Which two histological characteristics are indicative of fibrosarcoma?

The histological characteristics indicative of fibrosarcoma primarily include pleomorphism and high mitotic activity. Fibrosarcomas are malignant tumors of mesenchymal origin that exhibit variability in cell shape and size (pleomorphism), which reflects the aggressive nature of the tumor. This variability is a hallmark of malignancy, demonstrating that the tumor cells are undergoing uncontrolled growth and displaying abnormal characteristics.

In addition, high mitotic activity is another key feature of fibrosarcoma. This indicates that the tumor cells are proliferating rapidly, which can contribute to the aggressive clinical behavior associated with these tumors. Such marked mitotic activity, often seen in malignancies, suggests that a significant number of cells are dividing at any given time, further emphasizing the tumor's invasive potential.

The other characteristics listed, such as uniformity in cell size and low mitotic activity, typically correspond to benign lesions or well-differentiated tumors, which do not exhibit the aggressive behavior seen in fibrosarcomas. Similarly, low cellularity and fibrous stroma are characteristics more associated with reactive processes or low-grade tumors rather than a highly malignant process like fibrosarcoma. Thus, the combination of pleomorphism and high mitotic activity distinctly identifies fibros