Tumor Terminology

o Tumor: an abnormal mass of tissue, where cells divide more than they should, or do not die when they should

o Neoplasm: new and uncontrolled proliferation of cells, benign or malignant

o Benign: slow-growing tumor, well circumscribed, does not infiltrate beyond the basement membrane

o Dysplasia: change or alteration in a cell (atypical nuclei), can be low or high grade

o Malignant: cells infiltrate the basement membrane and into adjacent tissue, and the margins are poorly circumscribed

o Metastasis: malignant cells disseminate to distant organs, and new tumors form

o Carcinoma: malignant tumor that originates from epithelial cells

 Squamous cell carcinoma: from squamous epithelial cells

 Adenocarcinomas: from glandular epithelial cells

 Small cell carcinoma: from neuroendocrine cells

o Sarcomas: (rare) malignant tumors from mesenchymal tissue (e.g., blood vessels, cartilage, bone, muscle)

 Osteosarcoma: originates in bone

 Liposarcoma: originate in adipose

 Chondrosarcoma: originates in cartilage

 Leiomyosarcoma: originates in smooth muscle

 Rhabdomyosarcoma: originates in skeletal muscle

 Angiosarcoma: originates in blood vessels

o Hematopoietic neoplasms: abnormal proliferation of cells in the bone marrow, blood, lymph nodes, spleen, or liver

 Lymphoma: malignant tumor from lymphoid cells (B or T lymphocytes)

 Leukemia: abnormal early hematopoietic cells in the bone marrow

o Melanoma: from melanocytes (skin)

o Brain tumor: from neurons, glial, choroid plexus, or meninges

o Teratoma: from germ cells. Examples: dermoid cyst, may be found in the testes or ovaries, composed of ectoderm, endoderm, or mesoderm