Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (592 page)

   Hematology: CBC with differential can detect eosinophilia, which may suggest drug rash with eosinophilia and systemic symptoms (DRESS) syndrome.

Suggested Readings

Bhadra K, Suratt BT. Drug induced lung diseases: a state of the art review.
J Respir Dis.
2009;30:1.

Ozkan M, Dweik RA, Ahmad M. Drug induced lung disease.
Cleve Clin J Med.
2001;68:782–795.
www.pneumotox.com
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CHEMICAL PNEUMONITIS
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   Definition

Chemical pneumonitis is inflammation of the lungs or difficulty breathing following acute or chronic inhalation exposure to a foreign substance or chemical fumes. Aspiration pneumonitis (Mendelson syndrome) is a chemical injury caused by the inhalation of sterile gastric contents during general anesthesia due to abolition of the laryngeal reflexes.

   Who Should Be Suspected?

A number of clinical features should raise the possibility of chemical pneumonitis: Abrupt onset of symptoms with prominent dyspnea; cough, low-grade fever, cyanosis, and diffuse crackles on lung auscultation; severe hypoxemia; and infiltrates on chest x-ray involving dependent pulmonary segments.

   Laboratory Findings

   Pulmonary function tests (PFTs): Show decreased compliance, abnormal ventilation–perfusion, and reduced diffusing capacity. Chest x-ray: Changes are noted within 2 hours. Bronchoscopy shows erythema of bronchi indicating acid injury.

   Blood gas: Studies often show that the partial pressure of oxygen is reduced to 35–50 mm Hg accompanied by a normal or low partial pressure of CO
₂
with respiratory alkalosis. Lactate can be an early marker of septic shock.

   Other: Elevated WBC count and increased neutrophils may be present.

CARCINOMA OF THE LUNG

   Definition

The term
lung cancer
, or bronchogenic carcinoma, refers to malignancies that originate in the airways or pulmonary parenchyma. Lung cancer is the second most diagnosed cancer in men and women, but it is the number one cause of death from cancer. Eighty-seven percent of all lung cancers are smoking related. Exposure to second-hand smoke also increases the risk of developing lung cancer. Other substances including asbestos, radon, radiation exposure, TB, industrial substances, and pollutants also increase the risk. Family history/genetics also play a role in the development of cancer.

Approximately 95% of all lung cancers are classified as either small cell lung cancer (SCLC) or non–small cell lung cancer (NSCLC). This distinction is essential for staging, treatment, and prognosis. Other cell types comprise about 5% of malignancies arising in the lung. NSCLC accounts for 80% and SCLC accounts for 20% of all total lung cancers identified. There are different types of NSCLC, including:

   
Squamous cell carcinoma
: Most common type in men. Forms within the lining of bronchial tubes.

   
Adenocarcinoma
: Most common in women and nonsmokers. Found in the glands of the lungs that produce mucus.

   
Bronchoalveolar carcinoma
: Rare subset of adenocarcinoma forms near lungs air sacs.