How are tumors classified according to pathology?

Generally, tumors can be classified into several types based on pathological characteristics, mainly including epithelial tissue tumors, mesenchymal tissue tumors, lymphohematopoietic tissue tumors, neural tissue tumors, and germ cell tumors. A detailed analysis is as follows:

1. Epithelial Tissue Tumors: These originate from various types of epithelial tissues, such as the skin epidermis, gastrointestinal mucosa, and breast ductal epithelium. These tumors can be further divided into benign and malignant types. Benign examples include adenomas and papillomas, which grow slowly, have clear boundaries, and do not metastasize. Malignant types are known as carcinomas, such as squamous cell carcinoma and adenocarcinoma, which exhibit invasive growth, easily infiltrate beyond tissue boundaries, and tend to metastasize to other sites.

2. Mesenchymal Tissue Tumors: These arise from mesenchymal tissues such as fat, muscle, bone, blood vessels, and fibrous tissue. Common benign forms include lipomas and leiomyomas, which are soft or firm in texture and typically grow in an expansive manner. Malignant forms are called sarcomas, such as liposarcoma and osteosarcoma, which grow rapidly, invade surrounding tissues early in their course, and frequently spread via hematogenous (blood) metastasis.

3. Lymphohematopoietic Tissue Tumors: These originate from lymphocytes, hematopoietic stem cells, and related precursors, commonly occurring in hematopoietic and immune organs such as lymph nodes, bone marrow, and spleen. Common types include lymphomas and leukemia. These tumors often present with abnormal hematopoiesis or enlarged lymph nodes and require treatment approaches that differ from those used for other tumor types.

4. Neural Tissue Tumors: These derive from neural tissue, including neurons, glial cells, and Schwann cells, and can occur in both the central and peripheral nervous systems. Benign examples include schwannomas and meningiomas, most of which can be completely removed surgically. Malignant types, such as glioblastoma and neuroblastoma, grow rapidly, cause severe damage to surrounding neural tissues, and generally have a poor prognosis.

5. Germ Cell Tumors: These originate from germ cells and most commonly occur in reproductive organs such as the testes and ovaries, but may also appear in midline locations such as the mediastinum and sacrococcygeal region. Benign types include mature teratomas, which may contain various differentiated tissues such as hair, sebum, and bone. Malignant types, such as seminomas and yolk sac tumors, tend to metastasize via blood or lymphatic routes and are generally highly sensitive to radiotherapy and chemotherapy.

In clinical practice, accurate pathological classification of tumors is crucial for determining treatment strategies. Physicians select appropriate treatments—such as surgery, radiation therapy, chemotherapy, or targeted therapy—based on tumor type, stage, and other factors. Regular follow-up monitoring is also essential to evaluate treatment response and adjust therapeutic strategies accordingly.