Primitive Neuroectodermal Tumors of the Female Genital Tract: A Morphologic, Immunohistochemical, and Molecular Study of 19 Cases.

Primary primitive neuroectodermal tumor (PNET) of the female genital tract is rare, and its proper classification remains unclear. The clinical, histologic, and immunophenotypic features as well as EWSR1 rearrangement status of 19 gynecologic PNETs, including 10 ovarian, 8 uterine, and 1 vulvar tumors, are herein reported. Patient age ranged from 12 to 68 years, with a median age of 20 and 51 years among those with ovarian and uterine PNETs, respectively. Morphologic features of central nervous system (CNS) tumors were seen in 15 PNETs, including 9 medulloblastomas, 3 ependymomas, 2 medulloepitheliomas, and 1 glioblastoma, consistent with central PNET. The remaining 4 PNETs were composed entirely of undifferentiated small round blue cells and were classified as Ewing sarcoma/peripheral PNET. Eight PNETs were associated with another tumor type, including 5 ovarian mature cystic teratomas, 2 endometrial low-grade endometrioid carcinomas, and a uterine carcinosarcoma. By immunohistochemistry, 17 PNETs expressed at least 1 marker of neuronal differentiation, including synaptophysin, NSE, CD56, S100, and chromogranin in 10, 8, 14, 8, and 1 tumors, respectively. GFAP was positive in 4 PNETs, all of which were of central type. Membranous CD99 and nuclear Fli-1 staining was seen in 10 and 16 tumors, respectively, and concurrent expression of both markers was seen in both central and Ewing sarcoma/peripheral PNETs. All tumors expressed vimentin, whereas keratin cocktail (CAM5.2, AE1/AE3) staining was only focally present in 4 PNETs. Fluorescence in situ hybridization was successful in all cases and confirmed EWSR1 rearrangement in 2 of 4 tumors demonstrating morphologic features of Ewing sarcoma/peripheral PNET and concurrent CD99 and Fli-1 expression. In conclusion, central and Ewing sarcoma/peripheral PNETs may be encountered in the female genital tract with central PNETs being more common. Central PNETs show a spectrum of morphologic features that overlaps with CNS tumors but lack EWSR1 rearrangements. GFAP expression supports a morphologic impression of central PNET and is absent in Ewing sarcoma/peripheral PNET. Ewing sarcoma/peripheral PNETs lack morphologic features of CNS tumors.

Meningeal Ewing Sarcoma/Peripheral PNET: Clinicopathological, Immunohistochemical and FISH study of four cases.

Meningeal Ewing Sarcoma (ES)/peripheral primitive neuroectodermal tumor (pPNET) is a rare diagnostically challenging small round cell tumor in the CNS. This study investigates the clinical pathological features of four cases of this tumor from archives of 6 years in our hospital. Patients were within the median age of 21.5 years and male to female ratio was 1:1. The tumors distributed at the supra-tentorial location, posterior fossa and lumbar vertebral canal, usually presenting as the dura-sited nodule or having close connection with the meninges within the cranium or vertebral canal. Histopathologically, small round undifferentiated tumor cells with hypercellularities, scant cytoplasm and inconspicuous nucleoli were observed, although some components such as atypical larger vesicular nuclei, prominent nucleoli of tumor cells, necrotic foci and mesenchymal collagen proliferation forming the lobular structure, were also appreciated. Immunohistochemally, tumor cells displayed membranous positivity of CD99 (4/4), nuclear positivity of FLI-1 (4/4) and NKX2.2 (4/4), negativity of EMA, GFAP and synaptophysin expression. The histochemical PAS staining showed weak positivity in one case. Fluorescence in situ hybridization (FISH) test using EWSR1 (22q12) dual color break apart rearrangement probe showed positive results in two cases. Results suggest that using a panel of immunohistochemical markers, including NKX2.2, CD99, FLI-1, EMA, GFAP and synaptophysin, combined with the supplementary EWSR1 FISH test, helps to define the diagnosis of meningeal ES/pPNET of CNS.

Immunohistochemical detection of FLI-1 protein expression in Ewing Sarcoma/ peripheral primitive neuroectodermal tumour: A study of 50 cases.

OBJECTIVE: To determine friend leukaemia integration 1 transcription factor protein expression in cases of Ewing sarcoma. METHODS: This retrospective, descriptive study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, and comprised data of diagnosed cases of Ewing sarcoma related to the period from February 2013 to December 2014. Clinico-pathological features, including patient age, gender and site of biopsy were studied. Positivity of immunohistochemical markers such as cluster of differentiation 99(membranous staining) and Friend leukaemia integration 1 transcription factor (nuclear staining) were noted. SPSS17 was used for data analysis. RESULTS: Of the 50 Ewing sarcoma cases, 26(52%) related to women and 24(48%) to men. The overall mean age was 17+11.53 years (range: 3 to 42 years). Moreover, 30(60%) patients had presented with bone swelling or growth whereas 20(40%) had presented with soft tissue swelling. The site of presentation was upper extremities in 16(32%) patients, lower extremities in 14(28%), maxilla in 7(14%), chest wall in 6(12%), paraspinal region in 4(8%), scalp in 2(4%) and retroperitoneum in 1(2%). Membranous positivity for cluster of differentiation 99 was seen in 48(98%) cases. Nuclear positivity for Friend leukaemia integration 1 transcription factor was seen in 39(78%) cases. CONCLUSIONS: Friend leukaemia integration 1 transcription factor was found to be a useful marker in diagnosing Ewing sarcoma/peripheral primitive neuroectodermal tumour. However, its positivity was more dependable when it was used in combination with other markers such as cluster of differentiation 99.

L1-CAM knock-down radiosensitizes neuroblastoma IMR-32 cells by simultaneously decreasing MycN, but increasing PTEN protein expression.

Childhood neuroblastoma is one of the most malignant types of cancers leading to a high mortality rate. These cancerous cells can be highly metastatic and malignant giving rise to disease recurrence and poor prognosis. The proto-oncogene myelocytomatosis neuroblastoma (MycN) is known to be amplified in this type of cancer, thus, promoting high malignancy and resistance. The L1 cell adhesion molecule (L1-CAM) cleavage has been found upregulated in many types of malignant cancers. In the present study, we explored the interplay between L1-CAM, MycN and PTEN as well as the role played by PDGFR and VEGFR on tumorigenicity in neuroblastoma cells. We investigated the effect of L1-CAM knock-down (KD) and PDGFR/VEGFR inhibition with sunitinib malate (Sutent®) treatment on subsequent tumorsphere formation and cellular proliferation and migration in the MycN-amplified IMR-32 neuroblastoma cells. We further examined the effect of combined L1-CAM KD with Sutent treatment or radiotherapy on these cellular functions in our cells. Tumorsphere formation is one of the indicators of aggressiveness in malignant cancers, which was significantly inhibited in IMR-32 cells after L1-CAM KD or Sutent treatment, however, no synergistic effect was observed with dual treatments, rather L1-CAM KD alone showed a greater inhibition on tumorsphere formation compared to Sutent treatment alone. In addition, cellular proliferation and migration were significantly inhibited after L1-CAM KD in the IMR-32 cells with no synergistic effect observed on the rate of cell proliferation when combined with Sutent treatment. Again, L1-CAM KD alone exhibited greater inhibitory effect than Sutent treatment on cell proliferation. L1-CAM KD led to the simultaneous downregulation of MycN, but the upregulation of PTEN protein expression. Notably, radiotherapy (2 Gy) of the IMR-32 cells led to significant upregulation of both L1-CAM and MycN, which was abrogated with L1-CAM KD in our cells. In addition, L1-CAM KD radiosensitized the cells as exhibited by the synergistic effect on the reduction in cell proliferation compared to radiotherapy alone. Taken together, our data show the importance of L1-CAM interplay with MycN and PTEN on the MycN amplified neuroblastoma cell radioresistance, proliferation and motility.

Ewing Sarcoma/Primitive Neuroectodermal Tumor of the Kidney: A Rare and Lethal Entity.

Ewing sarcoma/primitive neuroectodermal tumor represents a spectrum of undifferentiated tumors with similar biology that together represent the second most common sarcoma in the pediatric-young adult age range. Very rarely, this tumor presents as a primary neoplasm of the kidney. The clinical presentation of this tumor is not specific, and other renal tumors may present with a similar histologic appearance. Establishing the correct diagnosis is critical because renal Ewing sarcoma/primitive neuroectodermal tumor carries a strikingly dismal prognosis and thus dictates a specific treatment strategy. A low threshold for the use of ancillary molecular tests is recommended, particularly in diagnostically problematic cases. Important considerations with regards to morphology, immunohistochemistry, and molecular alterations will be reviewed here and should be taken into account before rendering this rare and lethal diagnosis.

MicroRNA-132 dysregulation in Toxoplasma gondii infection has implications for dopamine signaling pathway.

Congenital toxoplasmosis and toxoplasmic encephalitis can be associated with severe neuropsychiatric symptoms. However, which host cell processes are regulated and how Toxoplasma gondii affects these changes remain unclear. MicroRNAs (miRNAs) are small noncoding RNA sequences critical to neurodevelopment and adult neuronal processes by coordinating the activity of multiple genes within biological networks. We examined the expression of over 1000 miRNAs in human neuroepithelioma cells in response to infection with Toxoplasma. MiR-132, a cyclic AMP-responsive element binding (CREB)-regulated miRNA, was the only miRNA that was substantially upregulated by all three prototype Toxoplasma strains. The increased expression of miR-132 was also documented in mice following infection with Toxoplasma. To identify cellular pathways regulated by miR-132, we performed target prediction followed by pathway enrichment analysis in the transcriptome of Toxoplasma-infected mice. This led us to identify 20 genes and dopamine receptor signaling was their strongest associated pathway. We then examined myriad aspects of the dopamine pathway in the striatum of Toxoplasma-infected mice 5days after infection. Here we report decreased expression of D1-like dopamine receptors (DRD1, DRD5), metabolizing enzyme (MAOA) and intracellular proteins associated with the transduction of dopamine-mediated signaling (DARPP-32 phosphorylation at Thr34 and Ser97). Increased concentrations of dopamine and its metabolites, serotonin (5-HT) and 5-hydroxyindoleacetic acid were documented by HPLC analysis; however, the metabolism of dopamine was decreased and 5-HT metabolism was unchanged. Our data show that miR-132 is upregulated following infection with Toxoplasma and is associated with changes in dopamine receptor signaling. Our findings provide a possible mechanism for how the parasite contributes to the neuropathology of infection.

[Small cell malignant tumors of bone: comparison between diagnosis using core needle biopsies and surgical specimens].

OBJECTIVE: To compare the pathologic diagnosis and immunohistochemistry of small cell malignant tumors (SCMT) of bone using both core needle biopsy and surgical specimen. METHODS: Seventy-seven cases of SCMT with core needle biopsies and surgical specimens available were respectively analyzed by histologic examination and immunohistochemical study, with literature review. RESULTS: The male-to-female ratio was 48:29. The age of the patients ranged from 6 to 73 years. The tumors studied included Ewing sarcoma/PNET (n = 38), myeloma (n = 23), lymphoma (n = 10), small cell osteosarcoma (n = 2), small cell carcinoma (n = 2) and mesenchymal chondrosarcoma (n = 2). The tumors involved limbs, axial skeleton and flat bones. Microscopically, the tumors shared similar histology, with small round cells and spindly cells arranged in diffuse sheets. The pathologic diagnosis by core needle biopsies correlated with that by surgical specimens in 84.4% (65/77) of the cases. CONCLUSIONS: SCMT represents a heterogeneous group of malignancy. Correlations with clinicoradiologic findings and application of ancillary investigations including immunohistochemistry and molecular study are important for definitive diagnosis. Pathologic diagnosis using core needle biopsies shows good results and provides useful information for surgical planning.

Clinical and pathological features of primary neuroectodermal tumor/Ewing sarcoma of the kidney.

OBJECTIVE: To collect and analyze clinical and pathological features of primitive neuroectodermal tumor (PNET)/Ewing sarcoma (EWS), a rare tumor occurring most commonly in bone and soft tissues of young people, which rarely occurs as a primary renal neoplasm and exhibits highly aggressive biological behavior. METHODS: All cases of PNET/EWS published from 1975 to February 2012 were collected. When available, clinical and pathological data were extracted for each case. Survivals were estimated with the Kaplan-Meier method and compared with the log-rank test with 95% confidence interval (CI). RESULTS: A total of 116 cases were found. All patients had clinical symptoms as first presentation of disease such as pain (54%), hematuria (29%), and bulky renal mass (28%). Sixty-six percent of patients had stage IV disease at diagnosis. Median disease-free survival (DFS) was 5.0 months (95% CI 2.4-7.6). The probability to be alive at 18 months was 60% and 85% for patients with metastatic disease (M1) or not (M0) at diagnosis, respectively. Median overall survival (OS) was 24 months (95% CI 4.5-15.1) in patients with M1 disease, whereas it was not reached in patients with M0 disease (P <.001). In patients with M0 disease, 50% received neoadjuvant chemotherapy and the 12-month OS was 93% compared to 75% of untreated patients (P = .092). In patients with M1 disease who underwent treatment, the median progression-free survival (PFS) was 22.0 months (95% CI 17.9-26.1) with a clinical benefit in 74% of cases. CONCLUSION: Our findings suggest that PNET/EWS is a rare aggressive tumor affecting principally young people, with a poor prognosis for patients with M1 disease; chemotherapy is an effective strategy in M1 disease and probably also in M0 disease.

Desmoplastic medulloblastoma arising from an ovarian teratoma: a case report and review of the literature.

The primary neuroectodermal tumor of the ovary is extremely rare, and it manifests in 3 forms: differentiated, primitive, and anaplastic. The medulloblastoma belongs to the subgroup of primitive neuroectodermal tumor of the ovary. Only 3 cases of ovarian medulloblastoma have been reported in the literature, and all of them are presented without information about the specific pathological subtype. We present the fourth case of a 26-year-old woman who presented with abdominal fullness for months. Ultrasound exam showed a right adnexal mass with cystic feature and foci solid components. A partial oophorectomy was performed, and the mass was a desmoplastic medulloblastoma arising from an ovarian teratoma.

Primary pulmonary primitive neuroectodermal tumor (PNET): a clinicopathological and immunohistochemical study of six cases.

BACKGROUND: The clinicopathological and immunohistochemical features of six primary pulmonary primitive neuroectodermal tumors (PNETs) are reported. METHODS: The patients were four men and two women aged 22-56 years (mean = 32.3 years). The main presenting symptoms included chest pain, shortness of breath, and cough. The tumor size ranged from 4 to 9.6 cm. RESULTS: Macroscopically, the tumors were circumscribed, yellow-white in color, and of soft and friable consistency. Histologically, the lesions were composed of a monomorphic population of solidly packed round cells with a round-to-ovoid nucleus, fine chromatin, small nucleoli, and scanty pale cytoplasm. Immunohistochemically, the tumor cells were uniformly positive for CD99, neuron-specific enolase, and vimentin, and single cases focally expressed cytokeratin and S100. Fluorescence in situ hybridization analysis performed in two cases showed positive rearrangement for the EWSR1 gene at the 22q12 locus. Follow-up information available for four patients showed that three had died 24-54 months after diagnosis and one patient is alive 11 months after diagnosis. Two patients were lost to follow-up. CONCLUSION: Primary PNETs of the lung are rare tumors that need to be added to the differential diagnosis of primary pulmonary neoplasms composed of small cells. Awareness of this entity as a primary pulmonary neoplasm is required in order to avoid misdiagnosis and unsuitable treatment of patients.

Primitive neuroectodermal tumor/Ewing sarcoma of the retina.

An 11-year-old boy underwent enucleation of his left eye for an intraocular tumor. Examination showed a small, round blue cell tumor arising in the peripheral retina near the ciliary body. Immunohistochemical stain results were positive for neuron-specific enolase, synaptophysin, cluster of differentiation 99 (CD99), Friend leukemia integration 1, and CD56. Ultrastructural findings included occasional intracytoplasmic dense core granules. Polymerase chain reaction of the tumor showed a Ewing sarcoma/Friend leukemia integration gene fusion product. The tumor was classified as a primitive neuroectodermal tumor/Ewing sarcoma of the retina and should be distinguished from retinoblastoma. To our knowledge, this is the first case of primary primitive neuroectodermal tumor of the retina.

Malignant gastrointestinal neuroectodermal tumor: clinicopathologic, immunohistochemical, ultrastructural, and molecular analysis of 16 cases with a reappraisal of clear cell sarcoma-like tumors of the gastrointestinal tract.

The clinical, histologic, immunophenotypic, ultrastructural, and molecular features of a distinctive gastrointestinal tumor are described. Sixteen patients, 8 women and 8 men aged 17 to 77 years (mean age, 42 y; 63% less than 40 y) presented with abdominal pain, intestinal obstruction, and an abdominal mass. Mean tumor size was 5.2 cm (range, 2.4 to 15.0 cm). The tumors arose in the small bowel (10), stomach (4), and colon (2) and were histologically characterized by a sheet-like or nested population of epithelioid or oval-to-spindle cells with small nucleoli and scattered mitoses. Five cases showed focal clearing of the cytoplasm. Scattered osteoclast-type multinucleated giant cells were present in 8 cases. The tumor cells were positive for S-100 protein, SOX10, and vimentin in 100% of cases, for CD56 in 70%, for synaptophysin in 56%, for NB84 in 50%, for NSE in 45%, and for neurofilament protein in 14% of cases. All cases tested were negative for specific melanocytic, gastrointestinal stromal tumors, epithelial, and myoid markers. Ultrastructural examination of 5 cases showed features of primitive neuroectodermal cells with clear secretory vesicles, dense-core granules, occasional gap junctions, and no evidence of melanogenesis. EWSR1 gene rearrangement was assessed by fluorescence in situ hybridization in 14 cases. Twelve cases (86%) showed split EWSR1 signal consistent with a chromosomal translocation involving EWSR1. One case showed extra intact signals, indicating that the nuclei possessed either extra copies of the EWSR1 gene or chromosome 22 polysomy. Only 1 case showed no involvement of the EWSR1 gene. Six cases demonstrated rearrangement of the partner fusion gene ATF1 (46%), and 3 showed rearrangement of CREB1 (23%); 2 cases lacked rearrangement of either partner gene. Clinical follow-up was available in 12 patients and ranged from 1.5 to 106 months. Six patients died of their tumors (mean survival, 32 mo; 83% less than 24 mo). At last follow-up, 4 patients were alive with regional, lymph node, and liver metastases, and 2 patients were alive with no evidence of disease. The tumor described here is an aggressive form of neuroectodermal tumor that should be separated from other primitive epithelioid and spindle cell tumors of the gastrointestinal tract. The distinctive ultrastructural features and absence of melanocytic differentiation serve to separate them from soft tissue clear cell sarcomas involving the gastrointestinal tract. The designation "malignant gastrointestinal neuroectodermal tumor" is proposed for this tumor type.

Extra-osseous Ewing sarcoma of the thyroid gland mimicking lymphoma recurrence: a case report.

Extra-osseous Ewing sarcomas/peripheral primitive neuroectodermal tumors (EOES/pPNETs) are high-grade malignant tumors found in various organs, such as the lung, skin, intestine, kidney and female genital tract; however, to the best of our knowledge, only two cases have previously been identified in the thyroid gland. We describe a case of primary EOES/PNET of the thyroid gland in a 66-year-old man with a previous history of large B cell lymphoma. During a routine follow-up examination, the patient underwent an ultrasound cervical scan showing a solid nodule of the left thyroid lobe. The fine-needle aspiration biopsy of the nodule suggested a neuroendocrine tumor. Histological and immunohistochemical examination of the surgical specimen supported a diagnosis of EOES/PNET, which was further confirmed by the demonstration of EWSR1 gene translocation by means of fluorescent in situ hybridization and by the detection of glycogen particles and neurosecretory granules by means of electron microscopy. Total body computed tomography and magnetic resonance imaging excluded the involvement of other sites, and therefore a diagnosis of primary EOES/PNET of the thyroid gland was made.This paper also discusses the main differential diagnoses, including lymphoma recurrence, other small round cell tumors (primary or metastatic), and a thyroid localization of an EWS/PNET from another organ.

Ewing sarcoma/primitive neuroectodermal tumor of the kidney: clinicopathologic analysis of 34 cases.

The present study describes the clinicopathologic analysis of 34 cases of Ewing sarcoma/primitive neuroectodermal tumor occurring in the kidney. The patients were 21 males and 13 females with an age range of 6 to 44 years. Clinically, patients presented with multiple symptoms including hematuria, pain, and/or lump in the abdomen. Nephrectomy was performed in most of the cases. Grossly, whole of the renal parenchyma was involved by a variegated tumor. Histologically, the tumor was composed of monomorphic, small, and round cells arranged in a variety of patterns. Rosettes, geographical areas of necrosis, and arborizing vascular pattern were the prominent histologic features. The nucleus was monomorphic and round. Anisonucleosis was also noted in some cases. The nucleus was mostly hyperchromatic. A mixture of hyperchromatic and powdery chromatin was noted in few cases. Immunohistochemically, MIC2 (CD99) was positive in 32 of 34 cases followed by neuron-specific enolase (9/12 cases), vimentin (8/14 cases), synaptophysin (1/8 cases), and S-100 protein (1/4 cases). Molecular analysis by reverse transcriptase-polymerase chain reaction that was carried out in 26 cases revealed presence of EWS-FLI-1 type 1 translocation in 12 cases, EWS-FLI-1 type 2 translocation in 10 cases, and both type 1 and type 2 EWS-FLI-1 translocation in 2 cases. Two cases did not demonstrate any translocation. Follow-up data were available for 17 of 34 cases. Local recurrence of the tumor was seen in 4 patients, and 10 patients were recorded to have distant metastasis in various organs, such as lung, bone, and lymph node, during the course of the disease.

[Primitive neuroectodermal tumor in female genital tract: a clinicopathologic study].

OBJECTIVE: To study the clinicopathologic features of primitive neuroectodermal tumor (PNET) in female genital tract. METHODS: Six cases of PNET arising in female genital tract were retrospectively reviewed. The clinicopathologic features, immunohistochemical findings and EWS gene translocation study results were analyzed. RESULTS: The 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. CONCLUSIONS: PNET 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.

CD34 and microtubule-associated protein 2 expression in dysembryoplastic neuroepithelial tumours with an emphasis on dual expression in non-specific types.

AIMS: Three histological variants of dysembryoplastic neuroepithelial tumour (DNT) have been described, namely, simple, complex and non-specific. However, the concept of non-specific variants of DNT remains controversial, because they cannot be accurately distinguished by histological findings alone from ordinary gliomas. The aim was to characterize further the non-specific histological forms of DNT. METHODS AND RESULTS: Forty-one DNTs classified as three histological forms were investigated with CD34 and microtubule-associated protein 2 (MAP2) immunohistochemistry. CD34 immunoreactivity was more frequently observed in non-specific DNT types (16/18 cases; 88.9%) than in classic types (6/23 cases; 26.1%) (P < 0.001). Peritumoral CD34 expression of non-neoplastic cells was significantly associated with CD34-positive tumours (20/22 cases; 90.9%) than with CD34-negative tumours (3/19 cases; 15.8%) (P < 0.001). MAP2 positivity in oligodendroglia-like cells or glial elements was significantly different between classic types and non-specific types (P = 0.025). CD34 and MAP2 immunoreactivities were significantly more frequent in non-specific types (83.3%) than in simple (10%) and complex forms (30.8%) (P < 0.001). CONCLUSIONS: Non-specific DNTs are glioneuronal tumours that have a heterogeneous population of cells with more immature neuronal and glial phenotypes. Furthermore, with regard to practical implications, combined analysis of CD34 and MAP2 is useful in distinguishing DNTs from particularly diagnostically challenging mimics.

Giant extraosseous Ewing sarcoma of the lung in a young adolescent female--a case report.

Extraosseous Ewing sarcoma is a rare soft tissue tumour that is histologically indistinguishable from the bone Ewing sarcoma. The translocation involving chromosome 22 along with CD 99 expression is pathognomonic and is useful in differentiating from other small round cell tumours. Primary lung involvement by this malignant tumour is very uncommon and up to this date only ten cases have been reported. We report a further case in a 15 year-old-female who presented with a huge lung mass causing an opaque haemithorax.

The evaluation of CD99 immunoreactivity and EWS/FLI1 translocation by fluorescence in situ hybridization in central PNETs and Ewing's sarcoma family of tumors.

Ewing's sarcoma family of tumors (ESFTs) are indicated by malignant, small, round and blue cell tumors of the bone and soft tissue. Gene rearrangements between EWS gene on chromosome 22q12 and members of the ETS gene family are common in and specific to ESFTs. Another defining characteristic of ESFTs is their membranous expression of the CD99. In contrast, such translocations and immunoreactivity are not found in central primitive neuroectodermal tumors (cPNETs). The aim of this study was to investigate the detection of EWS/FLI1 translocations and CD99 immunoreactivity in order to evaluate their clinicopathological features and their roles in the differential diagnosis of these tumors. In this study, we investigated CD99 immunoreactivity using immunohistochemistry and Ewing's sarcoma / Friend leukaemia virus integration 1 (EWS/FLI1) translocation using the fluorescence in situ hybridization (FISH) method in 23 cases. CD99 expression was detected in 10/11 (90%) ESFT cases and 2/7 cPNET cases. In 18 cases EWS/FLI1 translocation was examined using the FISH method. The EWS/FLI1 translocations were detected in 7/8 (87.5%) ESFTs cases, whereas non of 8 cPNET cases were detected with this translocation. One case could not be classified as either central or peripheral, showed EWS/FLI1 translocation. There was a statistically significant difference in CD99 expression (p = 0.0013) and EWS/FLI1 translocation (p = 0,002) between cPNETs and ESFTs cases. In conclusion, CD99 expression and EWS/FLI1 translocation are specific and sensitive markers in the diagnosis of ESFTs. However, these were often not found in cases of cPNET. Therefore, in the diagnosis of ESFTs, clinical, radiological, histopathological and immunohistochemical parameters should always be evaluated together.