Primary tumors are classified based on their histological appearance and tissue of origin. Common classifications include:
- Carcinomas: Tumors arising from epithelial cells, such as adenocarcinoma or squamous cell carcinoma. - Sarcomas: Tumors originating from connective tissues like bone, cartilage, or fat. - Lymphomas: Tumors derived from lymphatic tissues. - Gliomas: Tumors that arise from glial cells in the nervous system.
