Oncopathology – key definition: In cancers and malignant neoplasms, what is the term for the reversion of cells to a more primitive, less differentiated state accompanied by loss of normal architecture and function?

Introduction:
A cornerstone concept in pathology is how malignant cells diverge from normal cells. One hallmark of aggressive malignancy is the loss of differentiation. This question checks your ability to recall the precise term for that loss of mature features in cancer cells.

Given Data / Assumptions:

• We are dealing with vocabulary used in surgical pathology and oncology.
• The focus is the regression to a primitive, undifferentiated phenotype.
• No calculation is needed; careful term recognition is required.

Concept / Approach:
Anaplasia literally means “to form backward.” In tumors, anaplasia describes a loss of structural and functional differentiation of normal cells. It is reflected by pleomorphism, hyperchromasia, high nuclear-to-cytoplasmic ratio, prominent nucleoli, abnormal mitoses, tumor giant cells, and architectural chaos. Greater anaplasia usually correlates with higher grade and more aggressive behavior.

Step-by-Step Solution:
Identify what is being asked: loss of differentiation toward an immature phenotype. Map the definition to the standard term used in pathology. Recognize “anaplasia” as the specific word describing dedifferentiation in malignant neoplasms. Select the option that exactly matches this concept.

Verification / Alternative check:
Textbook grading schemes for carcinomas and sarcomas commonly list anaplasia as a criterion of poor differentiation. Histologic images with marked pleomorphism and bizarre mitotic figures exemplify anaplastic change.

Why Other Options Are Wrong:
Neoplasia – general new, uncontrolled growth; does not specify differentiation loss.

Metastasis – spread to distant sites; not about cellular maturity.

Oncogenic – refers to the capacity to cause tumors; not a morphologic descriptor.

Dysplasia – disordered growth in epithelia, potentially premalignant but not necessarily fully undifferentiated.

Common Pitfalls:
Confusing dysplasia with anaplasia; dysplasia can be reversible and graded, whereas anaplasia denotes frank malignant dedifferentiation.

Final Answer:
Anaplasia.