Respiratory System

• Different specimen types for lung/respiratory tests:

  - Sputum - Bronchial brushings - Washings - Bronchoalveolar lavage - FNA
• Upper Respiratory Tract

  • mouth
  • nose
  • sinus
  • throat
  • larynx
  • trachea
• Histology of Upper RT

  • stratified squamous epithelium
  • complex layer of glandular epithelium
• Cells in respiratory epithelium

  • reserve cells
  • Feyrter or K cells
• Lower Respiratory Tract

  • Bronchioles
  • terminal Bronchioles
  • Alveolar
• Bronchioles


  lined by a single layer of non-ciliated columnar cells and goblet cells.

  Clara cells - tall columnar cells produce surfactant
• Terminal Bronchioles


  Lined by low columnar epithelium

  solely involved in air conduction and involved in gaseous exchange

  • lining then becomes cuboidal and merges with flattened epithelial cells in alveolar ducts -> alveolar sacs partioned into alveoli
• Respiratory Cytopathology Techniques


  Sputum, Bronchial Brushings, Washings, Bronchoalveolar lavage, FNA
• Calcific Blue Bodies and Corpora Amylacea

  • Seen In Chronic Lung Disease
  • Calcium Carbonate with central birefringence
  • Corpora Amylacea - non-calcified round structures of glycoproteins including amyloid
  • pale pink, congo red +ve, birefringence
• Psammoma Bodies

  • laminated retractile calcified concretions
  • sometimes found in malignancy - not necessarily associated
• Ferruginous Bodies

  • filamentous dust particles aka Asbestos coated with protein and iron.
  • 5-200um in length, light brown in colour.
  • Blue on Perl's Prussian stain for Iron
• Inflammatory Diseases of the Lung

  • Bacterial Pneumonia
  • Pulmonary Tuberculosis
  • Epithelioid Histiocytes - elongated macrophages, pale cytoplasm and no digested material
  • Langhan's Giant Cells
  • only seen on FNA but characteristic of disease
  • 2-10x size of a mononuclear macrophage
  • up to 100 ovoid nuclei at one pole of cell
  • cytoplasm amphophilic (stains with acid or basic dye)
• Viral Infections of the Lung

  • Herpes Simplex Virus
  • Varicella Zoster
  • Adenovirus
  • Measles
• Parasitic Infections

  • Protozoa
  • Nematodes (round worms)
  • Trematodes (Flukes)
  • Cestodes (tapeworms)
  • Arthropods (Insects/spiders)
  • Leeches
• Cryptococcus


  Fungus pathogenic to humans, if disseminated leads to CNS involvement and Meningitis
• Pneumocystis Jiroveci (PCP)


  Fungus wide spread in soil and atmosphere, inhalation -> pneumonia in immunocompromised patients (AIDS and transplants)
• Asthma


  • Mucous plugs in BAL
  • Curschmann spirals
  • Inflammatory debris with eosinophils and Charcot Leyden Crystals
  • Bronchial epithelial cells can be papillary shaped with well-defined borders called Creola Bodies
• COAD - Chronic Obstructive Airways Disease


  Chronic bronchitis and emphysema -> smoking
• Chronic bronchitis


  • Presence of hypertrophy of mucous glands and increased sputum produced
• Oncogenic Effect of Asbestos

  • crocidolite/blue asbestos most oncogenic
  • asbestos fibres cause genetic change in target cells
  • fibres <5um can be cleared without disease
  • long fibres >8um long and 0.15um wide most oncogenic
  • high incidence of mesothelioma after asbestos exposure but depends on type and duration exposed
  • 80% of malignant mesothelioma
• Adenocarcinoma

  • primary & secondary
  • most common primary sites:
  • colon
  • prostate
  • breast
  • bladder
  • kidney
  • CK7 and TTF1 +ve & CK20 -ve
  • Diff Diagnosis in poorly differentiated adenocarcinoma includes Small Cell carcinoma and Large cell carcinoma
  • Diff diagnosis in well differentiated = atypical adenomatous hyperplasia & epithelioid mesothelioma
• Small Cell Carcinoma (SCC)

  • Location, Aetiology and Prognosis
  • central or hilar position
  • Rapid growth
  • disseminates widely
  • very poor prognosis
  • chemo improves survival time
  • Morphology
  • groups of small dissociating tumour cells
  • scant cytoplasm
  • irregular moulding nuclei
  • coarse stippled chromatin
  • inconspicuous nucleoli
  • degeneration
  • Cells are only 2-3 x size of lymphocyte
  • Problems
  • metastatic breast cancer
  • prostate
  • malignant lymphoma