fig8

Figure 8. Type B3 thymoma: (A) higher magnification of type B-3 thymoma shows the pavement-like architecture resembling immature squamous epithelium due to the sharply apposed cell membranes (40×); (B) cytologic features of B3 thymoma include enlargement of nuclei, increase in chromatin pattern, and occasional prominent nucleoli and larger, more atypical cells (60×). Low mitotic activity is generally present in these tumors, averaging 1-2 per 10 high power fields.