Table of Contents
Definition / general | Epidemiology | Sites | Clinical features | Diagnosis | Radiology description | Prognostic factors | Case reports | Treatment | Clinical images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosisCite this page: Gupta N. PNET / Ewing sarcoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/ovarytumorPNET.html. Accessed August 6th, 2020.
Definition / general
- Neuroectodermal tumors of ovary classified into 3 types: well, moderate and poorly differentiated
- PNET is poorly differentiated NET of ovary
- PNET is monophasic teratoma of ovary composed exclusively of neuroectodermal element
- Most common of all neuroectodermal ovarian tumors
- Morphologically resembles PNET of brain, also called 'central' PNET
- Aggressive tumors treated by chemotherapy and surgery
Epidemiology
- Young women 10 - 30 years
Sites
- Most common in kidney; also bone and soft tissue
Clinical features
- Abdominal / pelvic pain
Diagnosis
- Final diagnosis is confirmed by IHC
Radiology description
- USG: solid ovarian mass
Prognostic factors
- Survival rate varies from 10.8 months to 3 years (Korean J Obstet Gynecol 2012;55:777)
Case reports
- 18 year old woman with peripheral primitive neuroectodermal tumor of the ovary (Int J Gynecol Cancer 2004;14:370)
- 27 year old woman with central primary primitive neuroectodermal tumor (cPNET) arising from an ovarian mature cystic teratoma in pregnancy (Gynecol Oncol Case Rep 2013;4:56)
- 29 year old woman with peripheral primitive neuroectodermal tumor of the ovary confirmed by CD99 immunostaining (Am J Surg Pathol 1998;22:1417)
Treatment
- Surgery, radiation therapy, multiagent chemotherapy, or combination
- Chemotherapy is with vincristine, doxorubicin, cyclophosphamide and more recently ifosfamide and etoposide (Korean J Obstet Gynecol 2012;55:777)
Clinical images
Images hosted on other servers:
MRI and positron emission tomography (fig 2)
Gross description
- Large solid friable tumor with gray-white cut surface
Gross images
Images hosted on other servers:
Ovarian cyst
Microscopic (histologic) description
- Solid nests and sheets of monotonous, primitive and small round cells
- Numerous mitotic figures
- Rosettes with central lumen, neuroblastic rosettes, neuropil or foci of glial differentiation present
Microscopic (histologic) images
Images hosted on other servers:
Main tumor - teratoma, H&E
Nodular focus of PNET, H&E
Fibrous bands and rosettes - kidney, H&E
H&E, vimentin, synaptophysin, CD99 (fig 1)
CD99+, kidney
LCA-, NSE-
Strong immunoreactivity for CD99
Immunoreactivity for CD99, vimentin, and CK5 markers
Molecular / cytogenetics description
- t(11;22)(q24;q12), EWS-FLI1 chimeric RNA
- Overexpression of N-myc and EGFR
- Underexpression of Rb and ARHI
Differential diagnosis
- Other small cell tumors of ovary such as:
- Desmoplastic small round cell tumor: desmin positive
- Lymphoma: LCA positive
- Rhabdomyosarcoma: MyoD1 positive
- Small cell carcinoma of hypercalcemic type
- Small cell neuroendocrine carcinoma: synaptophysin / chromogranin positive
