Objective: To investigate the clinicopathological characteristics, pathological diagnosis of Ewing's sarcoma of the central nervous system. Methods: Six cases of Ewing's sarcoma of the central nervous system diagnosed at the First Affiliated Hospital of Nanjing Medical University, Nanjing, China from 2015 to 2022 were collected. The clinical manifestations, histological morphology, immunophenotype and molecular genetics of these cases were analyzed. The related literature was reviewed. Results: There were four males and two females, with a male to female ratio of 2∶1. The onset age was 17-40 years, with a median age of 23 years. All 6 tumors were located in the spinal cord (2 cases of cervical vertebra, 1 case of thoracic vertebra, 2 cases of lumbar vertebra, and 1 case of sacral vertebra). The patients' clinical manifestations were mostly lumbago, weakness and numbness of lower limbs/limbs. In 1 case, the tumor recurred and metastasized to the suprasellar region and the third ventricle. Microscopically, the tumor showed diffuse infiltrative growth. In some cases, the tumor was closely related to the spinal meninges. The tumor cells were arranged in sheet, lobular, thin-rope, and nest-like patterns. Homer-Wright rosette was visible. The tumor cells were small to medium in size, and most of them had scant cytoplasm. A few cells had clear cytoplasm. Some areas were rhabdoid. The tumor cell nuclei showed focal mild pleomorphism. The chromatin was uniform and delicate while the nucleoli were not obvious. Mitosis was commonly seen. The tumor was separated by fibrous connective tissue and may be accompanied by mucinous degeneration. Immunohistochemistry showed that all tumors were positive for CD99, NKX2.2, Fli1, ERG. ATRX, H3K27me3, INI1 and BRG1 were all retained. Immunohistochemical stains for EMA, GFAP and Olig2 were negative. The Ki-67 proliferation index was 30%-70%. EWSR1 break-apart FISH test was positive. Conclusions: Ewing's sarcoma is rare in the central nervous system and needs to be distinguished from a variety of neoplasms with primitive undifferentiated small cell morphology. Immunohistochemistry and molecular genetics may be required for a proper diagnosis.
Humans ; Male ; Female ; Young Adult ; Adult ; Adolescent ; Sarcoma, Ewing/pathology* ; Proto-Oncogene Protein c-fli-1 ; Immunohistochemistry ; Biomarkers, Tumor/genetics* ; Central Nervous System/pathology*

Base Sequence ; Formaldehyde ; chemistry ; Humans ; Molecular Sequence Data ; Oncogene Proteins, Fusion ; genetics ; Paraffin Embedding ; Proto-Oncogene Protein c-fli-1 ; genetics ; RNA, Neoplasm ; genetics ; metabolism ; RNA-Binding Protein EWS ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Rhabdomyosarcoma ; genetics ; Sarcoma, Ewing ; genetics ; Sarcoma, Synovial ; genetics ; Soft Tissue Neoplasms ; genetics ; Tissue Fixation

BACKGROUNDEwing's sarcoma/peripheral primitive neuroectodermal tumor (ES/pPNET) is often difficult to distinguish from other small round cell tumors. The EWS-Ets gene fusions that result from chromosomal translocations in this tumor provide potential molecular diagnostic markers. To apply these molecular markers to commonly available archival materials, we evaluated the feasibility of detecting EWS-Ets including EWS-Fli1 and EWS-ERG fusion transcripts in paraffin-embedded tissues and its diagnostic value for detecting ES/pPNET.

METHODSThirteen paraffin-embedded samples of ES/pPNETs were retrieved from archives. Thirteen cases of other tumors with small round cell features (including rhabdomyosarcoma, neuroblastoma, lymphoma, small cell carcinoma, and desmoplastic small round cell tumor) were used as negative controls. Beta-actin and beta2-microglobulin were used as internal controls. A nested reverse transcriptase-polymerase chain reaction (RT-PCR)-based assay was performed to detect the EWS-Fli1 and EWS-ERG fusion transcripts.

RESULTSBeta-actin and beta2-microglobulin were detected in 10/13 and 13/13 ES/pPNETs, respectively. EWS-Fli1 fusion transcripts were detected in 11 of 13 (85%) ES/pPNETs. Three chimeric transcripts, all EWS-Fli1, were detected in ES/pPNET samples. Among 11 EWS-Fli1-positive cases, 7 cases had a type I fusion transcript involving fusion of EWS exon 7 with Fli1 exon 6, 2 cases had a type II fusion transcript involving EWS exon 7 with Fli1 exon 5, and 2 cases expressed fusion transcripts involving EWS exon 7 and Fli1 exon 8. Type I EWS-Fli1 fusion predominated over other types. Fusion types could not be distinguished in the remaining 2 cases. Thirteen negative controls did not show detectable chimeric messages. There was a significant relationship between EWS-Fli1 fusion transcripts and CD99 expression.

CONCLUSIONSMolecular detection of EWS-Fli1 fusion transcripts in formalin-fixed paraffin-embedded material by nested RT-PCR is feasible and is useful for the diagnosis and differential diagnosis of ES/pPNETs.

Adolescent ; Adult ; Child ; Female ; Humans ; Male ; Middle Aged ; Neuroectodermal Tumors, Primitive, Peripheral ; genetics ; pathology ; Oncogene Proteins, Fusion ; genetics ; Polymerase Chain Reaction ; Proto-Oncogene Protein c-fli-1 ; RNA, Messenger ; analysis ; RNA-Binding Protein EWS ; Sarcoma, Ewing ; genetics ; pathology ; Transcription Factors ; genetics

Extraskeletal Ewing's sarcoma (EES) is a rare soft tissue tumor morphologically indistinguishable from the more common Ewing's sarcoma of bone. We report a case of EES arising in the hard palate of 34-yr-old male patient. Microscopically, the monotonous small round cells without neuronal differentiation showed membranous positive immunoreactivity for MIC2/CD99 and vimentin. Ultrastructurally, the tumor cells showed a few intracytoplasmic organelles without evidence of neurosecretory granules or neurofilaments. The EWS-FLI1 chimeric gene was identified using the nested reverse transcriptase-polymerase chain reaction.
Adult ; Antigens, CD/analysis ; Cell Adhesion Molecules/analysis ; Humans ; Immunohistochemistry ; Male ; Oncogene Proteins, Fusion/genetics ; Palatal Neoplasms/genetics/metabolism/*pathology ; Palate, Hard/metabolism/*pathology ; Proto-Oncogene Protein c-fli-1/genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Sarcoma, Ewing's/genetics/metabolism/*pathology ; Transcription, Genetic ; Vimentin/analysis

OBJECTIVETo study the clinicopathologic features of primitive neuroectodermal tumor (PNET) in female genital tract.

METHODSSix cases of PNET arising in female genital tract were retrospectively reviewed. The clinicopathologic features, immunohistochemical findings and EWS gene translocation study results were analyzed.

RESULTSThe age of patients ranged from 10 to 27 years (mean = 20 years). The sites of involvement included ovary (1 case), uterus (1 case), vulva (2 cases) and vagina (2 cases). The greatest diameter of the tumor ranged from 2 to 10 cm (mean = 5.4 cm). The tumor had nodular appearance and showed grayish-pink fleshy cut surface, accompanied by foci of hemorrhage and necrosis. Histologically, the tumor was composed of malignant small round cells with indistinct cell borders, hyperchromatic nuclei, dense chromatin, tiny nucleoli and scanty cytoplasm. The tumor cells were arranged in sheets or lobules. Homer-Wright rosettes were identified in 1 case. Immunohistochemical study showed that the tumor cells were positive for CD99, FLI-1 and CD56 (6/6). Focal expression of vimentin (5/6), NSE (5/6), nestin (4/6), synaptophysin (4/6), S-100 protein (2/6) and chromogranin A (1/6) was also demonstrated. EWS gene translocation was detected in 5 cases studied. Follow-up information was available in 2 patients (7 and 17 months of follow up, respectively). One of them died of tumor metastasis 17 months after diagnosis. The other patient was still alive.

CONCLUSIONSPNET arising in female genital tract is rare. It mainly involves ovary, uterus, vulva and vagina. Immunohistochemical study using a panel of antibodies and fluorescence in-situ hybridization play an important role in definitive diagnosis of this rare malignancy.

12E7 Antigen ; Adolescent ; Adult ; Antigens, CD ; metabolism ; CD56 Antigen ; metabolism ; Cell Adhesion Molecules ; metabolism ; Child ; Female ; Follow-Up Studies ; Genital Neoplasms, Female ; genetics ; metabolism ; pathology ; surgery ; Humans ; Neuroectodermal Tumors, Primitive, Peripheral ; genetics ; metabolism ; pathology ; surgery ; Ovarian Neoplasms ; genetics ; metabolism ; pathology ; surgery ; Proto-Oncogene Protein c-fli-1 ; metabolism ; RNA-Binding Protein EWS ; genetics ; Retrospective Studies ; Translocation, Genetic ; Uterine Neoplasms ; genetics ; metabolism ; pathology ; surgery ; Vaginal Neoplasms ; genetics ; metabolism ; pathology ; surgery ; Vimentin ; metabolism ; Vulvar Neoplasms ; genetics ; metabolism ; pathology ; surgery ; Young Adult