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

Abdominal monophasic synovial sarcoma is a morphological and immunohistochemical mimic of gastrointestinal stromal tumour

AIMS

Synovial sarcomas may arise within retroperitoneal or pelvic tissues or, more rarely, within the luminal gastrointestinal tract. This case series aims to demonstrate how such primary abdominal synovial sarcomas may particularly mimic gastrointestinal stromal tumour (GIST) on both morphological and immunohistochemical grounds.

METHODS AND RESULTS

Four cases of primary abdominal synovial sarcoma were reviewed morphologically and with immunohistochemistry, fluorescence in-situ hybridization with an SS18 break-apart probe, and KIT/PDGFRA mutation analysis. The four patients comprised two males and two females, with a median age of 42 years (range: 17-59 years). Two synovial sarcomas arose within the stomach, one within the small-intestine mesentery, and the fourth within the retroperitoneum. All four tumours showed only a monophasic spindle cell component in the tissues available for review. All four tumours showed DOG1 immunopositivity, and three coexpressed CD117. Three tested cases did not show activating KIT or PDGFRA mutations, whereas all four cases showed chromosomal rearrangement of SS18.

CONCLUSIONS

A diagnosis of synovial sarcoma should be considered particularly if an abdominal spindle cell neoplasm shows a haemangiopericytomatous pattern and diffuse CD99 and CD56 immunopositivity. A confident distinction between abdominal synovial sarcoma and GIST requires KIT/PDGFRA mutation analyses and specific molecular testing for synovial sarcoma.

Atypical teratoid/rhabdoid tumor (AT/RT) arising from the acoustic nerve in a young adult: a case report and a review of literature

Atypical teratoid/rhabdoid tumors (AT/RTs) are rare, highly malignant central nervous system tumors that predominantly occur in young children. A 22-year-old woman presented with a 4-year history of relapsing tinnitus and gradual hearing loss. Neuroimaging revealed an enhanced intrinsic left internal auditory canal mass. The patient underwent radiotherapy treatment. Three years later, the tumor size continued to increase, as observed by imaging, and ultimately evolved into the left cerebellopontine angle. As a consequence, a total tumor resection was performed, and a pathological diagnosis of AT/RT was made. Aggressive radiotherapy and chemotherapy treatment continued; however, the tumor recurred within 11 months after the total tumor resection. The patient died within 4 months of the second operation. Histopathologically, the tumor contained characteristic rhabdoid cells with areas that resembled a classical primitive neuroectodermal tumor. Immunostaining showed loss of INI1 protein expression in tumor cells, and fluorescence in situ hybridization showed a hemizygous deletion of the hSNF5/INI1 gene region on 22q11.2. This is the first report of an AT/RT that arised from the acoustic nerve in a young adult. Despite manifold diagnostic and therapeutic advances, the prognosis of patients with AT/RT remains poor.

Synovial sarcoma: defining features and diagnostic evolution

Synovial sarcoma (SS) is a malignant mesenchymal neoplasm with variable epithelial differentiation, with a propensity to occur in young adults and which can arise at almost any site. It is generally viewed and treated as a high-grade sarcoma. As one of the first sarcomas to be defined by the presence of a specific chromosomal translocation leading to the production of the SS18-SSX fusion oncogene, it is perhaps the archetypal "translocation-associated sarcoma," and its translocation remains unique to this tumor type. Synovial sarcoma has a variety of morphologic patterns, but its chief forms are the classic biphasic pattern, of glandular or solid epithelial structures with monomorphic spindle cells and the monophasic pattern, of fascicles of spindle cells with only immunohistochemical or ultrastructural evidence of epithelial differentiation. However, there is significant morphologic heterogeneity and overlap with a variety of other neoplasms, which can cause diagnostic challenge, particularly as the immunoprofile is varied, SS18-SSX is not detected in 100% of SSs, and they may occur at unusual sites. Correct diagnosis is clinically important, due to the relative chemosensitivity of SS in relation to other sarcomas, for prognostication and because of the potential for treatment with specific targeted therapies in the near future. We review SS, with emphasis on the diagnostic spectrum, recent immunohistochemical and genetic findings, and the differential diagnosis.

How our practice of histopathology, especially tumour pathology has changed in the last two decades: reflections from a major referral center in Pakistan

Continued advances in the field of histo-pathology (and cyto-pathology) over the past two decades have resulted in dramatic changes in the manner in which these disciplines are now practiced. This is especially true in the setting of a large university hospital where the role of pathologists as clinicians (diagnosticians), undergraduate and postgraduate educators, and researchers has evolved considerably. The world around us has changed significantly during this period bringing about a considerable change in our lifestyles and the way we live. This is the world of the internet and the world-wide web, the world of Google and Wikipedia, of Youtube and Facebook where anyone can obtain any information one desires at the push of a button. The practice of histo (and cyto) pathology has also evolved in line with these changes. For those practicing this discipline in a poor, developing country these changes have been breathtaking. This is an attempt to document these changes as experienced by histo (and cyto) pathologists practicing in the biggest center for Histopathology in Pakistan, a developing country in South Asia with a large (180 million) and ever growing population. The Section of Histopathology, Department of Pathology and Microbiology at the Aga Khan University Hospital (AKUH) in Karachi, Pakistan's largest city has since its inception in the mid-1980s transformed the way histopathology is practiced in Pakistan by incorporating modern methods and rescuing histopathology in Pakistan from the primitive and outdated groove in which it was stuck for decades. It set histopathology in Pakistan firmly on the path of modernity and change which are essential for better patient management and care through accurate and complete diagnosis and more recently prognostic and predictive information as well.

Use of immunohistochemical staining and electron microscopy to aid in diagnosis of soft tissue sarcomas associated with the fetlock joint in two horses

Soft tissue sarcomas of the equine distal limb associated with joints, sheaths, or bursae have rarely been reported. Accurate diagnosis of these tumors is challenging in both human beings and veterinary species. Immunohistochemical staining and transmission electron microscopy have been used in human beings to reduce misdiagnosis. The current report describes 2 mature horses presenting with lameness and swelling associated with the dorsal aspect of the metacarpo(tarso)phalangeal joint. In both cases, surgical excision was performed with subsequent histological analysis of the masses to determine the tissue of origin. In both cases, immunohistochemical staining and transmission electron microscopy aided the definitive diagnosis of fibrosarcoma associated with the fetlock joints of 2 horses.

Neuregulin-1 overexpression and Trp53 haploinsufficiency cooperatively promote de novo malignant peripheral nerve sheath tumor pathogenesis

Malignant peripheral nerve sheath tumors (MPNSTs) are Schwann cell-derived malignancies that arise from plexiform neurofibromas in patients with mutation of the neurofibromin 1 (NF1) gene. We have shown that the growth factor neuregulin-1 (NRG1) also contributes to human neurofibroma and MPNST pathogenesis and that outbred C57BL/6J × SJL/J transgenic mice overexpressing NRG1 in Schwann cells (P0-GGFβ3 mice) recapitulate the process of neurofibroma-MPNST progression. However, it is unclear whether NRG1 acts predominantly within NF1-regulated signaling cascades or instead activates other essential cascades that cooperate with NF1 loss to promote tumorigenesis. We now report that tumorigenesis is suppressed in inbred P0-GGFβ3 mice on a C57BL/6J background. To determine whether NRG1 overexpression interacts with reduced Nf1 or Trp53 gene dosage to "unmask" tumorigenesis in these animals, we followed cohorts of inbred P0-GGFβ3;Nf1+/−, P0-GGFβ3;Trp53+/− and control (P0-GGFβ3, Nf1+/− and Trp53+/−) mice for 1 year. We found no reduction in survival or tumors in control and P0-GGFβ3;Nf1+/− mice. In contrast, P0-GGFβ3;Trp53+/− mice died on average at 226 days, with MPNSTs present in 95 % of these mice. MPNSTs in inbred P0-GGFβ3;Trp53+/− mice arose de novo from micro-MPNSTs that uniformly develop intraganglionically. These micro-MPNSTs are of lower grade (WHO grade II-III) than the major MPNSTs (WHO grade III-IV); array comparative genomic hybridization showed that lower grade MPNSTs also had fewer genomic abnormalities. Thus, P0-GGFβ3;Trp53+/− mice represent a novel model of low- to high-grade MPNST progression. We further conclude that NRG1 promotes peripheral nervous system neoplasia predominantly via its effects on the signaling cascades affected by Nf1 loss.

A patient with primary pericardial synovial sarcoma who presented with cardiac tamponade: a case report and review of the literature

A 36-year-old man presented with near-syncope. He was found to have massive pericardial effusion with a giant pericardial tumorous lesion. The pericardial effusion exhibited a bloody nature; however, neither malignant cells nor infectious organisms were detected. (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) showed an increased uptake of FDG in the pericardial tumor only. Although the tumor was not resectable, thoracotomy and tissue sampling were performed. A histological analysis showed CD99 positivity and SYT gene rearrangement, leading to a diagnosis of synovial sarcoma arising from the left lateral pericardial surface. The patient is now receiving chemotherapy.

Integrative DNA methylation and gene expression analysis in high-grade soft tissue sarcomas

Background

High-grade soft tissue sarcomas are a heterogeneous, complex group of aggressive malignant tumors showing mesenchymal differentiation. Recently, soft tissue sarcomas have increasingly been classified on the basis of underlying genetic alterations; however, the role of aberrant DNA methylation in these tumors is not well understood and, consequently, the usefulness of methylation-based classification is unclear.

Results

We used the Infinium HumanMethylation27 platform to profile DNA methylation in 80 primary, untreated high-grade soft tissue sarcomas, representing eight relevant subtypes, two non-neoplastic fat samples and 14 representative sarcoma cell lines. The primary samples were partitioned into seven stable clusters. A classification algorithm identified 216 CpG sites, mapping to 246 genes, showing different degrees of DNA methylation between these seven groups. The differences between the clusters were best represented by a set of eight CpG sites located in the genes SPEG, NNAT, FBLN2, PYROXD2, ZNF217, COL14A1, DMRT2 and CDKN2A. By integrating DNA methylation and mRNA expression data, we identified 27 genes showing negative and three genes showing positive correlation. Compared with non-neoplastic fat, NNAT showed DNA hypomethylation and inverse gene expression in myxoid liposarcomas, and DNA hypermethylation and inverse gene expression in dedifferentiated and pleomorphic liposarcomas. Recovery of NNAT in a hypermethylated myxoid liposarcoma cell line decreased cell migration and viability.

Conclusions

Our analysis represents the first comprehensive integration of DNA methylation and transcriptional data in primary high-grade soft tissue sarcomas. We propose novel biomarkers and genes relevant for pathogenesis, including NNAT as a potential tumor suppressor in myxoid liposarcomas.

Malignant Peripheral Nerve Sheath Tumors Masking as Ewing Sarcoma/Primitive Neuroectodermal Tumors

Malignant peripheral nerve tumors, a small subset of soft tissue sarcomas, provide a unique diagnostic challenge. Although they may arise from peripheral nerves or from cells associated with nerve sheaths, malignant peripheral nerve tumors often present with diverse immunohistochemical features similar to those of other tumors. These features make MPNSTs difficult to diagnose and classify. We present a case of a 26-year-old female presenting with a rapidly growing soft tissue mass. The mass was excised and immunohistological staining suggested a Ewing’s sarcoma/Primitive neuroectodermal tumor. Confirmational studies did not confirm this diagnosis and upon further review, the diagnosis was changed to a malignant peripheral nerve sheath tumor. We reviewed this case in the setting of the reported literature concerning MPNSTs with focus on the epidemiologic, diagnostic, and immunohistologic features that distinguish this tumor from other similar malignancies.

Molecular Pathology of Sarcoma

The rapid growth of tissue-based molecular pathology has changed the practice of the surgical pathologist signing out soft tissue tumors. This information is presented in a practical and succinct manner focusing on clinically validated findings that have diagnostic or therapeutic relevance. The approach is morphologically based and focuses on differential diagnoses and clinical scenarios. Molecular techniques can be an invaluable ancillary tool.

Malignant peripheral nerve sheath tumors: differentiation patterns and immunohistochemical features - a mini-review and our new findings

Malignant peripheral nerve sheath tumors (MPNST) represent a group of highly heterogeneous human malignancies often with multiple histological origins, divergent differentiation patterns, and diverse immunohistochemical presentations. The differential diagnosis of MPNST from other spindle cell neoplasms poses great challenges for pathologists. This report provides a mini-review of these unique features associated with MPNST and also presents the first cases of MPNST with six differentiation patterns.

Downstream and intermediate interactions of synovial sarcoma-associated fusion oncoproteins and their implication for targeted therapy

Synovial sarcoma (SS), an aggressive type of soft tissue tumor, occurs mostly in adolescents and young adults. The origin and molecular mechanism of the development of SS remain only partially known. Over 90% of SS cases are characterized by the t(X;18)(p11.2;q11.2) translocation, which results mainly in the formation of SS18-SSX1 or SS18-SSX2 fusion genes. In recent years, several reports describing direct and indirect interactions of SS18-SSX1/SSX2 oncoproteins have been published. These reports suggest that the fusion proteins particularly affect the cell growth, cell proliferation, TP53 pathway, and chromatin remodeling mechanisms, contributing to SS oncogenesis. Additional research efforts are required to fully explore the protein-protein interactions of SS18-SSX oncoproteins and the pathways that are regulated by these partnerships for the development of effective targeted therapy.

Concise review: transmissible animal tumors as models of the cancer stem-cell process

Tasmanian devil facial tumor disease (DFTD) and canine transmissible venereal tumor (CTVT) are highly unusual cancers capable of being transmitted between animals as an allograft. The concept that these tumors represent a cancer stem-cell process has never been formally evaluated. For each, evidence of self-renewal is found in the natural history of these tumors in the wild, tumor initiation in recipient animals, and serial transplantation studies. Additional data for stem-cell-specific genes and markers in DFTD also exist. Although both tumor types manifest as undifferentiated cancers, immunocytohistochemistry supports a histiocytic phenotype for CTVT and a neural crest origin, possibly a Schwann-cell phenotype, for DFTD. In these data, differential expression of lineage markers is seen which may suggest some capacity for differentiation toward a heterogeneous variety of cell types. It is proposed that DFTD and CTVT may represent and may serve as models of the cancer stem-cell process, but formal investigation is required to clarify this. Appreciation of any such role may act as a stimulus to ongoing research in the pathology of DFTD and CTVT, including further characterization of their origin and phenotype and possible therapeutic approaches. Additionally, they may provide valuable models for future studies of their analogous human cancers, including any putative CSC component.

Inhibin-α and synaptophysin immunoreactivity in synovial sarcoma with granular cell features

We recognized immunoreactivity for the α subset of inhibin and synaptophysin in synovial sarcomas with granular cell features. Histologic findings of 90 cases of synovial sarcoma were reviewed. Two (2.2%) of the 90 cases had granular cell features, showing sheet or nested proliferation of characteristic epithelioid cells with abundant eosinophilic and granular cytoplasm, in addition to the typical spindle cell component. The 2 cases were both female (aged 86 and 76 years). The tumors were located in the foot and the retroperitoneum and measured 3.5 and 14 cm in maximum diameter. Reverse transcriptase polymerase chain reaction analysis revealed SS18-SSX1 transcripts in both cases. SS18 gene rearrangement was detected in granular cells as well as spindle cells by chromogenic in situ hybridization. Immunohistochemistry found the granular cells to be positive for inhibin-α in both cases and for synaptophysin in 1 case, whereas spindle cells were not. Thirty-six cases (20 monophasic fibrous, 11 biphasic, and 5 poorly differentiated synovial sarcomas) were additionally examined for comparison; they showed no immunoreactivity for inhibin-α or synaptophysin. This is the first report of immunoreactivity for inhibin-α and synaptophysin in synovial sarcoma. These immunohistochemical findings might be characteristic of synovial sarcomas with granular cell features.

Immunohistochemical expression and cluster analysis of mesenchymal and neural stem cell-associated proteins in pediatric soft tissue sarcomas

Pediatric undifferentiated soft tissue sarcomas (USTSs) are a group of malignancies composed predominantly of primitive round cell sarcomas, the histogenesis of which is uncertain. Thus, diagnosis and therapy remain a challenge. The aims of the current study were to determine whether differential expression of stem cell-associated proteins could be used to aid in determining the histogenesis of pediatric USTSs and to determine whether pediatric USTSs expressed a unique panel of stem cell-associated proteins to aid diagnosis. Tumors included 28 Ewing sarcoma/primitive neuroectodermal tumors (ESs), 22 embryonal rhabdomyosarcomas (ERMSs), 8 alveolar rhabdomyosarcomas (ARMSs), 5 synovial sarcomas (SSs), 5 malignant peripheral nerve sheath tumors (MPNSTs), and 13 USTSs. Stem cell antibodies included 3 mesenchymal stem cell markers (CD44, CD105, and CD166) and 5 neural stem cell markers (CD15, CD29, CD56, CD133, and nestin). Sections were scored followed by statistical analysis, clustering analysis, and visualizations using Partek Genomic Suite Software. The Euclidean clustering divided the tumors into 2 major groups. ESs and USTSs formed the majority of the 1st group, whereas ERMSs, ARMSs, MPNSTs, and SSs formed the 2nd group. Reduced expression of CD56 was strongly associated with the ES/USTS cluster (P < 0.0001). ESs and USTSs were further separated by CD166 staining, wherein increased expression was associated with ES (P < 0.0001). The 2nd group included the majority of other sarcomas, with no consistent separation between subtypes. The current study demonstrates the usefulness of applying stem cell markers to pediatric sarcomas and indicates that USTSs and ESs are closely related and may share a common histogenesis.

Primary pulmonary synovial cell sarcoma: radiological findings and management

Primary pulmonary synovial cell sarcoma is a rare tumor without specific symptoms, signs, or radiological features. The role of functional imaging has not yet been evaluated, and diagnosis is usually made on histopathological examination. Positron-emission computed tomography findings and surgical resection in a 22-year-old man and a 40-year-old woman are described.

A novel case of rhabdoid colon carcinoma associated with a positive CpG island methylator phenotype and BRAF mutation

Colon carcinoma with rhabdoid characteristics is a rare, malignant tumor whose molecular alterations have not been clarified yet. We report a novel case of a colon adenocarcinoma with rhabdoid features in a 71-year-old woman, localized to the right colon and associated with local lymph node and liver metastasis. The patient died within 8 months from surgery despite target chemotherapy. The tumor was enriched in cells with a typical rhabdoid-type morphology displaying a marked and diffuse vimentin staining. Cells were also positive for epidermal growth factor receptor (EGFR), p53, Ki67, and β-catenin and negative for cytokeratin 20/cytokeratin 7, E-cadherin, and CDX2. Remarkably, the promoter regions of 4 of 5 specific genes that define the so-called "CpG island methylator phenotype," including mutL homolog 1 (MLH1), were methylated. Consistently, microsatellite instability was detected. A BRAF V600E mutation and no KRAS mutations were identified. Finally, 4 tumor suppressor gene promoters CDH1, CDKN1B, CDKN1C, and MGMT were not methylated. This is the first case of a colorectal carcinoma with rhabdoid features, "CpG island methylator phenotype," high microsatellite instability associated with a BRAF mutation, and patient poorer outcome.

Immunohistochemistry in diagnosis of soft tissue tumours

Immunohistochemistry in soft tissue tumours, and especially sarcomas, is used to identify differentiation in the neoplastic cells. In some cases, specific antigens are expressed; however, an initial panel of antibodies is often required in order to establish the broad lineage, with a subsequent, more focused, panel to allow classification. Immunohistochemical evaluation must be employed with the clinical picture, the morphology, and, when necessary, other ancillary techniques such as molecular genetics and cytogenetics. Whereas some diagnoses are evident on morphology, many soft tissue neoplasms are seen microscopically as spindle cell, epithelioid cell, small round cell or pleomorphic tumours that need to be further characterized. This article reviews selected applications of immunohistochemistry in the diagnosis of each of the principal morphological groups, concentrating on areas of most use in daily practice.

Spindle cell carcinoma of the nasal cavity

We report an extremely rare case of spindle cell carcinoma of the sinonasal cavity. A 75-year-old man was admitted to our hospital because of right nasal obstruction. Nasal endoscopy showed a polypoid tumor measuring 3 × 3 cm at the nasal septum in the right nasal cavity, and an excisional biopsy was performed. Computed tomography (CT) demonstrated the nasal tumor extended to the maxillary sinus. Histologically, the tumor consisted of malignant spindle cells with hyperchromatic nuclei. Mitotic figures and necrosis were recognized. In some areas, edematous changes were recognized. No apparent differentiation was noted. The tumor cells were free of keratinization and intercellular bridge formations; therefore, there were no squamous cell components. Immunohistochemically, the tumor cells were positive for pancytokeratin, cytokeratin (CK)5/6, CK18, CK19, high molecular weight CK, p63, and vimentin. The tumor cells were negative for epithelial membrane antigen, CK7, CK14, p53 protein, S100 protein, HMB45, chromogranin, synaptophysin, CD34, CD56, glial fibrillary acidic protein, neuron-specific enolase, neurofilaments, α-smooth muscle actin, neuroblastoma, myoglobin, carcinoembryonic antigen (CEA), carbohydrate antigen (CA)19-9, CD3, CD20, CD30, CD45RO, and CD45. A pathological diagnosis of spindle cell carcinoma of sinonasal lesion was made. The patient underwent resection of right maxilla followed by chemotherapy and radiation and was alive without metastasis 5 years after initial presentation.

Initial testing of the replication competent Seneca Valley virus (NTX-010) by the pediatric preclinical testing program

BACKGROUND

Seneca Valley virus (NTX-010) is a non-recombinant, replication competent RNA virus that is undergoing phase 1 clinical trials in adults for tumors with neuroendocrine characteristics. Here we have evaluated the antitumor activity of NTX-010 administered systemically.

PROCEDURES

In vitro NTX-010 was tested against 23 cell lines exposed for 96 hr at 1 x 10(-4) to 10(4) viral particles (vp)/cell. In vivo NTX-010 was administered intravenously once at 3 x 10(12) vp/kg. Three measures of antitumor activity were used: (1) an objective response measure modeled after the clinical setting; (2) a treated to control (T/C) tumor volume measure; and (3) a time to event (fourfold increase in tumor volume for solid tumor models), measure based on the median event-free survival (EFS) of treated and control animals for each xenograft.

RESULTS

In vitro NTX-010 demonstrated a marked cytotoxic effect in a subset of the cell lines from the neuroblastoma, Ewing sarcoma, and rhabdomyosarcoma panels. In vivo the most consistent activity was observed for the rhabdomyosarcoma and the neuroblastoma panels, with all four of the alveolar rhabdomyosarcoma xenografts and four of five neuroblastoma xenografts achieving CR or maintained CR. Objective responses were also observed in the rhabdoid tumor, Wilms tumor, and glioblastoma panels.

CONCLUSIONS

NTX-010 demonstrated a high level of activity both in vitro and in vivo. Further analysis of existing testing and molecular characterization data may help define the biological characteristics of cancer cells that are associated with response to NTX-010.

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.

Cluster analysis of immunohistochemical markers in leiomyosarcoma delineates specific anatomic and gender subgroups

BACKGROUND

Leiomyosarcoma (LMS) can be categorized into uterine, retroperitoneal, nonretroperitoneal soft tissue, cutaneous, visceral, and osseous anatomic subtypes. The differential expression of smooth muscle markers, estrogen receptor (ER), progesterone receptor (PR), and Wilms tumor-1 protein (WT1) by anatomic subtype and gender was explored.

METHODS

A total of 78 LMS comprised of 30 uterine and 48 nonuterine tumors were studied. Nonuterine tumors were comprised of 17 soft tissue, 16 retroperitoneal, 7 cutaneous, 5 visceral, and 3 osseous subtypes. Immunohistochemical staining intensity on tissue microarray slides was scored as 0, 1+, or 2+, and cluster analysis was performed on the data.

RESULTS

Smooth muscle actin was the most sensitive antibody (95%), followed by muscle-specific actin (91%), calponin (88%), desmin (73%), caldesmon (66%), and myosin (64%). Caldesmon and myosin were usually coexpressed, and were highest in retroperitoneal tumors (94%). There was no discernable correlation noted between histologic differentiation and smooth muscle marker expression. ER was much more common in women, with the highest frequencies noted in female retroperitoneal (86%) and uterine (63%) tumors. Nuclear WT1 was expressed in 11% of all tumors, and was limited to ER-positive uterine and female retroperitoneal tumors. Cluster analysis segregated 4 groups, most notably 1 driven by ER and PR, with the vast majority being uterine and female retroperitoneal tumors.

CONCLUSIONS

Smooth muscle markers demonstrated variable sensitivities in LMS, with a tendency for anatomic subtypes to segregate based on expression patterns of these markers. ER defined a subgroup of uterine and female retroperitoneal tumors, and WT1 was limited to such tumors, suggesting a common line of differentiation as well as potential therapeutic targets.

Expression of adhesion molecules and ligands for activating and costimulatory receptors involved in cell-mediated cytotoxicity in a large panel of human melanoma cell lines

Knowledge of the interactions between MHC-unrestricted cytotoxic effector cells and solid tumour cells is essential for introducing more effective NK cell-based immunotherapy protocols into clinical practise. Here, to begin to obtain an overview of the possible universe of molecules that could be involved in the interactions between immune effector cells and melanoma, we analyse the surface expression of adhesion and costimulatory molecules and of ligands for NK-activating receptors on a large panel of cell lines from the "European Searchable Tumour Cell Line and Data Bank" (ESTDAB, http://www.ebi.ac.uk/ipd/estdab/ ) and discuss their potential role in the immune response against this tumour. We show that most melanoma cell lines express not only adhesion molecules that are likely to favour their interaction with cells of the immune system, but also their interaction with endothelial cells potentially increasing their invasiveness and metastatic capacity. A high percentage of melanoma cell lines also express ligands for the NK-activating receptor NKG2D; whereas, the majority express MICA/B molecules, ULBP expression, however, was rarely found. In addition to these molecules, we also found that CD155 (poliovirus receptor, PVR) is expressed by the majority of melanoma cell lines, whereas CD112 (Nectin-2) expression was rare. These molecules are DNAM-1 ligands, a costimulatory molecule involved in NK cell-mediated cytotoxicity and cytokine production that also mediates costimulatory signals for triggering naïve T cell differentiation. The phenotypical characterisation of adhesion molecules and ligands for receptors involved in cell cytotoxicity on a large series of melanoma cell lines will contribute to the identification of markers useful for the development of new immunotherapy strategies.

Molecular abnormalities in Ewing's sarcoma

Ewing's sarcoma is one of the few solid tumors for which the underlying molecular genetic abnormality has been described: rearrangement of the EWS gene on chromosome 22q12 with an ETS gene family member. These translocations define the Ewing's sarcoma family of tumors (ESFT) and provide a valuable tool for their accurate and unequivocal diagnosis. They also represent ideal targets for the development of tumor-specific therapeutics. Although secondary abnormalities occur in over 80% of primary ESFT the clinical utility of these is currently unclear. However, abnormalities in genes that regulate the G(1)/S checkpoint are frequently described and may be important in predicting outcome and response. Increased understanding of the molecular events that arise in ESFT and their role in the development and maintenance of the malignant phenotype will inform the improved stratification of patients for therapy and identify targets and pathways for the design of more effective cancer therapeutics.

Pulmonary Carcinoid Tumor Masquerading as a Synovial Sarcoma

A rare case of pulmonary carcinoid tumor exhibiting morphologically as a monophasic synovial sarcoma is reported. The patient is a 37-year-old man who presented with shortness of breath for several weeks. The chest computed tomographic scan showed a 3.5 cm pulmonary mass in the left lower lobe.The lesion was an oval, tan nodule displaying features of monophasic synovial sarcoma. Immunohistochemical studies were performed and included a carcinoid tumor as a main differential diagnosis. Reverse transcriptase polymerase chain reaction and fluorescence in situ hybridization studies were negative for a molecular evidence of synovial sarcoma. This case further emphasizes the capacity of pulmonary carcinoid tumor cells to show various morphologic expressions even toward a mesenchymal differentiation mimicking a synovial sarcoma.

Nestin expression in osteosarcomas and derivation of nestin/CD133 positive osteosarcoma cell lines

Background

Nestin was originally identified as a class VI intermediate filament protein that is expressed in stem cells and progenitor cells in the mammalian CNS during development. This protein is replaced in the adult organism by other intermediate filament proteins; however, nestin may be re-expressed under certain pathological conditions such as ischemia, inflammation, brain injury, and neoplastic transformation. Nestin has been detected in many kinds of tumors, especially in tumors derived from the CNS. Co-expression of nestin and the CD133 surface molecule is considered to be a marker for cancer stem cells in neurogenic tumors. Our work was aimed at a detailed study of nestin expression in osteosarcomas and osteosarcoma-derived cell lines.

Methods

Using immunodetection methods, we examined nestin in tumor tissue samples from 18 patients with osteosarcomas. We also successfully established permanent cell lines from the tumor tissue of 4 patients and immunodetection of nestin and CD133 was performed on these cell lines.

Results

Nestin-positive tumor cells were immunohistochemically detected in all of the examined osteosarcomas, but the proportion of these cells that were positively stained as well as the intensity of staining varied. Nestin-positive cells were rarely observed in 2 tumor samples, and the remaining 16 tumor samples showed various nestin expression patterns ranging from very sporadic occurrence to an overwhelming proportion of cells with strong positive staining. Three of the established osteosarcoma cell lines were demonstrated to be nestin-positive, and only one cell line showed no expression of nestin; this finding corresponds with the rare occurrence of nestin-positive cells in the respective tumor sample. Moreover, three of these osteosarcoma cell lines were undoubtedly proven to be Nes+/CD133+.

Conclusion

Our results represent the first evidence of nestin expression in osteosarcomas and suggest the possible occurrence of cells with a stem-like phenotype in these tumors.

Is nonsmall cell type high-grade neuroendocrine carcinoma of the tubular gastrointestinal tract a distinct disease entity?

Although small cell carcinoma of the gastrointestinal (GI) tract is well-recognized, nonsmall cell type high-grade neuroendocrine carcinoma (HGNEC) of this site remains undefined. At the current time, neither the World Health Organization nor American Joint Committee on Cancer includes this condition in the histologic classifications, and consequently it is being diagnosed and treated inconsistently. In this study, we aimed at delineating the histologic and immunophenotypical spectrum of HGNECs of the GI tract with emphasis on histologic subtypes. Guided primarily by the World Health Organization/International Association for the Study of Lung Cancer criteria for pulmonary neuroendocrine tumors, we were able to classify 87 high-grade GI tract tumors that initially carried a diagnosis of either poorly differentiated carcinoma with or without any neuroendocrine characteristics, small cell carcinoma, or combined adenocarcinoma-neuroendocrine carcinoma into the following 4 categories. The first was small cell carcinoma (n=23), which had features typical of pulmonary small cell carcinoma, although the cells tended to have a more round nuclear contour. The second was large cell neuroendocrine carcinoma (n=31), which had a morphology similar to its pulmonary counterpart and showed positive immunoreactivity for either chromogranin (71%) or synaptophysin (94%) or both. The third was mixed neuroendocrine carcinoma (n=11), which had intermediate histologic features (eg, cells with an increased nuclear/cytoplasmic ratio but with apparent nucleoli), and positive immunoreactivity for at least 1 neuroendocrine marker. The fourth was poorly differentiated adenocarcinoma (n=17). In addition, 5 of the 87 tumors showed either nonsmall cell type neuroendocrine morphology (n=3) or immunohistochemical reactivity for neuroendocrine markers (n=2), but not both. Further analysis showed that most HGNECs arising in the squamous lined parts (esophagus and anal canal) were small cell type (78%), whereas most involving the glandular mucosa were large cell (53%) or mixed (82%) type; associated adenocarcinomas were more frequent in large cell (61%) or mixed (36%) type than in small cell type (26%); and focal intracytoplasmic mucin was seen only in large cell or mixed type. As a group, the 2-year disease-specific survival for patients with HGNEC was 25.4% (median follow-up time, 11.3 mo). No significant survival difference was observed among the different histologic subtypes. In conclusion, our study demonstrates the existence of both small cell and nonsmall cell types of HGNEC in the GI tract, and provides a detailed illustration of their morphologic spectrum. There are differences in certain pathologic features between small cell and nonsmall cell types, whereas the differences between the subtypes of nonsmall cell category (large cell versus mixed) are less distinct. Given the current uncertainty as to whether large cell neuroendocrine carcinoma is as chemosensitive as small cell carcinoma even in the lung, our data provide further evidence in favor of a dichotomous classification scheme (small cell vs. nonsmall cell) for HGNEC of the GI tract. Separation of nonsmall cell type into large cell and mixed subtypes may not be necessary. These tumors are clinically aggressive. Prospective studies using defined diagnostic criteria are needed to determine their biologic characteristics and optimal management.