FNA Quiz 22 The parents of a 6 year-old boy sought medical attention after he developed a swelling in the left side of   his face over a period of five weeks. Physical examination revealed a 5 cm protuberant non-tender mass in the left cheek and a fine needle aspiration biopsy was performed. Based on the cytologic features of the tumor illustrated below (Panel A to C), the cell block slide provided (Panel D) MOST LIKELY represents an immunohistochemical stain for:

A CD99.

B Desmin.

C S-100 protein.

D Synaptophysin

E Pan-cytokeratin (AE1/AE3).