Malignant neoplasms arising from tissue embryologically derived from
ectoderm or endoderm are usually carcinomas. Examples include:
Squamous cell carcinoma of cervix
Adenocarcinoma of stomach
Renal cell carcinoma
Malignancies arising from mesoderm (connective tissues) are usually sarcomas. Examples include:
Neoplasms with more than one cell type but arising from only one germ
layer are called "mixed tumors". The best example is the benign mixed tumor (also called pleomorphic adenoma) of salivary gland.
Neoplasms with more than one cell type and arising from more than one germ layer are called teratomas. Such neoplasms are common in the ovary.
Neoplasms ending in "-blastoma" resemble primitive embryonic tissues, which are often pediatric neoplasms. Examples include:
Not all malignant neoplasms have benign counterparts:
Hematopoietic and lymphoid cells (as in bone marrow and lymph node) give
rise to leukemias and lymphomas. They have no benign counterpart.
Gliomas (astrocytomas, oligodengrogliomas, glioblastoma multiforme, etc)
arise from glial cells in the CNS. They have no benign counterpart.
Arise from epithelial surfaces (in gastrointestinal tract, in respiratory tract, in urogenital tract, in biliary tract, in skin) and in organs with epithelial-lined ducts (breast, pancreas, salivary gland, liver). Endocrine
glands, including testis and ovary, may also give rise to carcinomas. In
general, carcinomas are composed of polygonal-shaped cells.
Carcinomas that form glandular configurations are called adenocarcinomas.
Carcinomas that form solid nests of cells with distinct borders,
intercellular bridges, and pink keratinized cytoplasm are called squamous cell
Arise from soft tissues (connective tissues such as cartilage, bone, or fascia, smooth or skeletal muscle, blood vessels, lymph vessels, coverings of
organs such as mesothelium). In general, sarcomas are composed of very
pleomorphic spindle-shaped cells. Sarcomas are generally big and bad.