Sebaceous Carcinoma Arising in Mature Cystic Teratoma of Ovary
A 69-year-old gravida 4, para 4 Korean woman visited our hospital with a two week history of pelvic pain. Ultrasonography and computed tomography of the abdomen demonstrated a large pelvic mass measuring 22.0 cm in maximal diameter and with a small amount of ascites. Her preoperative serum cancer antigen 125 level was elevated at 430.5 U/mL. Together, these findings were suggestive of malignancy. A total abdominal hysterectomy with bilateral salpingo-oophorectomy and partial omentectomy were performed. A massive left ovarian mass and omental cake were noted in the pelvic cavity, and numerous nodules (1-2 cm in size) were scattered in the peritoneum and along the intestinal serosal surface. A neoplastic implant measuring 1.5 cm in diameter was also observed at the posterior portion of the uterine body. The right ovary was unremarkable. The resected left ovary measured 22.0 cm in diameter and weighed 2,180 g. The outer, capsular surface of the ruptured left ovary appeared ragged with scattered tumor implants measuring up to 1.2 cm in diameter. On the cut section, the left ovary was replaced by a unilocular cyst filled with keratin-like material and brownish-serous fluid. The luminal surface of the cyst was smooth, but a luminally-protruding and outer expanding mass measuring 6.0 cm in diameter was noted. The cut surface of the mass was relatively grayish-white in color and firm in the luminal portion and was tan-colored and friable with hemorrhagic necrosis in the outer, expanding portion (). Microscopically, the smooth cystic wall was lined by stratified squamous epithelium with underlying sebaceous glands and other skin adnexal structures, findings consistent with a typical mature cystic teratoma. Benign squamous epithelium was abruptly replaced by a nodular arrangement of germinative cells with a pushing border, which protruded into the cyst lumen (). The nodular portion showed an alternatively dark and white area, which corresponded to generative cells (dark) and sebaceous cells (light) with cytoplasmic lipid vacuoles. There was no cytologic atypia or sparse mitosis. Taken together, these findings led to a diagnosis of sebaceous adenoma. Beneath the nodular portion, infiltrating trabeculae or nests of atypical cells were noted. The infiltrating portion was mostly separated but was focally contiguous with the sebaceous adenoma (). Infiltrating cells exhibited conspicuous vacuoles in the cytoplasm and remarkable nuclear pleomorphism, prominent nucleoli, and frequent abnormal mitoses (). There was no peripheral nuclear palisading or cleft-like spaces between the lobules. Tumor cells were immunohistochemically positive for cytokeratin (CK) 7 (), CK19, high molecular weight CK, epithelial membrane antigen (EMA) (), carcinoembryonic antigen (CEA) (), and p63 (), but stains were negative for CK20, p53, vimentin, human placental alkaline phosphatase, α-inhibin, S100 protein, c-erbB-2, estrogen receptor, and progesterone receptor. Periodic acid-Schiff (PAS) was negative in the large, cytoplasmic inclusion. The uterine myometrium showed direct infiltration of the sebaceous carcinoma, and the omental mass also revealed the same histology. The patient developed sepsis two weeks after diagnosis and was discharged home with palliative care.