Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (593 page)

   
Large cell undifferentiated carcinoma
: Rapidly growing cancer forms near the surface or outer edges of the lungs.

   Who Should Be Suspected?

   Heavy cigarette smokers who have new onset of cough, a change in the characteristics of a preexisting cough, and the presence of hemoptysis should be considered; cancer may be the cause of cough.

   Typical symptoms of lung cancer in the chest include persistent cough; pain in the chest, shoulder, or back unrelated to pain from coughing; a change in color or volume of sputum; shortness of breath, changes in the voice; harsh sounds with each breath; and recurrent lung problems such as bronchitis, pneumonia, and hemoptysis.

   Diagnostic Findings

   The diagnosis of lung cancer is primarily based on evaluation of individuals with symptoms. Screening for lung cancer is not widely used, since no screening test (chest radiography, sputum cytology, or CT) has been shown to reduce mortality from lung cancer.

   Diagnostic tests should include physical and chest examination, chest x-ray, CT, positron emission tomography (PET) and spiral CT scan, MRI, sputum cytology, bronchoscopy, and biopsy. Cytologic examination of spontaneously expected or induced sputum may provide a definitive diagnosis of lung cancer. Bronchoscopy is usually indicated when there is a suspicion of airway involvement by a malignancy.

   Molecular diagnostic tests for non–small cell lung cancer (NSCLC) included EGFR, and KRAS mutations are important for proper therapy selections.

   Anaplastic lymphoma kinase (ALK) gene rearrangements to identify a subset of patients with NSCLC and specific treatment with ALK inhibitors.

Suggested Readings

Bach PB, Silvestri GA, Hanger M, et al. Screening for lung cancer. ACCP Evidence-Based Clinical Practice Guidelines.
Chest.
2007;132:69S–77S.

Kvale P. Chronic cough due to lung tumors.
Chest.
2006;129:147S–153S.

Rivera M, Detterbeck F, Mehta AC. Diagnosis of lung cancer, the guidelines.
Chest.
2003;123:129S– 136S.

EVALUATION OF PLEURAL EFFUSIONS

   Definition

Pleural effusion is defined as increased amount of fluid in the pleural cavity. The underlying cause of an effusion is usually determined by first classifying the fluid as an exudate (e.g., infections, malignant, drug reactions) or a transudate (e.g., CHF, cirrhosis, atelectasis, nephritic syndrome).

   Exudates are fluids, cells, or other cellular substances that are slowly discharged from blood vessels, usually from inflamed tissues.

   Transudates are fluids that pass through a membrane or squeeze through tissue or into the extracellular space of tissues. Transudates are thin and watery and contain few cells or proteins.