Cluster analysis of immunohistochemical profiles in synovial sarcoma, malignant peripheral nerve sheath tumor, and Ewing sarcoma.

As a result of overlapping morphologic and immunohistochemical features, it can be difficult to distinguish synovial sarcoma, malignant peripheral nerve sheath tumor, and Ewing sarcoma/primitive neuroectodermal tumor in core biopsies. To analyze and compare immunohistochemical profiles, we stained tissue microarrays of 23 synovial sarcomas, 23 malignant peripheral nerve sheath tumors, and 27 Ewing sarcomas with 22 antibodies potentially useful in the differential diagnosis, and analyzed the data with cluster analysis. Stain intensity was scored as none, weak, or strong. For CD99, tumors with membranous accentuation were independently categorized. Cluster analysis sorted five groups, with like tumors clustering together. Synovial sarcoma clustered into two groups: one cytokeratin and EMA positive (n = 11), the other mostly cytokeratin negative, EMA positive, bcl-2 positive and mostly CD56 positive (n = 9). Malignant peripheral nerve sheath tumor clustered into two groups: one S100 positive, with nestin and NGFR positivity in most (n = 10), the other mostly S100 negative, and variably but mostly weakly positive for nestin and NGFR (n = 11). Ewing sarcomas clustered into a single group driven by membranous CD99 staining. Thirteen cases failed to cluster (outliers), while three Ewing sarcomas clustered into groups of other tumor types. Paired antibodies for each tumor type determined by visual assessment of cluster analysis data and statistical calculations of specificity, sensitivity, and predictive values showed that EMA/CK7 for synovial sarcoma, nestin/S100 for malignant peripheral nerve sheath tumor, and membranous CD99/Fli-1 for Ewing sarcoma yielded high specificity and positive predictive values. Cluster analysis also highlighted aberrant staining reactions and diagnostic pitfalls in these tumors. Hierarchical cluster analysis is an effective method for analyzing high-volume immunohistochemical data.     

Renal primitive neuroectodermal tumors

Primitive neuroectodermal tumors exist as a part of the Ewing sarcoma/primitive neuroectodermal tumor family. These tumors most commonly arise in the chest wall and paraspinal regions; cases with a renal origin are rare entities, but have become increasingly reported in recent years. Although such cases occur across a wide age distribution, the average age for a patient with a renal primitive neuroectodermal tumor is the mid- to late 20s, with both males and females susceptible. Histologically, these tumors are characterized by pseudorosettes. Immunohistochemically, CD99 is an important diagnostic marker. Clinically, these are aggressive tumors, with an average 5-year disease-free survival rate of only 45% to 55%. Given that renal primitive neuroectodermal tumor bears many similarities to other renal tumors, it is important to review the histologic features, immunostaining profile, and genetic abnormalities that can be used for its correct diagnosis.     

Primary Ewing sarcoma/PNET of the kidney: fine-needle aspiration, histology, and dual color break apart FISH Assay

A 34-year-old previously healthy Hispanic man presented with lower back pain. CT scan revealed an 8-cm space-occupying lesion in the superior pole of the left kidney with numerous small lytic lesions in the skull, vertebrae, ribs, and pelvic bones. CT-guided fine-needle aspiration biopsy revealed a high-grade primitive small round cell tumor with the tumor cells being strongly positive for CD99 and vimentin. The patient subsequently underwent a left nephrectomy. Fluorescence in situ hybridization analysis using a DNA probe for the Ewing Sarcoma breakpoint region 1 (EWSR1) on chromosome 22g12 revealed a rearrangement of the EWSR1 locus. The diagnosis of primary Ewing sarcoma/primitive neuroectodermal tumor of the kidney was established.     

Adamantinoma‐like Ewing sarcoma of the parotid gland: Cytopathologic findings and differential diagnosis

Adamantinoma‐like Ewing sarcoma (AES) is a rare variant of Ewing sarcoma family of tumors (EFTs), primarily affecting bone and soft tissue. AES has mixed features of Ewing sarcoma (ES)/primitive neuroectodermal tumor (PNET) and adamantinoma with a complex immunoprofile and EWSR1 gene rearrangements. Herein, we report a 72‐year‐old male who presented with left parotid mass, right neck mass and thyroid nodules. Fine needle aspiration of the left parotid mass displayed nests of monotonous epithelioid cells with basaloid features in a background of small round blue cells and lymphocytes. AES can involve head and neck region and is characterized by groups of primitive small round blue cells admixed with groups of epithelioid cells with amphophilic cytoplasm and focal squamous differentiation. The proportion of these components can be variable, creating diagnostic challenges, particularly in unusual anatomic sites such as the parotid gland. However, when additional material is available, CD99 and/or FLI1 immunostains need to be included for diagnostic confirmation.     

Primary desmoplastic small round cell tumor of bone: report of a case with cytogenetic confirmation

We report a case of desmoplastic small round cell tumor occurring in the right ilium of a 13-year-old boy. Morphologically, the neoplasm consisted of small round cells of primitive appearance with a diffuse growth pattern replacing marrow space and eroding bone. Immunohistochemical staining was positive for vimentin, synapsin, CD99 (MIC2 protein), and FLI-1, prompting an initial diagnosis of Ewing sarcoma/primitive neuroectodermal tumor. However, a diagnosis of desmoplastic small round cell tumor was rendered after the detection by cytogenetic analysis of the reciprocal chromosomal translocation, t(11;22)(p13;q12), which is uniquely associated with this tumor. This is the first documented instance of desmoplastic small round cell tumor arising in bone.     

Intracranial peripheral primitive neuroectodermal tumors of the cavernous sinus: a diagnostic peculiarity

Peripheral primitive neuroectodermal tumors (pPNETs) are aggressive, poorly differentiated neoplasms that occur in children and young adults. These tumors are associated with a peak incidence in the second decade and a slight male preponderance. Recently, Ewing sarcoma and pPNET tumors have been proven to carry identical translocations, the most common being t(11;22)(q24;q12). Intracranial Ewing sarcoma/pPNETs have rarely been described in the literature. We studied a case of intracranial pPNET arising in the right cavernous sinus of a 46-year-old man. On imaging, the tumor had both sellar and suprasellar components and was centered within the right parasellar region. Histologically, the tumor was composed of intermediate to large cells with round to oval hyperchromatic nuclei with distinct nucleoli. The cells contained a moderate amount of slightly basophilic cytoplasm. The tumor was markedly fibrotic and had collagen bands surrounding both individual and groups of cells. A large immunohistochemical panel was positive only for CD99 and vimentin. Fluorescence in situ hybridization did not show translocations associated with Ewing sarcoma/pPNET. However, a small percentage of these tumors can be negative for this translocation. In these cases, histology and immunohistochemical techniques in the absence of an alternative diagnosis are the only tools available to establish the diagnosis.     

Ewing sarcoma/primitive neuroectodermal tumor of the kidney: a case report. Diagnosed by immunohistochemistry and molecular analysis

BACKGROUND: Ewing sarcoma/primitive neuroectodermal tumor (EWS/PNET) of the kidney is a rare and aggressive tumor. It has a rapid clinical progression with early metastasis and death. Few cases with documented t(11;22) have been reported in the literature. CASE PRESENTATION: We report a case of EWS/PNET of the kidney in a 26-year-old woman with widespread metastasis at initial presentation. The tumor cells showed strong expression for CD99 and FLI-1 monoclonal antibodies and polyclonal antibodies and were negative for WT1 and numerous other markers. The diagnosis was subsequently confirmed by demonstrating t(11;22)(q24;q12) using cytogenetic karyotyping and fluorescence in situ hybridization. CONCLUSIONS: Due to the different prognosis and management between EWS/PNET and other primary renal neoplasms with similar morphology, a histopathologic diagnosis with extreme accuracy should be made. Cytogenetic analysis is an important supportive tool to immunohistochemistry in making the final diagnosis.     

Primitive neuroectodermal tumor of the gallbladder

Ewing sarcoma/primitive neuroectodermal tumor (ES/ PNET) most commonly occurs in the soft tissues of the extremities and the paravertebral areas. To our knowledge, no case of PNET has been reported in the gallbladder to date. We report a case of PNET of the gallbladder occurring in a 53-year-old woman. Microscopically, the monotonous small round cells with a formation of Homer-Wright rosettes showed intense membranous positive immunoreactivity for MIC2/CD99, as well as for neuron-specific enolase and synaptophysin. Other small round cell tumors, such as lymphoma, rhabdomyosarcoma, or melanoma, were excluded in light of negative immunoreactivity for leukocyte common antigen, desmin, and S100. The diagnosis of PNET was rendered based on the characteristic morphology and immunohistochemical findings, despite an absence of chromosomal translocations, such as t(11; 22)(q24;q12) and t(21;22)(q22;q12).     

Expression of MYCN in pediatric synovial sarcoma.

Synovial sarcoma accounts for between 6 and 10% of childhood sarcomas and histological diagnosis can be challenging, even for experienced pathologists. Several other tumors enter the differential diagnosis, including malignant peripheral nerve sheath tumor, Ewing sarcoma/primitive neuroectodermal tumor and undifferentiated sarcoma. Several recent reports utilizing expression array techniques have documented expression of the MYCN oncogene in synovial sarcoma. In order to more fully investigate this finding, a series of 12 synovial sarcomas and 29 other sarcomas (four malignant peripheral nerve sheath tumors, 15 Ewing sarcoma/primitive neuroectodermal tumors, 10 undifferentiated sarcomas) were examined for MYCN expression and gene amplification. By RT-PCR, nine of 12 synovial sarcomas (75%) expressed MYCN. Five synovial sarcomas (42%) expressed MYCN at high levels. Of the other sarcomas, one malignant peripheral nerve sheath tumor (25%) and five Ewing sarcoma/primitive neuroectodermal tumors (33%) expressed MYCN at low levels, and all other cases were negative for MYCN. None of the synovial sarcomas had genomic amplification, suggesting that high MYCN expression levels resulted from epigenetic phenomena. Examination of selected downstream targets of MYCN in synovial sarcoma revealed expression of MCM7 (minichromosome maintenance protein 7) in all synovial sarcomas, and expression of nestin (n=10; 83%), ID2 (inhibitor of DNA binding protein 2) (n=6; 50%) and MRP1 (multidrug resistance protein 1) (n=1; 8%) in a subset of synovial sarcomas. Expression of downstream targets did not correlate with expression of MYCN. Neither MYCN nor expression of downstream targets significantly correlated with metastases at presentation, progression-free survival or overall survival in this small series. In summary, high levels of MYCN expression was useful for distinguishing synovial sarcoma from other childhood-spindled cell sarcomas with specificity and sensitivity of 100 and 42%, respectively, in this series. The clinical and biological significance of this finding deserves further study.     

A 15-year-old female with progressive myelopathy

March 2005. A 15-year-old female presented with urinary retention, inability to walk and low back pain. MRI disclosed an elongated epidural mass in the thoracic spine with cord compression and invasion into the surrounding bone and soft tissue. Cytologic preparation at intraoperative consultation disclosed a rather monotonous small tumor cells with hyperchromatic nuclei and vacuolated cytoplasm. These vacuoles were best visualized with DiffQuick stain. Pathologic studies revealed an Ewing sarcoma/peripheral primitive neuroectodermal tumor (EWS/pPNET) with typical features including periodic acid Schiff positive diastase sensitive cytoplasmic substance; strong membranous pattern of immunoreactivity for CD99, and a reciprocal translocation of t(11;22)(q24;q12) that was demonstrated by fluorescent in situ hybridization (FISH). The vacuolated cytoplasm was produced by glycogen as demonstrated by electron microscopy. Although primary vertebral EWS/pPNETs are uncommon, they should be considered in the differential diagnoses of extradural/epidural mass of the spine in young patients.     

Primary renal NUT carcinoma identified by next-generation sequencing: a case report and literature review

Background: NUT carcinoma is a rare aggressive squamous cell carcinoma subtype genetically characterized by NUTM1 rearrangements. NUT carcinoma can be easily misdiagnosed as an undifferentiated carcinoma or Ewing sarcoma due to its primitive differentiation. Case presentation: We report a case of renal-derived NUT carcinoma diagnosed as a malignant small round-cell tumor resembling Ewing sarcoma/primitive neuroectodermal tumor where the diagnosis was revised to NUT carcinoma with a characteristic NUTM1 rearrangement based on next-generation sequencing (NGS). The patient received a standard NUT carcinoma treatment after recurrence but died of first-line chemotherapy failure due to advanced neoplasm progression. Conclusion: Routine NUT immunohistochemistry staining, NGS, and/or fluorescent in situ hybridization for poorly differentiated carcinoma and sarcoma can help avoid misdiagnosis of NUT carcinoma-related tumors, allowing patients to benefit from bromodomain and extra-terminal motif inhibitor therapy.     

Lineage-specific identification of nonhematopoietic neoplasms by flow cytometry

To extend flow cytometry (FC) to the diagnosis of nonhematopoietic neoplasms, we have developed new flow cytometric assays to identify expression of cytokeratin, epithelial cell adhesion molecule (EpCAM)/epithelial glycoprotein-2, myogenin, and CD99. To validate these assays, we correlated the flow cytometric results with the histologic and immunohistochemical results on paraffin-embedded tissue in a series of 21 cases, including 17 carcinomas, 1 atypical carcinoid, 2 rhabdomyosarcomas, and 1 Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET). Six of 7 assayed carcinomas and the carcinoid were positive for cytoplasmic cytokeratin by the flow cytometric assay. EpCAM was expressed by 11 of 12 carcinomas that were assayed by FC. Both rhabdomyosarcomas expressed myogenin by FC, and the ES/PNET case expressed CD99. Interestingly, the blast-associated antigen CD90 was expressed uniformly on the ES/PNET case and on subsets of cells in the rhabdomyosarcoma and carcinoma cases. Potential applications of the flow cytometric assay to nonhematopoietic neoplasms will include evaluating samples with limited material, monitoring disease persistence and recurrence in patients with previous diagnoses, and making rapid diagnoses in urgent cases.     

微囊型脑膜瘤与脑膜尤文肉瘤/外周原始神经外胚层肿瘤的MRI鉴别诊断

目的:探讨微囊型脑膜瘤与脑膜尤文肉瘤/外周原始神经外胚层肿瘤（pPNET）的MRI征象。方法:回顾性分析经病理证实的14例微囊型脑膜瘤和10例脑膜尤文肉瘤/pPNET患者的临床、影像学及病理资料,结合相关文献分析其MRI差异。结果:微囊型脑膜和脑膜尤文肉瘤/pPNET患者MRI特征在肿瘤形态、T2信号、强化特征、骨侵犯及远处转移方面有统计学意义（P<0.05）;而在T1信号、硬膜尾征和瘤周水肿无统计学意义（P>0.05）。结论:微囊型脑膜瘤和脑膜尤文肉瘤/pPNET影像表现有差异,术前精准鉴别诊断有助于改善临床决策和预测预后。