Anaplasia(fromAncient Greekἀνά(ana)'backward' andπλάσις(plasis)'formation') is a condition ofcellswith poorcellular differentiation,losing themorphologicalcharacteristics of mature cells and their orientation with respect to each other and toendothelialcells. The term also refers to a group of morphological changes in a cell (nuclearpleomorphism,alterednuclear-cytoplasmic ratio,presence ofnucleoli,high proliferation index) that point to a possiblemalignant transformation.[1]
Such loss of structural differentiation is especially seen in most, but not all, malignantneoplasms.[2]Sometimes, the term also includes an increased capacity formultiplication.[3]Lack of differentiation is considered a hallmark of aggressive malignancies (for example, it differentiatesleiomyosarcomasfromleiomyomas). The termanaplasialiterally means "to form backward". It implies dedifferentiation, or loss of structural and functional differentiation of normal cells. It is now known, however, that at least some cancers arise fromstem cellsintissues;in these tumors failure of differentiation, rather than dedifferentiation of specialized cells, account for undifferentiatedtumors.
Anaplastic cells display markedpleomorphism(variability). Thenucleiare characteristically extremely hyperchromatic (darkly stained) and large. Thenuclear-cytoplasmic ratiomay approach 1:1 instead of the normal 1:4 or 1:6. Giant cells that are considerably larger than their neighbors may be formed and possess either one enormousnucleusor several nuclei (syncytia). Anaplastic nuclei are variable and bizarre in size and shape. Thechromatinis coarse and clumped, andnucleolimay be of astounding size. More important,mitosesare often numerous and distinctly atypical; anarchic multiple spindles may be seen and sometimes appear as tripolar or quadripolar forms. Also, anaplastic cells usually fail to develop recognizable patterns of orientation to one another (i.e., they lose normal polarity). They may grow in sheets, with total loss of communal structures, such asglandformation or stratifiedsquamousarchitecture. Anaplasia is the most extreme disturbance in cell growth encountered in the spectrum of cellular proliferations.[4]
See also
editReferences
edit- ^"Anaplasia"– via The Free Dictionary.
- ^"Anaplasia".Medical Definition from MediLexicon.Archived fromthe originalon 2014-03-06.Retrieved2014-03-06.
- ^"Anaplasia".Biology-Online Dictionary.Archived fromthe originalon 2019-12-08.Retrieved2008-12-12.
- ^Kumar V, Abbas AK, Fausto N, Mitchell R (2007).Robbins Basic Pathology(8th ed.). Philadelphia: Saunders Elsevier. pp. 176–177.ISBN978-1-4160-2973-1.