A 5-year-old girl begins developing secondary sexual characteristics, including pubic hair growth and breast development. Her concerned parents bring her to the pediatrician for evaluation. An abdominal ultrasound examination reveals an ovarian mass. The mass is resected and pathologic examination reveals it to be a granulosa cell tumor. Which of the following histologic findings is a characteristic of this type of ovarian tumor?

A young patient presenting with precocious pubey and an ovarian mass is likely to have a granulosa cell tumor. Call-Exner bodies, small follicles filled with eosinophilic secretion, are an impoant diagnostic feature. Signet-ring cells are seen in Krukenberg tumors (bilateral metastatic involvement of the ovaries by a signet-ring carcinoma arising in the stomach). Signet-ring cells in Krukenberg tumor Schiller-Duval bodies are seen in yolk sac tumor (endodermal sinus tumor). Hyperfunctional thyroid tissue is found in struma ovarii and the Brenner tumor resembles transitional cell epithelium.