Final answer:
Cells with a high nucleus-to-cytoplasm ratio on a cytology slide are indicative of malignancy due to the characteristics associated with uncontrolled growth and division typical of cancerous cells.
Step-by-step explanation:
A cytology slide showing cells with a high nucleus-to-cytoplasm ratio would likely indicate that the cells are malignant. Cells that are malignant often have larger nuclei relative to their cytoplasm when compared to normal cells. This is because cancerous cells are characterized by uncontrolled growth and division, leading to noticeable changes in cell morphology such as an increased nucleus-to-cytoplasm ratio, which is an indicator of active cell division or a high number of genetic materials due to multiple copies of DNA present in cancer cells.