Is Mesothelioma a Type of Lung Cancer?

Key Differences Between Mesothelioma and Lung Cancer

Mesothelioma and lung cancer are distinct diseases that originate in different tissues. Lung cancer begins in the cells of the lung itself — the bronchi, bronchioles, or alveoli. Pleural mesothelioma originates in the pleura, the thin membrane that surrounds the lungs and lines the chest cavity. According to the American Cancer Society, this distinction is critical because the two cancers require different diagnostic approaches, treatments, and legal considerations.

The primary cause also differs. Mesothelioma is almost exclusively caused by asbestos exposure. Lung cancer is most commonly caused by smoking, although asbestos exposure also increases lung cancer risk — and the combination of asbestos exposure and smoking dramatically increases that risk. This causal distinction has significant legal implications for compensation claims.

Growth Patterns and Staging

The two cancers grow very differently. Lung cancer typically forms a discrete mass or tumor within the lung tissue that can often be seen on imaging as a distinct nodule. Mesothelioma, by contrast, grows as a diffuse layer of small nodules that spread across the pleural surface, eventually encasing the lung. This diffuse growth pattern makes mesothelioma more difficult to remove surgically.

Staging systems also differ. Lung cancer uses the standard TNM system that applies to most solid tumors. Mesothelioma has its own staging system adapted for its unique growth pattern, evaluating how far the cancer has spread across the pleural surfaces and whether it has invaded adjacent structures.

Diagnostic Differences

Accurate diagnosis is essential because treatment pathways diverge significantly. Pathologists use immunohistochemistry — special staining techniques on biopsy tissue — to distinguish mesothelioma from lung cancer. Certain protein markers, such as calretinin and WT-1, are positive in mesothelioma and negative in lung cancer, while others like TTF-1 show the opposite pattern. Misdiagnosis can lead to inappropriate treatment.

If you have been diagnosed with either condition and have a history of asbestos exposure, confirm your diagnosis with a pathologist experienced in mesothelioma. Second opinions from specialized centers can change the diagnosis in a meaningful percentage of cases.

Why the Distinction Matters Legally

The distinction between mesothelioma and asbestos-related lung cancer is important for legal compensation. Both conditions can result from asbestos exposure and may entitle patients to compensation. However, mesothelioma is considered definitive evidence of asbestos exposure (since asbestos is virtually the only cause), while lung cancer related to asbestos may require additional evidence to establish the connection, particularly if the patient is a smoker.

An experienced attorney can evaluate your diagnosis and exposure history to determine the best legal strategy, regardless of whether you have mesothelioma or asbestos-related lung cancer. Contact us at 1-800-400-1805 for a free consultation.