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Squamous Carcinoma of Lung

Etiology: • Most closely associated with cigarette smoking of all lung cancers • Radiation, air pollution and genetic predisposition may also play a role

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 • Sequence of changes from squamous metaplasia to dysplasia to carcinoma in situ and then invasive carcinoma seen.

Epidemiology: • Accounts for up to half of all lung cancers. • Up to 10% of long term cigarette smokers develop

General Gross Description: • Usually arises from a major bronchus resulting in a central rather than a peripheral location • Gray white hard granular neoplasm • Central cavitation common in large cancers • Uninvolved lung may often show emphysema or other smoking related pathology

General Microscopic Description: • Composed of cells with large irregular nuclei • Coarse nuclear chromatin with large nucleoli • Cells arranged in sheets • May make keratin pearls • Intercellular bridges considered diagnostic

Clinical Correlations: • Central location associated with cough and hemoptysis • Weight loss and dyspnea • Staging dependent on extent of disease ranging from I (confined to the lung with >2 cm distance from hilum and pleura) to IV (metastatic disease) • Metastatic disease to lymph nodes, brain, liver and adrenal glands • Surgical treatment is preferred; many patients have insufficient pulmonary reserve for surgery; radiation an alternative • Overall five year survival 10%

References: • Cotran RS, Kumar V, Robbins SL. Robbins Pathologic Basis of Disease. 5th edition. W.B. Saunders. Philadelphia 1994. pp.720-25.