assist greatly in identifying organisms
    2. Fungal Organisms
      1. PAS staining or Methenamine silver staining
        1. Histoplasmosis
        2. Coccidioidomycosis
        3. Aspergillus
        4. Mucor
      2. KOH Preparation
  6. Microscopic findings
    1. Caseous masses
    2. Dittrich's plugs
    3. Curschmann's spirals (Asthma)
    4. Charcot-Leyden Crystals (Asthma)
    5. Bronchial casts
    6. Concretions
    7. Broncholith
      1. Calcified particles as seen in Broncholithiasis
    8. Lung Cancer cells
      1. Central bronchus tumors
      2. May require 4 samples to detect
    9. Eosinophils (>5%): identified with Wright's Stain
      1. Allergy
      2. Asthma

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