Figure 5.

Immunohistochemical profile of OSCC with sarcomatoid component, Case 2. A, Membranous E-cadherin expression is preserved in the squamous component (1), but lost in the sarcomatoid component (2, arrow). Small images: high power views of the framed areas in the section overview. Corresponding FAK staining (arrow → right) shows accentuation of the invasion front in the squamous component (1), but strong cytoplasmic staining throughout the tumor in the sarcomatoid component (2). Size bars: 0.2 mm. B, P63 staining is strong in adjacent mucosa (1) and the squamous tumor component (2), but absent in the sarcomatoid component (3). A magnified area from region 3 shows nuclear SNAI1 positivity (arrow → right). A lymph node metastasis resected at initial presentation is completely negative for p63 (see overview and magnified insert; asterisk indicating the carcinoma). C, A temporal fossa metastasis 26 months after initial presentation is positive for E-cadherin and SNAI1, but negative for p63.