210813.fig.006a
(a)
210813.fig.006b
(b)
Figure 6: Spindle cell (sarcomatoid) squamous cell carcinoma. (a) The keratinocyte derivation of this lesion cannot be identified with certainty based solely on histology in this poorly differentiated tumor (100x). (b) Immunohistochemistry for p63 identifies the squamous origin of the tumor (100x).