38. Neoplasia, nomenclature, definitions. Terminology (nomenclature) of neoplasms
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, however all tumors are neoplasms.
Cancer is the term we use for a malignant (evil) tumor. Strictly 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.
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
Tumours 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 |
Tumours 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 |
Tumours of nervous system cells
| Tissue of origin | Benign variation | Malignant variation |
|---|---|---|
| Melanocytes | Nevus | Malignant melanoma |
Tumours 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 |
Tumours 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.