[1035] Primitive Neuroectodermal Tumors Primary in the Adnexal Region. The MD Anderson Experience.

Elizabeth Euscher, Gregory Fuller, Anais Malpica. MD Anderson Cancer Center, Houston, TX

Background: Primitive neuroectodermal tumors (PNET) of the adnexal region are rare.In this study, we present the clinicopathologic features of 18 such cases seen at our institution over a period of 20 years.
Design: 18 cases of PNETs were retrieved from our department files spanning 1990-present.All available pathology material was reviewed.Immunohistochemical studies (IHC) were performed in 15 cases, and Fluorescent In Situ Hybridization (FISH) for EWSR1 translocation in two cases.Clinical information was obtained from patients' (pts) charts.
Results: Ages ranged from 18-81 years (median 31).Clinical presentations included abdominal/pelvic pain, 6; pelvic mass, 5; abdominal distention, 1; incidental mass, 2;unknown, 4.Following surgical resection, 15 tumors were identified in the ovary, and 3 were para ovarian.FIGO stage was known in 15 cases: I (5); II (1); III (8); IV (1). 7 tumors were pure PNET; 11 were combined with mature teratoma (4), immature teratoma or yolk sac tumor (3), carcinoma (3), and carcinosarcoma (1).Histologically, all PNETs were characterized by small, round to spindle shaped cells predominantly in a patternless sheet.Other histologic features included: pseudopapillary structures (4), myxoid background (4), fibrillary background (7) and rosettes (true, 6; Homer-Wright, 7).In PNET combined with immature teratoma, recognition of the PNET was facilitated by an absence of primitive neurotubules and the presence of disorganized sheets of cells.The most commonly used IHC to facilitate diagnosis included: keratin, 2/13 pos;synaptophysin, 2/12 pos;neurofilament 9/9 pos;CD99 2/7 pos;GFAP 4/9 pos;CD56 6/7 pos;and S100 4/7 pos.FISH for EWSR1 demonstrated a translocation in 1 of 2 pts tested.Follow up ranging from 3-107 mos (median 18.5) was available for 16 pts:dead of disease, 9; alive with disease, 2; no evidence of disease, 5. 4 of 5 pts alive without disease were stage I at presentation with 1 currently completing adjuvant chemotherapy.All 5 pts received chemotherapy with 2 treated as neuroblastoma and 2 treated as Ewings sarcoma.
Conclusions: PNET of the adnexal region is aggressive and tends to affect young adult women.It is more commonly encountered in combination with other tumor types, particularly teratoma.Keratin, synaptophysin, and neurofilament are most useful in distinguishing PNET from other entities in the differential diagnosis.The low expression of CD99 suggests that adnexal PNETs more closely resemble central type PNET.
Category: Gynecologic & Obstetrics

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 127, Tuesday Afternoon


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