<B>Small Cell Carcinoma of Lung </B>

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Small Cell Carcinoma of Lung

Etiology:

• Associated with cigarette smoking.

Pathogenesis:

• BPDE (catabolite of benzo[a]pyrene in cigarette smoke) binds p53 mutational hot spots in lung carcinoma
• p53 mutation affects cell replication and centromere replication

Epidemiology:

• Increasing incidence with age, smoking history.
• More frequent in men than women.

General Gross Description:

• These neoplasms tend to be perihilar and surround large bronchi.
• Ill defined, grey white or hemorrhagic.
• May be far more extensive microscopically than grossly expected.

General Microscopic Description:

• Densely cellular "little blue cell" neoplasms.
• Fragile cells are easily crushed resulting in blue streaks.
• Almost no cytoplasm so nuclei appear molded to each other.
• Nuclei are so hyperchromatic and irregular that nucleoli are rarely visualized.
• Although there are fusiform, oat, and intermediate cell types, no difference in outcome.
• Dense core neurosecretory granules.
• May stain with chromagranin,neuron specific enolase, or synaptophysin.

Clinical Correlations:

• Highly aggressive neoplasms that frequently present with evidence of metastatic disease.
• Most likely to be associated with ectopic hormone product
• Central location associated with cough and hemoptysis
• Weight loss and dyspnea
• Staging depends on whether confined to one hemithorax
• Metastatic disease to lymph nodes, brain, liver and adrenal glands
• Treatment depends on chemotherapy.
• Overall two year survival 25%

References:
• Cotran RS, Kumar V, Robbins Sl. Robbins Pathologic Basies of Diseas. W.B. Saunders, 5 ed., Philadelphia, 1974, pp.720-725.