(B) Complete loss of Differentiation[?]When a tumor cell loses its differentiation it gradually gains features of Dysplasia.oDysplacia is a process of gradual loss of differentiation.oIt is an abnormal growth which may precede malignancy.oComplete loss of differentiation = Anaplasia[?]Anaplasia:oIt implies dedifferentiation or loss of structural & functional differentiation of normal cells.oEg., Malignant tumours formed of undifferentiated cells are called anaplastic tumours, anaplasia is a marker of cancer.[?]Differentiation & Anaplasia:oDifferentiation refers to the extent to which the tumour cells resemble their normal counterpart, both morphologically & functionally.oWell-differentiated tumours, whether benign or malignant, tend to retain the functional characteristics of their counterparts such as the product on of hormones in tumours of endocrine origin or keratin in squamous epithelial tumours. Anaplastic tumours have no specialized functional activity.[?]Differentiation & Anaplasia:oDysplasia = disorderly (dys-) growth (-plasia)o'Dysplasia' is used to describe disorderly changes in non-neoplastic epithelial cells.oGraded as mild, moderate or severe.-Mild-moderate: Usually reversible-Severe: Usually progresses to carcinoma in situ (CIS).oNext step after CIS: Invasive carcinomaoAnaplasia = a state of complete un-differentiationoLiterally, 'toform (-paisa) backwards (ana-)'oMisnormer! Cells don't de-differentiate.oJust means cells are very poorly-differentiated.oAlmost always indicates malignancy.[?]Differentiation is defined as the extent of morphological and functional resemblance of parenchyma tumour cells to corresponding normal cells.oIf the deviation of neoplastic cell in structure and function is minimal as compared to normal cell, the to is known as "well differentiated" e.g. Benign tumour.oPoorly differentiated or undifferentiated or de-differ is poor structural and functional resemblance to corresponding normal cell.oAnaplasia is defined as lack of differentiation and is a characteristic feature of most malignant tunoRefers to a lack of differentiation in neoplastic cells.oWell-differentiated tumors resemble their tissue of originoPoorly-differentiated or undifferentiated (anaplastic) tumor cells appear primitive and lack specialization along any particular cell line.