Apocrine adenocarcinoma arising in cystic teratoma of the ovary.

We present a rare case of an apocrine adenocarcinoma arising in a mature cystic teratoma of the ovary. The patient, a 41-year-old woman, was admitted to the hospital with low back pain and hypermenorrhea. A unilocular cystic tumor, measuring 5.5 x 5.0 cm in diameter, was found in her right ovary, and was removed. The tumor contained a mural nodule, measuring 8 x 7 mm in diameter. Microscopically, the unilocular cystic tumor was a teratoma consisting of mature cutaneous tissue with numerous hairs. The mural nodule was composed mostly of cords of epithelial cells with an infiltrative fashion and anastomosing tubular structures, which were lined partly by cells with eosinophilic cytoplasm and decapitation secretion. The cytoplasm contained iron granules as well as granules that were stained with periodic acid-Schiff, with and without diastase digestion.