Why is the TNM staging system not applicable for lymphoma?

The TNM staging system is primarily used for solid tumors, where it assesses the size of the primary Tumor (T), the extent of regional lymph Node involvement (N), and the presence of distant Metastasis (M). In the context of lymphoma, particularly non-Hodgkin lymphoma and Hodgkin lymphoma, the disease has characteristics that make this system less applicable.

Lymphomas are cancers of the lymphatic system, with a unique pattern of spread that often involves multiple lymph nodes and areas of the body simultaneously rather than through a singular, predictable pattern as seen in solid tumors. They may not conform to the localized spread and defined structures commonly associated with the TNM classification. This non-specific, multifocal nature of lymphoma can complicate staging using the TNM classification.

Moreover, lymphomas can be classified based on their histological type and the degree of involvement across different anatomical sites, which the TNM system does not effectively capture. Therefore, relying solely on TNM for lymphoma staging can be inadequate. Instead, the Ann Arbor staging system is often preferred for lymphomas, which emphasizes the number of areas involved and whether they are above or below the diaphragm rather than the same criteria applied to solid tumors.

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