fig5
![The WHO 2021 thymoma classification: a work in progress](https://image.oaes.cc/ff80e65d-a3b6-4b2a-b5b8-57ecb8907b8a/4616.fig.5.jpg)
Figure 5. Type B1 thymoma: (A) scanning magnification shows the appearance of a “blue cell tumor” due to the massive amounts of small lymphocytes, and the characteristic lobulation separated by broad fibrous bands (2×); (B) area of “medullary” differentiation is seen in a B1 thymoma, characterized by a rounded zone that looks paler than the surrounding tissue owing to a decrease in the number of small lymphocytes (20×).