Fig.

Histologic features of the ovarian mass. A, Ovary (low power). Ovarian stroma with thick-walled blood vessels and corpora albicantia (top). Nodules of thyroid-type tissue composed of variable-sized follicles filled with colloid and lined by low cuboidal to columnar follicular epithelial cells (bottom). B, Ovary (high power). There is a hypercellular focus within the thyroid tissue showing a follicular and trabecular pattern of growth and decreased colloid. Note that the follicular cells are larger and have crowded oval to irregular nuclei with pale chromatin. C, Ovary (high power). Cells with pale to vesicular nuclear chromatin, elongated nuclei, and longitudinal nuclear grooves. A nuclear pseudoinclusion is visible (arrow). The cells have moderate amounts of eosinophilic cytoplasm. D, Ovary (high power). Follicular growth of intermediate-sized low cuboidal cells with a moderate amount of dense eosinophilic cytoplasm. The nuclei show crowding and overlapping. Note the pale nuclear chromatin and scant dense colloid.