A practical approach to the clinical diagnosis of Ewing's sarcoma/primitive neuroectodermal tumour and other small round cell tumours sharing EWS rearrangement using new fluorescence in situ hybridisation probes for EWSR1 on formalin fixed, paraffin wax embedded tissue

Selective Immunoreactivity for WT1 Carboxy-Terminus Distinguishes Desmoplastic Small Round Cell Tumor From its Histologic Mimics

Desmoplastic small round cell tumor (DSRCT) is an aggressive pediatric round cell sarcoma containing a characteristic EWSR1-WT1 gene fusion. In the absence of genetic data, distinguishing DSRCT from other small round cell tumors of childhood can be problematic due to overlapping histologic and immunohistochemical features. We studied the utility of immunohistochemistry with antibodies targeting both the amino-terminal and carboxy-terminal regions of the Wilms tumor-1 (WT1) protein in differentiating these groups of tumors. The study cohort included 33 cases of genetically confirmed pediatric round cell tumors (10 DSRCTs, 12 Wilms tumors, 10 Ewing sarcomas, and 1 CIC-rearranged sarcoma). Immunoreactivities and immunolocalization of both the WT1 amino-terminus and carboxy-terminus were scored and documented. All DSRCTs displayed selective reactivity for only the WT1 carboxy-terminus (10/10), while dual immunoreactivity for both the WT1 carboxy-terminus (12/12) and amino-terminus antibodies (12/12) were characteristic of Wilms tumors. CIC-rearranged sarcoma showed variable WT1 nuclear immunopositivity (1/1, 1/1) and Ewing sarcomas were consistently WT1-negative for both the WT1 amino-terminus (0/10) and carboxy-terminus (0/10). Dual WT1 amino-terminus and carboxy-terminus immunohistochemistry remains a helpful diagnostic tool in discriminating intraabdominal small round cell tumors, which serves as an adjunct to the genetic information in preventing misdiagnosis.

Primary desmoplastic small round cell tumor of the submandibular gland: a case report and literature review

Background

Desmoplastic small round cell tumor (DSRCT) is a sporadic, highly malignant tumor with a poor prognosis. The abdomen and pelvis have been reported as the primary localization sites. However, to the best of our knowledge, there are few reports on primary DSRCT in the submandibular gland.

Case presentation

We report a case of a 26-year-old Chinese man with a mass in the right submandibular gland. Imaging studies showed a hypoechoic mass in the right submandibular region. Intraoperative pathology revealed that the tumor tissue was composed of small round tumor cells and a dense desmoplastic stroma. On immunostaining, the tumor cells showed markers of epithelial, mesenchymal, myogenic, and neural differentiation. The EWSR1 gene rearrangement was detected by fluorescence in situ hybridization. Based on the overall morphological features and immunohistochemical findings, a final diagnosis of DSRCT was made. The patient was treated with comprehensive anti-tumor therapy mainly based on radiotherapy and chemotherapy.

Conclusions

DSRCT is an uncommon malignant neoplasm with rare submandibular gland involvement. In this report, we have described a case of DSRCT in the submandibular gland and reviewed the literature on DSRCT over the past 5 years. Considering the importance of differential diagnosis between DSRCT, especially with rare extra-peritoneal involvement, and small round blue cell tumors, a full recognition of the clinicopathological features will help to better diagnose this neoplasm.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13000-021-01183-3.

Recent updates in salivary gland tumors of the lung

Salivary gland tumors are uncommon primary lesions in the lung. Their morphologic, immunophenotypic, and molecular characteristics resemble those of their counterparts in the head and neck or elsewhere. Most common primary pulmonary salivary gland tumors include mucoepidermoid carcinoma, adenoid cystic carcinoma, and epithelial-myoepithelial carcinoma. The study of these neoplasms is hampered by their paucity. Therefore, studies are in general small or restricted to individual cases. Despite this challenge recent advances have been made specifically at the molecular level. Molecular alterations such as MAML2 rearrangements in mucoepidermoid carcinoma, MYB rearrangements in adenoid cystic carcinomas, and EWSR1 rearrangements in hyalinizing clear cell carcinomas and myoepithelial tumors have been identified. These molecular alterations might be helpful in the distinction of these salivary gland tumors from other neoplasms in the lung. However, the distinction from metastatic disease remains challenging. Awareness of these tumors and knowledge of available ancillary studies to confirm the diagnosis is important to avoid misdiagnosis which might lead to differences in treatment, management, and prognosis. Further studies are needed to identify biomarkers to better predict patient's outcome and for individual management and treatment of patients.

Extraskeletal Ewing sarcoma attached to the ulnar nerve: A case report

INTRODUCTION

Extraskeletal Ewing sarcoma (EES) of the extremity is uncommon, and only a small number of reported cases have been devoted to the upper-extremity.

PRESENTATION OF CASE

A 65-year-old woman presented with a recurrent EES, a highly malignant tumor, involving the ulnar nerve at the right elbow region which was initially suspected as a benign soft tissue tumor, schwannoma, thus marginal excision had been performed. Due to its malignant behaviour, we treated the recurrent lesion with wide excision and reconstruction combined with chemotherapy. Histological evaluation revealed a monotonous small round cells appearance.

DISCUSSION

EES of the extremity involving the ulnar nerve is fairly uncommon. The tumor was often smaller in the adult than in the child population which was consistent with the present case, thus may mimic a benign tumor. Because of the overlapping histopathological features of EES with other tumors, other investigations such as immunohistochemistry and cytogenetic studies must be performed to allow definitive diagnosis. The result of our study was negative for the EWSR1-FLI-1 and CIC-DUX4 fusion gene, however, other less frequent translocations could be found in this case which does not exclude the diagnosis of Ewing sarcoma family.

CONCLUSION

Few cases of EES involving the ulnar nerve have been previously reported. The correct diagnosis of EES involving the ulnar nerve has become particularly important in order to enable the initiation of comprehensive management that have the potential to reduce disease progression and the avoidance of improper and potentially harmful surgical therapy.

Mediastinal desmoplastic small round cell tumor

RATIONALE

Desmoplastic small round cell tumor (DSRCT) is a rare distinct tumor with a high-grade malignancy.

PATIENT CONCERNS

A 51-year-old male visited a local hospital in April 2016 complaining of shortness of breath, chest tightness and pain, and exhibited significant swelling in both sides of the chest.

DIAGNOSES

CT demonstrated thoracic symmetry and no abnormalities were observed in the soft tissues of the ribs and the chest wall. A general observation of CT-guided puncture biopsy revealed 2 stripes of gray and grayish-white puncture tissues of 0.5 and 1 cm in length, respectively, and 0.1 cm in diameter. These results preliminarily suggested a (mediastinum) malignant small round cell tumor.

INTERVENTION

Given the progression of the disease, the chemotherapy regimen, consisting of ifosfamide and etoposide, was altered during the course and radiotherapy (total of 70 Gy of mediastinal Y field radiation) was conducted.

OUTCOMES

The patient and his family declined further treatment. Through follow-up, the total survival period was determined as 17 months.

LESSONS

DSRCT is a rare interstitial malignant tumor. Effective cytoreduction combined with comprehensive therapies could achieve partial remission or prolong the survival of patients.

Frequency of Translocation t(11;22)(q24;q12) Using Fluorescence In Situ Hybridization (FISH) in Histologically and Immunohistochemically Diagnosed Cases of Ewing's Sarcoma

Introduction

Ewing sarcoma (ES) family of tumors is one of the most common groups of malignancies arising in children, adolescents, and young adults. Although characteristic histology with immunohistochemical expression of CD99 and FLI1 after exclusion of other small round blue cell tumors is considered diagnostic of ES, frequency of typical ES translocation, i.e., t(11;22)(q24;q12) is not known in our population. Therefore, in this study, we aimed to evaluate the frequency of this translocation in histologically and immunohistochemically diagnosed cases of ES along with its association with other pathological parameters.

Methods

A total of 43 morphologically and immunohistochemically diagnosed cases of ES were included in the study. Fluorescence in situ hybridization (FISH) was performed on representative paraffin blocks to identify t(11;22)(q24;q12) translocation. Association with various clinicopathological characteristics was determined.

Results

Mean age of the patients was 18.23±9.57 years. Bone was the most commonly involved site (22; 51.2%) followed by soft tissue (17; 39.5%) and parenchymal organs (4; 9.3%). A total of 88.4% of cases were found to be FISH-positive for t(11;22)(q24;q12). No significant association of translocation positive cases was noted with tumor size or disease-free survival. Similarly, no significant association of tumor size with disease-free survival was found.

Conclusions

A significant proportion of cases of histologically diagnosed cases of ES exhibited characteristic t(11;22)(q24;q12). This signifies that histology along with immunohistochemistry is reliable for the diagnosis of this tumor; however, in difficult cases, FISH can be performed to detect characteristic translocation. Moreover, we did not find tumor size to be a significant prognostic indicator of survival in ES.

A Nonpediatric Extraosseous Ewing Sarcoma of the Pancreas: Differential Diagnosis and Therapeutic Strategies

Extraosseous Ewing's sarcoma is a rare and aggressive malignant tumor with a poor prognosis. The pancreas is an extremely uncommon primary site, with only 27 cases that have been published worldwide. We report a 26-year-old female who presented with 5 days of left upper quadrant pain, nausea, and vomiting. On examination, she was anicteric and had epigastric and left upper quadrant tenderness without guarding, rebound tenderness, or a palpable mass. She had slightly elevated serum aminotransferase and lipase levels. Abdominal computerized tomography revealed a multilobulated tumor arising from the body and tail of the pancreas. A biopsy confirmed a small round cell tumor, and immunohistochemistry was positive for CD99 in approximately 70% of the tumor cells. A fluorescence in situ hybridization (FISH) assay showed a 22q12 rearrangement. She was diagnosed with extraosseous Ewing sarcoma of the pancreas and underwent multiagent neoadjuvant chemotherapy followed by surgical resection, but subsequent imaging revealed evidence of systemic disease progression. She chose to go on hospice care and died a few weeks later.

Primary bronchial Ewing sarcoma

INTRODUCTION

Primary bronchial Ewing sarcoma (ES) is a rare endobronchial tumor.

PRESENTATION OF CASE

A 65-year-old male presented with six-month history of progressive shortness of breath. Flexible bronchoscopy showed an endobronchial polypoid tumor in the left main stem bronchus about 2 cm from the carina. The tumor was resected by a left bronchial sleeve resection using a right postero-lateral thoracotomy approach. Pathology showed complete tumor resection with negative margins. The morphological and immune-phenotypical features of the resected specimen were compatible with ES. He had an uneventful post-operative recovery. He did not receive adjuvant radiation or chemotherapy and remains disease free at 9 months follow up.

DISCUSSION

A review of the literature identified six other cases of primary bronchial ES. In addition, there were three reported cases of primary ES involving the trachea and thirteen involving the lung parenchyma. Bronchial ES appeared to have a relatively better prognosis than ES involving the trachea or the lung. Our case demonstrates that primary bronchial ES may be treated safely with limited resection, lung preservation and without the need for adjuvant therapy if negative margins can be achieved.

CONCLUSION

Sleeve resection without adjuvant therapy may be a safe treatment option for primary bronchial ES.

Renal primitive neuroectodermal tumor with elevated plasma adrenocorticotropic hormone levels: A case report

Introduction

Primitive neuroectodermal tumors are small round‐cell tumors – Ewing sarcoma family, frequently occurring in the extremities, but rarely in the kidney.

Case presentation

A 58‐year‐old woman presented with whole‐body edema and weakness of lower limb muscles. Computed tomography revealed a left renal tumor, and the plasma adrenocorticotropic hormone level was elevated. The tumor was surgically removed without complications, her plasma adrenocorticotropic hormone reverted to normal levels, and symptoms disappeared after surgery. Histopathological examination revealed a primitive neuroectodermal tumor arising in her kidney. The patient was alive without metastasis 3 years after the surgery.

Conclusion

We report the first case of renal primitive neuroectodermal tumor accompanying elevated plasma adrenocorticotropic hormone levels which are thought to be produced and secreted in an ectopic fashion.

[Histopathology and molecular profile of a case of prostatic Ewing sarcoma]

We report a case of Ewing sarcoma localized in the prostate gland of a 33-year-old patient without bone or soft tissue involvement. Evidence of EWS and FLI1 gene translocation was detected by fluorescence in situ hybridization (FISH). This is an unusual case with an interesting clinical presentation; indeed, only a few cases have been reported to date and not all have the supporting biological studies now considered essential for the diagnosis.

Myxoid liposarcoma with cartilaginous differentiation showing DDIT3 rearrangement

Myxoid liposarcoma (MLPS) is the second most common histologic subtype of liposarcoma. However, cartilaginous differentiation within MLPS is an extremely rare phenomenon, with only 7 cases of MLPS with cartilaginous differentiation reported to date. The majority of MLPS cases show the t(12;16)(q13;p11) translocation, resulting in the fused in sarcoma-DNA damage-inducible transcript 3 (FUS-DDIT3) fusion gene. This fusion gene as a hallmark of MLPS is very useful for differential diagnosis from other soft tissue sarcomas, and the associated protein, FUS-DDIT3, performs an important role in the phenotypic selection of targeted multipotent mesenchymal cells during oncogenesis. In this report, a case of MLPS with cartilaginous differentiation that occurred in the thigh of a 44-year-old woman is described. Histopathologically, the tumor was composed of a typical myxoid liposarcoma area and a mature hyaline cartilaginous area. Using fluorescence in situ hybridization analysis, rearrangement of the DDIT3 gene was detected in not only the liposarcomatous area but also in the chondrocytes of the cartilaginous area. Based on these findings, the cartilaginous differentiation area appears to be partially associated with oncogenesis through the specific fusion gene FUS-DDIT3.

Desmoplastic small round cell tumor: evaluation of reverse transcription-polymerase chain reaction and fluorescence in situ hybridization as ancillary molecular diagnostic techniques

Desmoplastic small round cell tumor (DSRCT) is a rare, biologically aggressive soft tissue neoplasm of uncertain differentiation, most often arising in the abdominal and pelvic cavities of adolescents and young adults with a striking male predominance. Histologically, it is characterized by islands of uniform small round cells in prominent desmoplastic stroma, and it has a polyimmunophenotypic profile, typically expressing WT1 and cytokeratin, desmin, and neural/neuroendocrine differentiation markers to varying degrees. Tumors at other sites and with variant morphology are more rarely described. DSRCT is associated with a recurrent t(11;22)(p13;q12) translocation, leading to the characteristic EWSR1-WT1 gene fusion. Fluorescence in situ hybridization (FISH), to detect EWSR1 rearrangement, and reverse transcription-polymerase chain reaction (RT-PCR) to assess for EWSR1-WT1 fusion transcripts are routine diagnostic ancillary tools. We present a large institutional comparative series of FISH and RT-PCR for DSRCT diagnosis. Twenty-six specimens (from 25 patients) histologically diagnosed as DSRCT were assessed for EWSR1 rearrangement and EWSR1-WT1 fusion transcripts. Of these 26 specimens, 24 yielded positive results with either FISH or RT-PCR or both. FISH was performed in 23 samples, with EWSR1 rearrangement seen in 21 (91.3%). RT-PCR was performed in 18 samples, of which 13 (72.2%) harbored EWSR1-WT1 fusion transcripts. The sensitivity of FISH in detecting DSRCT was 91.3%, and that of RT-PCR was 92.8% following omission of four technical failures. Therefore, both methods are comparable in terms of sensitivity. FISH is more sensitive if technical failures for RT-PCR are taken into account, and RT-PCR is more specific in confirming DSRCT. Both methods complement each other by confirming cases that the other method may not. In isolation, FISH is a relatively non-specific diagnostic adjunct due to the number of different neoplasms that can harbor EWSR1 rearrangement, such as Ewing sarcoma. However, in cases with appropriate morphology and a typical pattern of immunostaining, FISH is confirmatory of the diagnosis.

Cytogenetically confirmed primary Ewing's sarcoma of the pancreas

Ewing's sarcoma is a highly aggressive malignant tumour most commonly affecting long bones in children and adolescents. It is part of the Ewing's sarcoma family of tumours (ESFTs) that also include peripheral primitive neuroectodermal tumour and Askin's tumours. ESFTs share common cytogenetic aberrations, antigenic profiles and proto-oncogene expression with an overall similar clinical course. In 99% of ESFTs, genetic translocation with molecular fusion involves the EWSR1 gene on 22q12. Approximately 30% of ESFTs are extraosseous, most commonly occurring in the soft tissues of extremities, pelvis, retroperitoneum and chest wall. Primary presentation in solid organs is very rare but has been described in multiple sites including the pancreas. Accurate diagnosis of a Ewing's sarcoma in a solid organ is critical in facilitating correct treatment. We report the case of a 17-year-old girl with cytogenetically confirmed primary pancreatic Ewing's sarcoma and provide a brief review of the published literature.

Ewing's Sarcoma as a Second Malignancy in Long-Term Survivors of Childhood Hematologic Malignancies

Modern multimodal treatment has significantly increased survival for patients affected by hematologic malignancies, especially in childhood. Following remission, however, the risk of developing a further malignancy is an important issue. The long-term estimated risk of developing a sarcoma as a secondary malignancy is increased severalfold in comparison to the general population. Ewing's sarcoma family encompasses a group of highly aggressive, undifferentiated, intra- and extraosseous, mesenchymal tumors, caused by several types of translocations usually involving the EWSR1 gene. Translocation associated sarcomas, such as Ewing sarcoma, are only rarely encountered as therapy associated secondary tumors. We describe the clinical course and management of three patients from a single institution with Ewing's sarcoma that followed successfully treated lymphoblastic T-cell leukemia or non-Hodgkin lymphoma. The literature on secondary Ewing's sarcoma is summarized and possible pathogenic mechanisms are critically discussed.

Diagnosis of desmoplastic small-round-cell tumor by cytogenetic analysis: a case report

We herein present atypical histologic and immunohistochemical features of DSRCT. The various differential diagnoses of DSRCT may occasionally generate confusion. Cytogenetic analysis may solve diagnostic dilemmas such as that in our case. Further studies are required to establish a standard treatment for DSRCT.

A peripheral primitive neuroectodermal tumor originating from the pancreas: a case report and review of the literature

A peripheral primitive neuroectodermal tumor (pPNET) is a small round cell tumor occurring mostly in children or young adults and categorized into the Ewing sarcoma family of tumors. pPNETs originating from the pancreas are especially rare, and only 25 cases have been reported in the literature. We report a case of a 22-year-old man who had a giant expansive tumor located in the uncinate process of the pancreas, 80 mm in diameter resulting in obstruction in the duodenum. The patient underwent a pancreaticoduodenectomy. The histological examination showed that the pancreatic tumor was composed of atypical small round cells. Immunohistochemical findings were positive for CD99. An Ewing sarcoma breakpoint region 1 gene 22q12 rearrangement was proven by a two-color fluorescence in situ hybridization assay. We diagnosed the tumor as a pPNET of the pancreas, which, according to the literature, is highly aggressive with poor prognosis. A multidisciplinary approach to treat these neoplasms should improve the prognoses.

Application of electron microscopic analysis and fluorescent in situ hybridization technique for the successful diagnosis of extraskeletal Ewing's sarcoma

The diagnosis of soft tissue tumors is often challenging. Immunohistochemical investigation, let alone routine histopathological investigation, may not allow definitive diagnosis in some cases. To overcome such difficulties, more advanced techniques need to be adopted. Herein, we report an extremely rare 56-year-old Japanese female case of extraskeletal Ewing's sarcoma (ES), successfully diagnosed by electron microscopy (EM) using formalin-fixed sections and fluorescence in situ hybridization (FISH). The patient had a 2-year history of a tumor growing on the leg. In routine histopathology, invasive proliferation of tumor cells was observed in the dermis. Tumor cells were round and uniform with large hyperchromatic nuclei, which were positively stained for CD56, VS38c, Ki-67, MIC2 and vimentin, but not for pan-keratin AE1 + AE3, cytokeratin 20, chromogranin A, synaptophysin and neuron-specific enolase. As these findings were not conclusive to make the final diagnosis, EM specimens were prepared from formalin-fixed sections and subjected to investigation. Cell surface projections and dense core granules were detected, suggestive of either Merkel cell carcinoma or extraskeletal ES. Subsequent FISH analysis identified reciprocal translocation of the ESWR1 gene, enabling the final diagnosis of extraskeletal ES. This study provides useful information enabling the diagnosis of this uncommon soft tissue tumor.

Nasopharyngeal hyalinizing clear cell carcinoma with EWSR1 rearrangements diagnosed by fluorescence in situ hybridization

Hyalinizing clear cell carcinoma (HCCC) is a rare, low-grade salivary gland neoplasm with a predilection for the palate and tongue. A 63-year-old woman presented a 14×14×17-mm mass at the roof of the nasopharynx. Endoscopic resection was performed via a transnasal approach. Histopathological findings of the salivary gland tumor indicated hyalinization of the stroma and neoplastic cells with clear cytoplasm without mucin. Fluorescence in situ hybridization analysis revealed that the tumor cells were positive for EWSR1 rearrangement. We finally diagnosed this case as HCCC of the nasopharynx. EWSR1 rearrangements are non-existent in other salivary gland tumors with clear cell change; thus, the identification of this rearrangement was very useful in accurately diagnosing HCCC.

Molecular strategies for detecting chromosomal translocations in soft tissue tumors (review)

Approximately one third of soft tissue tumors are characterized by chromosomal aberrations, in particular, translocations and amplifications, which appear to be highly specific. The identification of fusion transcripts not only supports the diagnosis, but provides the basis for the development of novel therapeutic strategies aimed at blocking the aberrant activity of chimeric proteins. Molecular biology, and in particular, cytogenetic and qualitative and quantitative polymerase chain reaction technologies, allow with high efficiency and specificity, the determination of specific fusion transcripts resulting from chromosomal translocations, as well as the analysis of gene amplifications. In this review, various molecular techniques that allow the identification of translocations and consequent fusion transcripts generated are discussed in the broad spectrum of soft tissue tumors.

Two Cases of Spinal, Extraosseous, Intradural Ewing's sarcoma/Peripheral Neuroectodermal Tumor: Radiologic, Pathologic, and Molecular Analysis

Extraosseous Ewing's sarcoma/peripheral neuroectodermal tumors (ES/PNETs) are rare neoplasms that account for approximately 10%-15% of soft tissue sarcomas in children and 5% of soft tissue sarcomas in adults. Primary spinal, extraosseous, intradural ES/PNETs are even less common. The diagnosis of ES/PNET is extremely challenging, because the tumor can have a nonspecific radiologic appearance, and the histologic features are shared by many other "small round cell tumors." Thus, ES/PNET should be included in the radiologic and pathologic differential diagnosis, even in older patients and in unusual tumor sites. We report two cases of spinal, extraosseous, intradural ES/PNETs in adults who presented with back pain. Magnetic resonance imaging revealed contrast enhancing, intradural lesions in the area of the conus medullaris. The tumor in Case 1 was partially intramedullary, while the tumor in Case 2 was exclusively extramedullary. In both cases, the radiologic and intraoperative surgical impression favored ependymoma. The diagnosis of ES/PNET was established in both cases by histopathologic, immunohistochemical, and molecular analysis.

Usefulness of a monoclonal ERG/FLI1 antibody for immunohistochemical discrimination of Ewing family tumors

Ewing family tumors (EFTs) and prostate carcinomas are characterized by rearrangement of ETS genes, most commonly FLI1 (EFTs) and ERG (prostate carcinomas). Previously, we characterized an antibody against ERG (EPR3864) for detecting ERG-rearranged prostate carcinoma. Because EPR3864 also cross-reacts with FLI1, we evaluated the usefulness of EPR3864 for discriminating EFTs from other small round blue cell tumors (SRBCTs) with immunohistochemistry. Of 57 evaluable EFTs, 47 (82%) demonstrated at least moderate, diffuse, nuclear ERG/FLI1 staining (including 89% and 100% of cases with confirmed EWSR1:FLI1 and EWSR1:ERG fusions, respectively), of which 1, 3, and 43 showed negative, cytoplasmic, or membranous CD99 staining, respectively. Among other SRBCTs (61 cases, 7 types), at least moderate, diffuse, nuclear EPR3864 staining was seen in all precursor B-lymphoblastic lymphomas/leukemias and subsets of Burkitt lymphomas (10%) and synovial sarcomas (45%). In summary, EPR3864 may be useful in detecting EWSR1:FLI1 and EWSR1:ERG rearranged EFTs in addition to prostate carcinomas.

Small Round Cell Tumors of Bone

Diagnosing small round cell tumors (SCRTs) can be a difficult task for pathologists due to overlapping clinicopathologic features. This review highlights the clinical, radiographic, histologic, immunohistochemical, and genetic features of the most common SRCTs involving bone with an emphasis on differential diagnosis. SRCTs are a heterogeneous group of neoplasms characterized by poorly differentiated cells with small, blue, round nuclei and scant cytoplasm. They can occur as primary tumors in bone or soft tissue.

Paratesticular desmoplastic small round cell tumour: an unusual tumour with an unusual fusion; cytogenetic and molecular genetic analysis combining RT-PCR and COBRA-FISH

Desmoplastic small round cell tumour is a rare malignant tumour with a male to female ratio of 4:1. It manifests mostly at serosal sites. Here we present a case of a 28-year-old male patient, who presented with a fast growing paratesticular mass. On biopsy nests and cords of small round cells, without a clear morphological lineage of differentiation were seen. Occasionally desmoplatic small round cell tumour shows different lines of differentiation. An unequivocal histological diagnosis might be difficult in such cases. Here we demonstrate by a combination of methods the characteristic immunohistochemical profile and - albeit unusual - molecular background and discuss the eventual link with Ewing sarcoma.Immunohistochemical studies showed a membranous staining of Keratine AE1/3 and a dot-like staining of Desmine, confirming its diagnosis. Using COBRA-FISH following a metaphase approach we demonstrated a balanced translocation, t(11;22)(p13;q12) and in RT-PCR formation of the EWSR1-WT1 fusion product, a specific translocation of desmoplastic round cell tumour. The fusion involves exon 9 of EWSR1 to exon 8 of WT1, an unusual fusion product, though earlier described in a case of a desmoplastic small round cell tumour of the hand. The EWSR1-WT1 chimera seems to function as an oncogenic transcription factor. Here the zinc finger domain of the WT1 acts with affinity with certain promoter domains influencing the expression of various downstream proteins such as: PDGFA, PAX2, insulin-like growth factor 1 receptor, epidermal growth factor receptor, IL2 receptor beta, BAIAP3, MLF1, TALLA-1, LRRC15 and ENT. We discuss their potential oncogenic roles and potential therapeutic consequences.

Diagnostic utility of EWS break-apart fluorescence in situ hybridization in distinguishing between non-cutaneous melanoma and clear cell sarcoma

Clear cell sarcoma (CCS) is a rare soft tissue sarcoma with morphological similarities to malignant melanoma (MM), but with a distinct genetic background that includes the chromosomal translocation t(12;22)(q13;q12). Clear cell sarcoma is often misdiagnosed as MM because of similarities in target locations and immunophenotypes. Eighteen cases with MM in non-cutaneous sites were subjected to fluorescence in situ hybridization (FISH) to assess EWS gene breakage. Tissue microarrays were constructed using formalin-fixed, paraffin-embedded tissue and the EWSR1 (22q12) dual-color, break-apart rearrangement probe (Vysis) was used. Two patients were classified as CCS with EWS gene rearrangement, with a mean of 67.5% positive cells per sample according to break-apart FISH. The remaining 16 patients lacked break-apart signals of the EWS gene. The presence of type 1 (EWS exon 8-ATF1 exon 4) fusion transcripts was confirmed in FISH-positive patients by RT-PCR. Retrospective analysis revealed that the masses were located in the foot and buttock, respectively. Morphologically, tumor cells were not typical for those of CCS or MM. Break-apart FISH is an accurate and convenient method for differentiating between MM and CCS. Molecular detection of EWS gene rearrangement, either by break-apart FISH or RT-PCR, is mandatory in subjects with melanotic tumors of soft tissue.

Primary tracheal Ewing's sarcoma

Ewing's sarcoma is a malignant neoplasm usually occurring in the long and flat bones of children and adolescents. Extraskeletal Ewing's sarcoma is extremely rare, and we believe this has not been described previously in the trachea. We report a case of primary tracheal Extraskeletal Ewing's sarcoma that presented with acute airway obstruction. Stabilization of the airway was accomplished through a rigid bronchscopy, followed by debridement and stenting. The patient then underwent neoadjuvant chemotherapy followed by tracheal resection. Our case highlights the management of a tracheal mass and the multidisciplinary approach required for definitive treatment.

Ewing Sarcoma Family of Tumors

The diagnosis and management of Ewing sarcoma is laborious and requires the correlation of multiple imaging modalities. This is an aggressive, malignant tumor of bone and soft tissue. Ewing sarcoma rarely affects individuals older than 20 years of age. Clinical symptoms are variable and nonspecific. Biopsy is the only definitive diagnosis. Multimodality medical imaging plays a great role in visualizing the tumor, documenting metastatic spread, tumor staging, associated complications, and response to therapy. Standard treatment of Ewing sarcoma is a multimodal therapeutic regimen, including chemotherapy, surgery, and radiation. Prognosis depends on tumor location, presence of metastases, and tumor size.

Primitive neuroectodermal tumors in patients with testicular germ cell tumors usually resemble pediatric-type central nervous system embryonal neoplasms and lack chromosome 22 rearrangements

Primitive neuroectodermal tumors (PNETs) are one of the most frequent types of 'non-germ cell' tumor in patients with testicular germ cell tumors and have a guarded prognosis when present in metastatic sites after cisplatin-based chemotherapy. Improved treatments, including targeted therapy, require understanding the biology of these neoplasms. We therefore analyzed the morphologic, immunohistochemical and molecular biologic features of 14 PNETs from 14 patients with concurrent or previous testicular germ cell tumors; 12 tumors were from metastatic sites and 2 were primary in the testis. Using standard light microscopic criteria for central nervous system and peripheral PNETs, we classified nine tumors as medulloepithelioma, three as medulloblastoma/supratentorial PNET, one as neuroblastic tumor with abundant neuropil and true rosettes and one as small cell embryonal tumor/PNET (Ewing sarcoma-like). Immunostains directed against INI1, CD57, S-100 protein, NeuN, WT1, neurofilament, CD99, GFAP, synaptophysin, chromogranin, AE1/AE3 cytokeratin, Fli-1 and collagen IV were performed for each case. INI1 was diffusely and strongly positive in all tumors whereas the other stains, except for cytoplasmic WT1 (which showed substantial reactivity in most tumors), were mostly focal to negative, including CD99 (eight negative, six focal) and Fli-1 (all negative). The most consistently reactive 'neuroendocrine' marker was CD57. Each case was also analyzed for chromosome 22 rearrangements using a FISH-based break-apart probe method. Only 1 tumor, classified as medulloepithelioma, was scored positive for chromosome 22 translocation (22% rearranged cells) and the remaining 13 were negative, including the one case that resembled peripheral PNET. We conclude that PNETs derived from testicular germ cell tumors mostly resemble central nervous system PNETs and generally lack the chromosome 22 translocation of peripheral PNETs. Future treatment strategies should take these findings into account.

Histological heterogeneity of Ewing's sarcoma/PNET: an immunohistochemical analysis of 415 genetically confirmed cases with clinical support

Ewing's sarcoma (ES)/peripheral neuroectodermal tumor (PNET) are malignant neoplasms affecting children and young adults. We performed a study to typify the histological diversity and evaluate antibodies that may offer diagnostic/prognostic support. In total, 415 cases of genetically confirmed paraffin-embedded ES/PNET were analyzed on whole sections and in tissue microarrays. This study confirms the structural heterogeneity of ES/PNET, distinguishing three major subtypes: conventional ES (280 cases); PNET (53 cases); and atypical ES/PNET (80), including large cells, vascular-like patterns, spindle pattern, and adamantinoma-like configuration. All cases presented positivity for at least three of the four tested antibodies (CD99, FLI1, HNK1, and CAV1). CAV1 appeared as a diagnostic immunomarker of ES/PNET being positive in CD99-negative cases. Hence, the immunohistochemical analysis confirmed the diagnostic value of all four antibodies, which together cover more than 99% of the tumors, independently of the histological variety. The univariate analysis for survival revealed atypical ES as the only histological parameter apparently associated with less favorable clinical outcome, particularly in the subgroup of patients treated with surgery. In conclusion, the diagnosis of atypical ES is a challenge for the pathologist and needs support from molecular techniques to perform an optimal differential diagnosis with other small round cell tumors.

Superficial primitive Ewing's sarcoma: a clinicopathologic and molecular cytogenetic analysis of 14 cases

Superficial primitive Ewing's sarcomas are rare and have been reported to be of favorable prognosis compared to conventional deep-seated tumors. In the skin and subcutis, the diagnosis is often difficult, and performing molecular cytogenetic techniques may be helpful. We performed a retrospective analysis of 14 cases of superficial Ewing's sarcomas, all confirmed by molecular cytogenetics. Clinical, histological, immunohistochemical, molecular cytogenetic, therapeutic, and follow-up data are reported. There were 11 female and 3 male patients aged from 12 to 77 years (median: 17 years). Seven tumors occurred in the extremities, five in the trunk wall, and two in the head. Tumor size ranged from 1 to 5 cm (median, 3 cm). They were all small round-cell proliferations with a strong membranous positivity for CD99. Ewing's sarcoma translocations/fusion gene transcripts were detected in eight cases, both by FISH and reverse transcriptase (RT)-PCR. Four tumors were positive by RT-PCR alone (FISH not done in three cases and not interpretable in one case), and two cases were positive by FISH alone (RT-PCR not done). Surgical resection was performed in all patients. Chemotherapy was given in ten patients and radiotherapy in six. At last medical examination (median follow-up, 47 months), two patients who underwent surgical resection alone had died from the tumor. Our results confirm that superficial Ewing's sarcomas are of good prognosis. Given the difficulty of the diagnosis and the importance of an adapted treatment, a confirmation of the diagnosis by molecular or cytogenetic techniques is recommended when dealing with a superficial tumor.

Primitive neuroectodermal tumor of the pancreas

The primitive neuroectodermal tumor (PNET) of the pancreas, a member of Ewing's sarcoma family of tumors, is extremely rare. We treated a 37-year-old Japanese man who had a solitary pancreatic tumor 40 mm in diameter and multiple hepatic tumors with surgical resection. The PNET was positive for CD99 on immunohistochemical staining. Fluorescence in situ hybridization (FISH) was also performed, which revealed a Ewing sarcoma breakpoint region 1 (EWSR1) 22q12 rearrangement. According to the Japan-Ewing protocol, chemotherapy with Ifomide (ifosfamide), etoposide, vincristine, and cyclophosphamide was given after surgery. To the best of our knowledge, to date 13 PNET cases have been reported with a mean age for all patients of 19.3 years old. Surgical resection was performed in most cases and some patients received postoperative chemotherapy. The clinicopathologic characteristics and management of this extremely rare disease are also discussed.

PAX--FKHR fusion genes and AChR-gamma in Chinese patients with rhabdomyosarcoma: diagnosis using formalin-fixed archival tissues

The majority of alveolar RMSs have t(2;13)(q35;q14) or (1:13)(p36;q14),which generate PAX3/7 -FKHR fusion genes. Here, the authors detected the PAX3/7-FKHR fusion transcripts in 17 formalin-fixed, paraffin-embedded RMSs and 26 other SRCTs using one-step RT-PCR. PAX3 -FKHR and PAX7-FKHR transcripts were positive in 4/8 and 2/8 cases of ARMS, respectively. 9 ERMSs and 26 other SRCTs were negative for PAX3/7-FKHR. In addition, AChR-gamma and AChR-alpha mRNA were detected by semiquantitative duplex PCR in above cases and 3 normal muscles. 17 RMSs were found to have overexpression of AChR-gamma, with an AChR-gamma/-alpha ratio of > or =1; 3 cases of normal muscle had very weak AChR-gamma expression, with an AChR- gamma/-alpha ratio of <1. AChR-gamma transcripts were not detectable in all 26 other SCRTs. The results demonstrated that detection of PAX3/7-FKHR fusion gene by one-step RT-PCR is useful in the diagnosis of RMS and that AChR-gamma is overexpressed in Chinese RMS patients.

[Case report of a subcutaneous peripheral primitive neuroectodermal tumor]

Peripheral primitive neuroectodermal tumors - also known as Ewing sarcomas - are a rare type of malignant tumor the histology of which characteristically reveals the presence of small round cells. Typically, t(11;22) translocation is observed. We describe the case of a 45-year-old man with a subcutaneous peripheral primitive neuroectodermal tumor in which the t(11;22) translocation was detected. He was satisfactorily treated with surgery and radiotherapy.

Gastrointestinal melanoma or clear cell sarcoma? Molecular evaluation of 7 cases previously diagnosed as malignant melanoma

Clear cell sarcoma (CCS) is a rare tumor classically associated with the tendons and aponeuroses of distal extremities of young adults. CCS and malignant melanoma (MM) share immunohistochemical profiles and ultrastructural features, but classic CCS has characteristic morphology with low mitotic activity and minimal pleomorphism. Occasional cases show pleomorphism, high mitotic index, and/or melanin pigmentation, making CCS indistinguishable from MM based on morphology. However, CCS is genetically distinct owing to its consistent association with a t(12;22)(q13;q12) chromosomal translocation, leading to the formation of the EWS/ATF1 fusion transcript. This translocation has never been documented in cutaneous melanoma, and thus is regarded as specific for CCS. Recent evidence suggests that primary "malignant melanomas" in unusual anatomic sites, most notably the gastrointestinal (GI) tract, may be CCS. This is supported by 11 cases of primary GI CCS with the t(12;22) translocation. We used reverse-transcription polymerase chain reaction and fluorescence in situ hybridization to examine whether a proportion of cases diagnosed as MM of the GI tract in patients without a history of cutaneous MM actually represent primary GI CCS. In total, we examined 7 cases: Four with no prior history of MM, 2 with histories of cutaneous MM, and 1 with an anal MM. All 4 cases for which there was no history of cutaneous/mucosal MM harbored the EWS/ATF1 fusion transcript. We report the largest series of GI CCS and have shown that molecular studies may be warranted in cases that otherwise seem to represent MM of unusual primary locations.

Prediction of response and prognostic factors for Ewing family of tumors in a low incidence population

PURPOSE

There is some unknown reason Ewing family of tumors (EFTs) is much less common on Asia and Africa than in the Western Caucasian population. This study analyzed the prediction of response and prognostic factors for Ewing family of tumors (EFTs) in an Asian population with a low incidence.

METHODS

We retrospectively reviewed 94 patients with EFTs between 1978 and 2006. Fifteen patients received local therapy only. Statistical analyses were performed for 79 patients, including those who received systemic chemotherapy, to identify factors related to chemotherapy responsiveness, event-free survival, and overall survival.

RESULTS

Of the 79 patients whose records were analyzed, the 5-year event-free rate and overall survival (OS) rate were 41 and 54%, respectively. The response rate to first-line chemotherapy was 61% in 70 patients with assessable lesions. A significant predictor of response was existence of a non-pelvic primary tumor (P = 0.04). Significant prognostic factors for OS were age, performance status, and metastases at the time of diagnosis (P < 0.01, respectively). Fifty-four patients had disease progression or recurrence after first-line treatment. The time to progression was 3.4 months after salvage treatment. Progression during first-line treatment was significantly associated with time to progression after salvage treatment (P = 0.01). All patients treated without chemotherapy in first-line treatment were recurred with poor prognosis.

CONCLUSION

A non-pelvic primary tumor was a favorable predictor of responsiveness to chemotherapy. Chemo-resistant patients might less benefit from second line chemotherapy. Chemotherapy in first-line treatment should not be omitted, even if primary tumor was extirpated completely.

Differentiating Ewing's sarcoma from other round blue cell tumors using a RT-PCR translocation panel on formalin-fixed paraffin-embedded tissues

Ewing's sarcoma is a common malignancy of bone and soft tissue that occurs most often in children and young adults. Differentiating Ewing's sarcoma from other round blue cell tumors can be a diagnostic challenge because of their similarity in histology and clinical presentation. Thus, ancillary molecular tests for detecting disease-defining translocations are important for confirming the diagnosis. We analyzed 65 round blue cell tumors, including 53 Ewing's sarcoma samples from 50 unique cases. Samples were processed for RNA from archived formalin-fixed paraffin-embedded tissue blocks. Real-time RT-PCR assays specific for Ewing's sarcoma (EWS-FLI1, EWS-ERG, EWS-ETV1, EWS-ETV4, and EWS-FEV), synovial sarcoma (SYT-SSX1 and SYT-SSX2), and rhabdomyosarcoma (PAX3-FKHR and PAX7-FKHR) were tested across the samples. The translocation panel had a sensitivity of 81% (43 out of 53 samples) for diagnosing Ewing's sarcoma when using the histological criteria as the 'gold' standard. None of the Ewing's specific translocations were found in the non-Ewing's samples (100% specificity). Of the 43 samples with translocations detected, 26 (60%) had an EWS-FLI1 type 1 translocation, 13 (30%) had an EWS-FLI1 type 2 translocation, 3 (7%) had an EWS-ERG translocation, 1 had an EWS-ETV1 translocation, and 1 sample had both an EWS-FLI1 type 1 and type 2 translocation. Our real-time RT-PCR assay for detecting sarcoma translocations has high sensitivity and specificity for Ewing's sarcoma and has clinical utility in differentiating small round blue cell tumors in the clinical lab.

Comparative analysis of routine histology, immunohistochemistry, reverse transcriptase polymerase chain reaction, and fluorescence in situ hybridization in diagnosis of Ewing family of tumors

CONTEXT

The Ewing family of tumors are often difficult to distinguish from other malignant small round cell tumors, but more than 90% have EWS-FLI1 chimeric transcript, which acts as a potential molecular diagnostic marker.

OBJECTIVE

To do a comparative analysis of 32 cases with EWS-FLI1: Ewing family of tumors (n = 30), desmoplastic small round cell tumor (n = 1), and undifferentiated sarcoma (n = 1).

DESIGN

The initial diagnosis was made on core biopsy (n = 22) and open biopsy (n = 4) specimens by using morphology and immunohistochemistry and on fine-needle aspiration cytology ([FNAC], n = 6) specimens. EWS-FLI1 was detected by reverse transcriptase polymerase chain reaction on all 32 fresh FNAC samples and by fluorescence in situ hybridization on 16 paraffin blocks.

RESULTS

The 19 male and 13 female patients had bone (n = 19) or soft tissue (n = 13) tumors. Histologic groups were typical Ewing sarcoma (n = 15), atypical Ewing sarcoma (n = 4), Askin Rosai tumors (n = 5), desmoplastic small round cell tumor (n = 1), undifferentiated sarcoma (n = 1), and cases diagnosed as malignant small round cell tumors on FNAC (n = 6). All tumors except desmoplastic small round cell tumor and undifferentiated sarcoma were CD99 positive. EWS-FLI1 by reverse transcriptase polymerase chain reaction was noted in 15 cases of typical Ewing sarcoma, 4 cases of atypical Ewing sarcoma, 5 cases of Askin Rosai tumor, and no cases of desmoplastic small round cell tumor or undifferentiated sarcoma. With use of fluorescence in situ hybridization, EWS break was detected in 10 of 11 paraffin blocks used and was negative in desmoplastic small round cell tumor.

CONCLUSIONS

The excellent correlation of routine histologic findings in Ewing family of tumors with results on immunohistochemistry and fluorescence in situ hybridization on archival material and reverse transcriptase polymerase chain reaction on fresh FNAC specimens underscores that the traditional observation on routine histologic examination is a time-tested tool. The diagnosis of Ewing family of tumors can be validated on archival material or fresh biopsy samples, including those obtained by FNAC.

A novel type of EWS–CHOP fusion gene in myxoid liposarcoma

The cytogenetic hallmark of myxoid type and round cell type liposarcoma consists of reciprocal translocation of t(12;16)(q13;p11) and t(12;22)(q13;q12), which results in fusion of TLS/FUS and CHOP, and EWS and CHOP, respectively. Nine structural variations of the TLS/FUS-CHOP chimeric transcript have been reported, however, only two types of EWS-CHOP have been described. We describe here a case of myxoid liposarcoma containing a novel EWS-CHOP chimeric transcript and identified the breakpoint occurring in intron 13 of EWS. Reverse transcription-polymerase chain reaction and direct sequence showed that exon 13 of EWS was in-frame fused to exon 2 of CHOP. Genomic analysis revealed that the breaks were located in intron 13 of EWS and intron 1 of CHOP.