Contributed by Min Han, MD, PhD and Rohit Bhargava, MD 
Contributed by Min Han, MD, PhD and Rohit Bhargava, MD
CLINICAL HISTORY
A postmenopausal woman in her 70s presented to the emergency room with abdominal pain. Physical examination revealed a non-mobile, non-tender right pelvic mass. Ultrasound found a large right ovarian mass, measuring about 9.2 x 7.6 x 7.2 cm. CA-125 was elevated at 42 (ref 0-20). Her past medical history was not contributory. The patient reported neither vaginal bleeding nor discharge. A total abdominal hysterectomy, bilateral salpingo-oophorectomy, lymphadenectomy and omentectomy were performed.
GROSS EXAMINATION
The right tubo-ovarian complex weighed 416.9 g, which consisted of an enlarged ovary and an unremarkable fallopian tube. The ovary was entirely replaced by a 10 x 9 x 8.5 cm, tan, solid mass with areas of hemorrhage. The outer surface was smooth. The left adnexa and uterus were unremarkable.
MICROSCOPIC EXAMINATION
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Microscopically, the tumor demonstrated admixed tubulocystic and papillary growth patterns with hyalinized stroma. Most tumor cells had abundant clear cytoplasm with enlarged nuclei, irregular nuclear membrane and conspicuous nucleoli. In areas with abundant stroma, the tumor grew in variably-sized cysts and glands lined by cuboidal to flat cells with moderate atypia. Mitotic count was 5/10 HPF. The tumor cells showed strong and diffuse nuclear positivity for HNF-1 beta and Pax-8 by immunohistochemistry. CK7+ was also positive. CK20 and ER were negative.
