A 47-year-old woman has felt a 'lump' in her neck for the past 2 months. On physical examination there is a firm nodule in the right lobe of her thyroid. Following fine needle aspiration and cytologic diagnosis of a neoplasm, a thyroidectomy is performed. Grossly, there is a 3 cm mass in the right lower pole that on sectioning is cystic and has papillary excrescences. Which of the following microscopic pathologic findings is most typical for this lesion?