An Unusual Hybrid Salivary Gland Tumor: Molecular Analysis Informs the Potential Pathogenesis of This Rare Neoplasm

Figure 2

Immunohistochemical findings of the parotid gland mass. (a) A CK5/6 stain highlights the peripheral abluminal squamoid cells in mucoepidermoid carcinoma (upper left) as well as a prominent abluminal myoepithelial cell population in the basal cell adenoma (lower middle). (b) Similarly, p63 shows peripheral positivity in both tumor components. (c) A stain for CK7 highlights mucocytes and cells adjacent to glandular lumens in the mucoepidermoid carcinoma and patchy cells throughout the basal cell adenoma with a subset of luminal cells staining intensely. (d) The proliferation index as estimated by an immunohistochemical stain for Ki-67 is approximately 3-4% in the mucoepidermoid carcinoma; the basal cell adenoma is no longer present in the deeper level used for immunohistochemistry.

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