Ewing’s Sarcoma/Primitive Neuroectodermal Tumor of the Uterine Corpus

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Ewing's sarcoma (ES)/primitive neuroectodermal tumor (PN-ET) is defined as a round cell sarcoma that shows varying degrees of neuroectodermal differentiation. The term PNET was first introduced by Hart and Earle in 1973. 1 Cases of ES/PNET in the female genital tract are rare. Now we report a case of ES/ PNET arising in the uterine body which was confirmed by all studies performed, including morphologic, immunohistochem-ical, ultrastructural, and cytogenetic examinations. A 23-year-old Korean woman presented with irregular vagi-nal bleeding and low abdominal pain. Ultrasonography and magnetic resonance imaging of the pelvis revealed a huge intramu-ral mass of the uterus, measuring 8.4 cm in diameter. Bilateral adnexal abnormality or significant lymphadenopathy was not identified. Total abdominal hysterectomy, bilateral salpingo-oo-phorectomy, and lymph node dissections were done. Grossly, the uterus was slightly enlarged, measuring 6×13×8 cm. On opening the uterus, there was a mass arising from the anterior wall of the uterus, bulging out into the endometrial cavity with an area of ulceration on the endometrium. The cut surface of the uterus showed an unencapsulated but relatively well-circumscribed intramural tumor, measuring 9×7.5 cm (Fig. 1). The tumor showed a homogeneous gray-tan, solid, and fish-fleshy appearing cut surface with no conspicuous necrosis or hemorrhage. The tumor abutted the endometrium and sero-sal surface of the uterus. Both ovaries and salpinges were grossly unremarkable without any enlargement or tumor identified. Microscopically, the tumor was composed of relatively uniform small round-to-oval neoplastic cells arranged in a diffuse sheet or solid nesting pattern of growth with intervening fibrous septa throughout the myometrium. The tumor invaded the en-dometrium focally but did not involve the serosal surface of the uterus. There were numerous areas of lymphatic tumor invasion and a metastatic tumor implant on the surface of the left ovary, but there was no evidence of metastatic tumor in the pelvic lymph nodes. The tumor cells had scanty cytoplasm with indistinct cytoplasmic border, round-to-oval nuclei of stippled chromatin pattern, and inconspicuous nucleoli (Fig. 2). Mitoses, apoptotic bodies, and focal areas of necrosis were frequently found (22/10 high power fields of mean mitotic count). Pseudorosettes were also frequently present but no malignant glandular areas were identified within or adjacent to the tumor. On immunohistochemical …