Review Question - QID 108478

The patient in this case is most likely to have bronchogenic carcinoma, more specifically squamous cell carcinoma given his asbestos exposure (from ship building) and smoking history. A CT scan of squamous cell carcinoma would most likely show a lower lobe mass with cavitation.

In a patient with asbestos exposure and a 60 pack-year history presenting with 3 weeks of cough and progressive dyspnea, one should be suspicious for malignancy. The chest radiograph findings of parenchymal opacities and pleural plaques suggest exposure to asbestos, but do not yet demonstrate a visible malignancy. Although asbestosis is commonly associated with mesothelioma, bronchogenic carcinoma is a much more common malignancy, particularly in patients with asbestos exposure and concurrent tobacco use. These two factors have been shown to be synergistic in the development of lung cancer. Mesothelioma accounts for at most 2-3% of all lung cancers. Bronchogenic carcinoma usually presents as a cavitary mass especially in its squamous cell carcinoma form. Upper lobe masses have been shown to have a higher rate of malignancy, except when asbestosis is the underlying etiology, in which case lower lobe masses may be more common. In this patient, no mass was observed on chest radiograph; however, chest radiograph is a poor screening agent for lung malignancies in smokers due to low sensitivity. Low-dose CT scanning is recommended for 55-80 year-old patients with at least a 30-pack-year smoking history.

Incorrect Answers:
Answer 1: Mesothelioma often presents as a mass along pleural surfaces and exists primarily in patients exposed to asbestos. A chest radiograph with reticular parenchymal markings and pleural plaques suggests asbestos-related damage in the lungs. However, bronchogenic carcinoma is still the most common malignancy to develop in patients with a history of smoking and asbestos exposure, even with significant asbestos pathology.

Answer 2: Honeycombing is not indicative of any malignant process, but exists in patients with significant interstitial lung disease such as idiopathic pulmonary fibrosis.

Answer 3: Air bronchograms are found on chest radiograph, and are usually seen with pulmonary consolidation or pulmonary edema. They can be seen in malignancy as well, but are nonspecific.

Answer 4: A granulomatous nodule is indicative of an inflammatory process such as histoplasmosis which can often mimic clinical symptoms of lung cancer and should be considered in a patient with recent travel to an endemic region. However, neither the CT findings nor histoplasmosis are consistently associated with any malignancy.

Bullet Summary:
Bronchogenic carcinoma is the most common lung cancer in patients with a smoking history and asbestosis. Although asbestos exposure is common in patients with mesothelioma, only 2-3% of all lung cancers in asbestos-exposed patients are mesothelioma.