Squamous cell carcinoma accounts for ~30-35% of all lung cancers and in most instances is due to heavy smoking.
Central tumors with invasion and obstruction of bronchi typically result in the distal collapse which may have superimposed infection. Chronic cough and hemoptysis may be present.
Metastatic disease may be the first sign of malignancy. Four subtypes are recognized 4:
Papillary
Clear cell
Small cell (not to be confused with small cell lung cancer)
Basaloid
Radiographic Features:
LUL collapses anterior and superior:
Faint veiling opacity on the frontal
Obliteration of the aortic arch by the collapsed apicoposterior segment
Displacement of the major fissure and filling in of the anterior clear space on the lateral
Indirect Signs:
Elevation of the diaphragm
Juxtaphrenic peak
Hilar displacement
Mediastinal shift
Narrowing of rib interspaces
Compensatory Hyperaeration
“Luftsichel” sign: crescentic lucency formed by the superior herniation of the hyperinflated superior segment left lower lobe.
Differential Diagnosis:
Depends on the location of the lesion:
Hilar masses eg lymph nodes if the lesion is central in position
Solitary pulmonary nodule differential if it is peripheral location
Pearls:
squamous carcinomas are encountered more frequently in male smokers.
The appearance of CT can be variable, depending on whether it is central or peripheral in location.
