Oncologic pathology terminology: The structural abnormality and loss of differentiation seen in malignant cells is termed what in histopathology?

Introduction / Context:
Cancer pathology uses precise terms to describe cellular changes. Recognizing the word that captures structural abnormality and loss of differentiation is critical for interpreting biopsy reports and exam questions.

Given Data / Assumptions:

• We focus on structural cellular abnormalities.
• Options include proliferation, dedifferentiation, and spread.

Concept / Approach:
Anaplasia refers to lack of differentiation and marked pleomorphism with abnormal nuclear morphology, atypical mitoses, and disordered architecture—classic features of malignant transformation. Hyperplasia is an increase in the number of normal cells; metastasis refers to spread of cancer to distant sites, not the structural abnormality itself.

Step-by-Step Solution:
Define anaplasia: loss of differentiation with structural atypia. Contrast with hyperplasia: increased cell numbers but preserved differentiation. Contrast with metastasis: a process of spread, not morphology. Select anaplasia as the term for structural abnormality.

Verification / Alternative check:
Histological criteria (nuclear-cytoplasmic ratio, pleomorphism, abnormal mitotic figures) align with anaplasia in standard pathology texts.

Why Other Options Are Wrong:

• Hyperplasia: quantitative increase, architecture relatively normal.
• Metastasis: dissemination pathway rather than cell structural abnormality.
• All of these: incorrect because only anaplasia matches the definition.

Common Pitfalls:
Equating malignancy with metastasis; malignancy can be present without metastasis, and the morphological term is anaplasia.

Final Answer:
anaplasia