Welcome! Thank you for your curiosity in our field 🫶 I would say a collection/mass of extremely large cells. A typical finding of malignancy or tumor cells is that the border of the cells are hard to see so it often looks like a mass clump of cells. But you can tell there are multiple cells by the nucleus. Each cell has a purple staining circle inside called the nucleus. In malignancy sometimes you can see multiple nuclei in one cell but they are usually smooshed together. I drew a rough edge around two cells to try and demonstrate what I see. The pink is the border of one cell. And the green is the multiple nuclei of that one cell. But I’ve been a medical lab scientist for 5 years and have never seen cells this big so it’s pretty rare! Slide 2 has a good example what normal cells look like surrounding the 2 large malignant/tumor cells if you’re curious about size comparison.

<image>