38. Neoplasia, nomenclature, definitions. Terminology (nomenclature) of neoplasms

Page created on November 22, 2018. Last updated on November 24, 2022 at 06:30

Definitions

When talking about cancer, it’s important to have our nomenclature in order.

A neoplasm is any abnormal mass of tissue that grows “outside” and uncoordinatedly with that of the normal tissue. The word literally means “new growth” in Greek. All cancers are neoplasms. Neoplasms don’t increase in size due to their local environment; they’re autonomic. They don’t care.

The word tumor was originally used for any swelling, however nowadays it’s used to indicate any neoplastic mass. Tumors can be benign, precancerous or malignant. Not all neoplasms are tumors (as some neoplasms like leukaemia don’t organise into masses), however all tumors are neoplasms (this is debateable, some consider hamartomas not to be neoplasms, for example).

Cancer is the term we use for a malignant (evil) tumor. Not all cancers are tumors; leukaemia for example is a cancer but not a tumor. The word malignant indicates that the tumor can invade and destroy adjacent structures. Oncology is the study of neoplasms, especially cancers.

When we talk about the dignity of a tumor, we talk about how it behaves, or, in more precise terms, whether it’s benign or malignant. The following table illustrates the differences:

Benign	Malignant
Most commonly innocent	Destroy adjacent structures
Remain localized	Invade adjacent structures
Does not spread (are never metastatic)	Can spread to distant sites (can metastasize)
Easily removable with surgery	Not easily removable with surgery

With modern medicine can even malignant tumors be treated or cured, especially if they’re caught in the early stages. Screening is therefore important.

Neoplasm terminology

Tumors have different names depending on whether they’re benign or malignant, and depending on which cell type they originate from. They’re best summed up in tables:

Tumors comprised of only one parenchymal cell type

Tumors of mesenchymal origin

Connective tissue and derivatives:

Tissue of origin	Benign variation	Malignant variation
Fibrous connective tissue	Fibroma	Fibrosarcoma
Adipose tissue	Lipoma	Liposarcoma
Cartilage	Chondroma	Chondrosarcoma
Bone	Osteoma	Osteogenic sarcoma

Endothelial and related tissues:

Tissue of origin	Benign variation	Malignant variation
Blood vessels	Haemangioma	Angiosarcoma
Lymph vessels	Lymphangioma	Lymphangiosarcoma
Synovium	— none —	Synovial sarcoma
Mesothelium	— none —	Mesothelioma
Brain coverings	Meningioma	Invasive meningioma

Blood cells and related cells:

Tissue of origin	Benign variation	Malignant variation
Haematopoietic cells	— none —	Leukaemias
Lymphoid tissue	— none —	Lymphomas

Muscle cells:

Tissue of origin	Benign variation	Malignant variation
Smooth muscle	Leiomyoma	Leiomyosarcoma
Striated muscle	Rhabdomyoma	Rhabdomyosarcoma

Tumors of epithelial origin

Tissue of origin	Benign variation	Malignant variation
Stratified squamous	Squamous cell papilloma	Squamous cell carcinoma
Basal cells of skin	— none —	Basal cell carcinoma
Epithelial lining of glands or ducts	Adenoma	Adenocarcinoma
	Papilloma	Papillary carcinoma
	Cystadenoma	Cystadenocarcinoma
Respiratory passages	Bronchial adenoma	Bronchogenic carcinoma
Renal epithelium	Renal tubular adenoma	Renal cell carcinoma
Liver cells	Liver cell adenoma	Hepatocellular carcinoma
Transitional epithelium (urinary tract)	Transitional cell papilloma	Transitional cell carcinoma
Placental epithelium	Hydatidiform mole	Choriocarcinoma
Testicular epithelium (germ cells)	— none —	Seminoma, embryonal carcinoma

Tumors of nervous system cells

Tissue of origin	Benign variation	Malignant variation
Melanocytes	Nevus	Malignant melanoma

Tumors originating from more than one cell type, but from the same germ layer

Tissue of origin	Benign variation	Malignant variation
Salivary glands	Pleomorphic adenoma	Malignant mixed tumor of salivary gland origin
Kidney precursors	— none —	Wilms tumor

Tumors originating from more than one cell type, and from different germ layers

Tissue of origin	Benign variation	Malignant variation
Totipotent cells in gonads or in embryonic rests	Mature teratoma	Immature teratoma
	Dermoid cyst	Teratocarcinoma

You can see from this that malignant mesenchymal tumors have the -sarcoma ending and malignant epithelial tumors have -carcinoma ending. Benign mesenchymal tumors have a simple -oma ending, while for benign epithelial tumors the naming is more complex but usually involves the -adenoma ending.