Nomenclature of Neoplasms
Comparisons between Benign and Malignant Neoplasms
- Pattern of Growth
- benign: usually expansive with encapsulation, fibrous capsule
- malignant: infiltrative and expansive without encapsulation, both lmph and blood vascular involvement
- Rate of Growth
- benign: usually slow growing, mitotic figures are rare and normal in appearance
- malignant: slow or rapid growth, mitoses often numerous and abnormal
- Differentiation
- benign: usually uniform, resembles tissue of origin and is "well-differentiated"
- malignant: anaplasia = poorly differentiated (but note that malignant tumors range from well-differentiated to undifferentiated)
- Pleomorphism: increased N/C ratio, large nucleoli, atypical mitosis
- Recurrence after Removal
- benign: unusual if adequately excised
- malignant: frequent
- Metastasis
- benign: not observed
- malignant: often encountered
Nomenclature of Neoplasms – based on tissue of origin, and whether the tumor is benign or malignant.
- Benign (-oma)
- Adenoma
- Benign epithelial neoplasm that forms a glandular pattern.
- A neoplasm derived from glands but does not necessarily form glandular patterns.
- example: thyroid follicular adenoma, cystadenoma of ovary, adrenocortical adenoma
- Papilloma – Benign epithelial neoplasm producing macroscopically or microscopically visible fingerlike or warty projects from epithelial surfaces.
- Teratoma – Neoplasms made up of cellular elements representing more than or (usually all three) of the embryonic germ layers.
- example: Ovarian teratoma – the ovary had ectodermal growth in it… i.e. HAIR!
- Hamartoma – A disorganized mass of mature, specialized tissues or cells indigenous to a particular site.
- example: Lung hamartoma – mixture of mature respiratory and cartilage cells in the lung.
- Choristoma – Nests of "normal" tissues in ectopic locations.
- example: a piece of lung growing in your leg. Another controversial example is "head up your ass".
- Benign or Malignant
- Polyp – Benign or malignant neoplasm that produces a macroscopically visible projection above a mucsal surface.
- example: colonic polyp (nomeoplastic/hyperplastic or neoplastic/adenoma), polypoid cancers.
- Malignant
- Carcinoma – malignant epithelial neoplasm (two types)
- example: Adenocarcinoma, squamous cell carcinoma, or can specify site (renal cell adenocarcinoma), or can specify differentiation (large cell undifferentiated carcinoma of lung).
- Sarcoma – Malignant mesenchymal neoplasm (mesenchymal means anything that is not epithelial)
- example: liposarcoma, osteosarcoma, chondrosarcoma
- Benign and Malignant
- Tumors with "Mixed" Differentiation – adenofibronoma/fibroadenoma, carcinosarcoma/malignant mixed tumor.
- Inappropriate Nomenclature – You’d think they are benign but they are malignant
- Hepatoma – hepatocelluar carcinoma
- Melanoma – melanocarcinoma
- Lymphoma
- Astrocytoma/glioma
- Seminoma