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)