Differentials
Benign reactive mesothelial hyperplasia
SIGNS / SYMPTOMS
Can be caused by several different processes; therefore, a history of infection, pulmonary infarcts, drug reactions, collagen vascular diseases, trauma, or surgery may be present.[49]
INVESTIGATIONS
Pleural biopsy is necessary to distinguish benign mesothelial hyperplasia from malignant pleural mesothelioma; invasion of underlying tissues favours mesothelioma.[49]
Benign asbestos-related pleural reactions
SIGNS / SYMPTOMS
Exposure to asbestos can cause several benign pleural reactions, including pleural effusion, pleural plaques, diffuse pleural fibrosis, and rounded atelectasis.[10] Differentiating these processes from malignant pleural mesothelioma can be difficult.
INVESTIGATIONS
Pleural plaques are frequently documented on plain chest x-ray, but CT is more sensitive for their detection. Slow progression of plaques is typical. The presence of plaques is associated with a greater risk of mesothelioma, but this is thought to be related to greater exposure or retained body burden, not malignant degeneration.[50]
Findings on chest CT scan (serial studies usually necessary) suggesting a malignant process include circumferential or nodular pleural thickening, involvement of the mediastinal pleura, or enlarged regional lymph nodes.[39]
Non-small cell lung cancer
SIGNS / SYMPTOMS
Typical features include cough, haemoptysis, chest pain, dyspnoea, and hoarseness (if recurrent laryngeal nerve paralysis).
Patients frequently look unwell and are short of breath, with signs of recent weight loss. Finger clubbing and hypertrophic osteoarthropathy may be present.
A significant history of smoking or asbestos exposure suggests that a primary lung neoplasm be strongly considered.
INVESTIGATIONS
Chest CT scan shows size, location, and extent of primary tumour, which is more often within lung parenchyma rather than pleural; evaluates for hilar and/or mediastinal lymphadenopathy and distant metastases.
Depending on the location of the tumour, bronchoscopic- or CT-guided biopsy provides pathological confirmation of diagnosis.
Small cell lung cancer
SIGNS / SYMPTOMS
Typical features include cough, haemoptysis, chest pain, dyspnoea, and hoarseness (if recurrent laryngeal nerve paralysis).
Patients frequently look unwell and are short of breath with signs of recent weight loss.
Finger clubbing and hypertrophic osteoarthropathy may be present.
A significant history of smoking or asbestos exposure suggests that a primary lung neoplasm be strongly considered.
Usually, wheezing from underlying chronic obstructive pulmonary disease (COPD) or bronchial obstruction, rales due to post-obstructive pneumonia or atelectasis, or diminished breath sounds from bronchial obstruction are present unless early disease.
INVESTIGATIONS
Chest CT scan shows massive lymphadenopathy and direct mediastinal invasion.
Depending on the location of the tumour, bronchoscopic- or CT-guided biopsy provides pathological confirmation of diagnosis.
Metastatic cancer
SIGNS / SYMPTOMS
Symptoms will relate to the site of the primary tumour, and there may be general symptoms of pain, weight loss, malaise, cough, dyspnoea, clubbing, and focal wheezing.
Physical findings may or may not be present depending on nature and stage of tumour.
INVESTIGATIONS
Chest CT scan shows one or multiple nodules of variable sizes from diffuse micronodular shadows (miliary) to well-defined masses. Pleural tissue thickening is rare.
Flexible bronchoscopy and biopsy shows characteristic malignant cells.
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