Mediastinal Germ Cell Tumors: A Review and Update on Pathologic, Clinical, and Molecular Features

Mediastinal germ cell tumors (MGCTs) are the most common extragonadal germ cell tumors (GCTs) and most often arise in the anterior mediastinum with a male predilection. MGCTs also have a predilection for patients with Klinefelter syndrome and possibly other genetic conditions. MGCTs, as GCTs at other extragonadal sites, are thought to arise from germ cells improperly retained during migration along the midline during embryogenesis. Similar to their counterparts in the testes, MGCTs are classified into seminomatous and nonseminomatous GCTs. Seminomatous MGCT represents pure seminoma, whereas nonseminomatous MGCTs encompass pure yolk sac tumors, embryonal carcinoma, choriocarcinoma, mature or immature teratoma, and mixed GCTs with any combination of GCT types, including seminoma. Somatic-type or hematologic malignancies can also occur in association with a primary MGCT. MGCTs share molecular findings with GCTs at other sites, most commonly the presence of chromosome 12p gains and isochromosome i(12p). Treatment includes neoadjuvant chemotherapy followed by surgical resection of residual tumor, with the exception of benign teratomas, which require only surgical resection without chemotherapy. In this review, we highlight and provide an update on pathologic, clinical, and molecular features of MGCTs. Immunohistochemical profiles of each tumor type, as well as differential diagnostic considerations, are discussed.

Altered FDG Biodistribution in Subcutaneous White Fat on PET/CT Following l-Asparaginase Chemotherapy

ABSTRACT

A 13-year-old boy with mediastinal T-cell lymphoblastic lymphoma demonstrated an altered biodistribution with diffuse activity in subcutaneous white adipose tissue and decreased visceral activity on interim posttreatment FDG PET/CT. This altered biodistribution was attributed to administration of the chemotherapeutic enzyme l-asparaginase 3 hours preceding the PET/CT, altering adipocytes amino acid and glucose metabolism. Treatment response assessment was adversely affected by the altered biodistribution, emphasizing the importance of maximizing the time between chemotherapy and PET/CT during successive oncologic treatment cycles. Because adipocytes protect leukemic cells in culture from l-asparaginase, we hypothesize that white adipose tissue-altered biodistribution may be related to l-asparaginase resistance.

The utility of CD83, fascin and CD23 in the differential diagnosis of primary mediastinal large B-cell lymphoma versus classic Hodgkin lymphoma

Primary mediastinal large B-cell lymphoma (PMBL) and classic Hodgkin lymphoma (CHL) are the most common large cell lymphomas arising in the mediastinum and are thought to be closely related histogenetically. Although the distinction between PMBL and CHL is usually straightforward, in some cases it is challenging and rarely these neoplasms have intermediate features and qualify for the diagnosis of mediastinal gray zone lymphoma (GZL). CD83 and fascin are markers of CHL and CD23 is a marker of PMBL. In this study we assess the utility of this combination of these immunohistochemical markers to distinguish CHL from PMBL. We retrospectively collected cases of PMBL, CHL and GZL from three centers. Tissue sections were stained with CD83, fascin and CD23. CD83 was expressed in the neoplastic cells of 100% of CHL (22/22), 93% of GZL (16/18) and 41% of PMBL (9/22). Similarly, fascin was positive in the neoplastic cells of 100% of CHL (22/22), 86% of GZL (18/21) and 32% of PMBL (7/22). CD23 was positive in 95% of PMBL (21/22), 67% of GZL (12/18) and 9% of CHL (2/22). CD83 and fascin are sensitive markers for CHL but not specific whereas CD23 is sensitive for PMBL and uncommon in CHL. The GZL cases in this study had an intermediate immunophenotype, but the results were closer to CHL than PMBL. A large panel of immunohistochemical studies is recommended to distinguish CHL from PMBL entities and we suggest that CD83, fascin and CD23 add value to panels designed for this differential diagnosis.

Biology and therapy of primary mediastinal B-cell lymphoma: current status and future directions

Primary mediastinal B-cell lymphoma (PMBCL) is a distinct disease closely related to classical nodular sclerosing Hodgkin lymphoma. Conventional diagnostic paradigms utilising clinical, morphological and immunophenotypical features can be challenging due to overlapping features with other B-cell lymphomas. Reliable diagnostic and prognostic biomarkers that are applicable to the conventional diagnostic laboratory are largely lacking. Nuclear factor kappa B (NF-κB) and Janus kinase/signal transducers and activators of transcription (JAK-STAT) signalling pathways are characteristically dysregulated in PMBCL and implicated in several aspects of disease pathogenesis, and the latter pathway in host immune evasion. The tumour microenvironment is manipulated by PMBCL tumours to avoid T-cell mediated destruction via strategies that include loss of tumour cell antigenicity, T-cell exhaustion and activation of suppressive T-regulatory cells. R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone) and DA-EPOCH-R (dose-adjusted etoposide, prednisolone, vincristine, cyclophosphamide, doxorubicin, rituximab) are the most common first-line immunochemotherapy regimens. End of treatment positron emission tomography scans are the recommended imaging modality and are being evaluated to stratify patients for radiotherapy. Relapsed/refractory disease has a relatively poor outcome despite salvage immunochemotherapy and subsequent autologous stem cell transplantation. Novel therapies are therefore being developed for treatment-resistant disease, targeting aberrant cellular signalling and immune evasion.

Metabolic heterogeneity on baseline 18FDG-PET/CT scan is a predictor of outcome in primary mediastinal B-cell lymphoma

An important unmet need in the management of primary mediastinal B-cell lymphoma (PMBCL) is to identify the patients for whom first-line therapy will fail to intervene before the lymphoma becomes refractory. High heterogeneity of intratumoral 18F-fluorodeoxyglucose (18FDG) uptake distribution on positron emission tomography/computed tomography (PET/CT) scans has been suggested as a possible marker of chemoresistance in solid tumors. In the present study, we investigated the prognostic value of metabolic heterogeneity (MH) in 103 patients with PMBCL prospectively enrolled in the International Extranodal Lymphoma Study Group (IELSG) 26 study, aimed at clarifying the role of PET in this lymphoma subtype. MH was estimated using the area under curve of cumulative standardized uptake value-volume histogram (AUC-CSH) method. Progression-free survival at 5 years was 94% vs 73% in low- and high-MH groups, respectively (P = .0001). In a Cox model of progression-free survival including dichotomized MH, metabolic tumor volume, total lesion glycolysis (TLG), international prognostic index, and tumor bulk (mediastinal mass > 10 cm), as well as age as a continuous variable, only TLG (P < .001) and MH (P < .001) retained statistical significance. Using these 2 features to construct a simple prognostic model resulted in early and accurate (positive predictive value, 89%; negative predictive value, ≥90%) identification of patients at high risk for progression at a point that would allow the use of risk-adapted treatments. This may provide an important opportunity for the design of future trials aimed at helping the minority of patients who harbor chemorefractory PMBCL. The study is registered at ClinicalTrials.gov as NCT00944567.

STAT6 is a cargo of exportin 1: Biological relevance in primary mediastinal B-cell lymphoma

Primary mediastinal B-cell lymphoma (PMBL) is a distinct B-cell lymphoma subtype with unique clinicopathological and molecular features. PMBL cells are characterised by several genetic abnormalities that conduct to the constitutive activation of the Janus kinase 2/signal transducer and activator of transcription 6 (JAK2/STAT6) signalling pathway. Among recurrent genetic changes in PMBL, we previously reported that the XPO1 gene encoding exportin 1 that controls the nuclear export of cargo proteins and RNAs, is mutated (p.E571K) in about 25% of PMBL cases. We therefore hypothesized that STAT6 could be a cargo of XPO1 and that STAT6 cytoplasm/nucleus shuttle could be altered in a subset of PMBL cells. Using immunocytochemistry techniques as well as the proximity ligation assay, we showed that STAT6 bound XPO1 in PBML cell lines and in HEK-293 cells genetically engineered to produce STAT6. Moreover, XPO1-mediated export of STAT6 occurs in cells expressing either a wild-type or the E571K mutated XPO1 protein.

Positron Emission Tomography/Computed Tomography Assessment After Immunochemotherapy and Irradiation Using the Lugano Classification Criteria in the IELSG-26 Study of Primary Mediastinal B-Cell Lymphoma

PURPOSE

To assess the predictive value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) for disease recurrence after immunochemotherapy (R-CHT) and mediastinal irradiation (RT), using the recently published criteria of the Lugano classification to predict outcomes for patients with primary mediastinal large B-cell lymphoma.

METHODS AND MATERIALS

Among 125 patients prospectively enrolled in the IELSG-26 study, 88 were eligible for central review of PET/CT scans after completion of RT. Responses were evaluated using the 5-point Deauville scale at the end of induction R-CHT and after consolidation RT. According to the Lugano classification, a complete metabolic response (CMR) was defined by a Deauville score (DS) ≤3.

RESULTS

The CMR (DS1, -2, or -3) rate increased from 74% (65 patients) after R-CHT to 89% (78 patients) after consolidation RT. Among the 10 patients (11%) with persistently positive scans, the residual uptake after RT was slightly higher than the liver uptake in 6 patients (DS4; 7%) and markedly higher in 4 patients (DS5; 4%): these patients had a significantly poorer 5-year progression-free survival and overall survival. At a median follow-up of 60 months (range, 35-107 months), no patients with a CMR after RT have relapsed. Among the 10 patients who did not reach a CMR, 3 of the 4 patients (positive predictive value, 75%) with DS5 after RT had subsequent disease progression (within the RT volume in all cases) and died. All patients with DS4 had good outcomes without recurrence.

CONCLUSIONS

All the patients obtaining a CMR defined as DS ≤3 remained progression-free at 5 years, confirming the excellent negative predictive value of the Lugano classification criteria in primary mediastinal large B-cell lymphoma patients. The few patients with DS4 also had an excellent outcome, suggesting that they do not necessarily require additional therapy, because the residual 18F-fluorodeoxyglucose uptake may not reflect persistent lymphoma.

Pleuromediastinal Epithelial-Myoepithelial Carcinomas: A Clinicopathologic and Immunohistochemical Study of Two Cases

OBJECTIVES

Two cases of epithelial-myoepithelial carcinoma are presented, one arising in the pleura and the other in the anterior mediastinum. The cases represent a unique distribution of these tumors within the thoracic cavity.

METHODS

Both patients were men aged 25 and 68 years, respectively, who had chest pain and dyspnea. Imaging revealed an anterior mediastinal mass in one patient and a pleural-based tumor in the other. Neither patient had any history of malignancy, and physical examination did not disclose any tumor elsewhere.

RESULTS

Initial biopsy specimens were inconclusive, and final diagnosis was deferred to surgical resection performed via median sternotomy and thoracotomy, respectively. Histologically, the lesions were characterized by epithelial and myoepithelial elements distributed as discrete tubules or duct-like structures or sheets of neoplastic cells. Immunohistochemistry showed positive staining for cytokeratin and epithelial membrane antigen in the epithelial component, while S100 protein and smooth muscle actin were expressed in the myoepithelial elements. Follow-up showed that both patients were alive 6 and 12 months after surgery, respectively.

CONCLUSIONS

These cases highlight the ubiquitous distribution of salivary gland-type tumors in the thoracic cavity. These tumors should be included in the differential diagnosis of thoracic neoplasms also in locations other than the lung.

Primary pleuropulmonary and mediastinal synovial sarcoma: a clinicopathologic and molecular study of 26 genetically confirmed cases in the largest institution of southwest China

BACKGROUND

Primary pleuropulmonary and mediastinal synovial sarcomas (PPMSSs) are extremely rare. The authors present the largest series in an Asian population.

METHODS

Between 2000 and 2015, 26 genetically confirmed PPMSSs were included. The clinicopathologic features of all of the cases were reviewed. Immunohistochemical staining was carried out using the following antibodies: TLE1, cytokeratin (AE1/AE3), EMA, CD99, Bcl-2, CK7, CD34, S-100 protein, and Ki-67. The chromosomal translocation t(X;18)(p11.2;q11.2) was detected by fluorescence in situ hybridization (FISH) and reverse transcription polymerase chain reaction (RT-PCR). We compared the clinical, pathologic, immunohistochemical, and molecular features of this series with that of the previous series and soft tissue synovial sarcomas.

RESULTS

This series included 17 males and nine females. The median age was 36.5 years (range, 16-72 years). The tumors involved the lung (76.9 %), pleura (15.4 %), and mediastinum (7.7 %). The median tumor size was 6 cm (range 2.3 ~ 24 cm). The majority of the tumors were well-circumscribed. The tumors were classified as monophasic (84.6 %), biphasic (3.8 %), and poorly differentiated (11.5 %) types. The tumors were graded as French Federation of Cancer Centers (FNCLCC) grade 2 (62.5 %) and FNCLCC 3 (37.5 %). Diffuse immunostaining for TLE1, BCL-2, and CD99 was identified in 91.7, 95.7, and 56.0 % of the tumors, respectively. Focal positivity was seen with EMA (84.6 %), CK7 (55.6 %), cytokeratin (AE1/AE3) (68.0 %), CD34 (5.0 %), and S-100 protein (21.7 %). A high Ki-67 index (≥10 %) was observed in 91.3 % of the tumors. The fusion transcripts included SS18-SSX1 (15/22, 68.2 %), SS18-SSX2 including variants (6/22, 27.3 %), and SS18-SSX4 (1/22, 4.5 %) fusions. The remaining four cases showed positivity for SS18 rearrangement by FISH. Surgical excision of tumors or lobectomy were performed in 20 patients, and seven of the patients underwent adjuvant therapy. Clinical follow-up was available in 73.1 % cases, with a median follow-up of 12.0 months. The median survival time was 14.5 months. Tumor resection (p = 0.024) and no residual tumor (p = 0.004) were associated with an improved overall survival time.

CONCLUSIONS

PPMSS is a highly aggressive neoplasm. Extensive surgical resection of the tumor and more effective adjuvant therapy should be advocated. PPMSS must be differentiated from similar diseases.

[Epithelioid hemangioendothelioma: a clinicopathologic analysis of 13 cases]

OBJECTIVE

To investigate the clinicopathologic characteristics of epithelioid hemangioendothelioma (EHE).

METHODS

Thirteen cases of EHE were analyzed by gross examination, light microscopy and immunohistochemical staining.

RESULTS

The patients included 6 males and 7 females. The age of patients ranged from 11 to 74 years (mean = 43 years). The tumors were located in soft tissue, liver, lung, mediastinum, sacrum, and pleura. The tumor cells were epithelioid, spindled or polygonal-shaped and exhibited cord-like or small nest growth pattern. Some tumor cells formed cytoplasmic vacuoles, which contained erythrocytes. The tumor cells showed abundant eosinophilic cytoplasm. The stroma varied from highly myxoid to hyaline. In 3 cases, the tumors contained areas with significant atypia, brisk mitotic activity and necrosis. Immunohistochemical study showed that the tumor cells were positive for CD31, ERG, FLI-1, CD34, factor VIII and CKpan to different extents. Follow-up information was available in 10 patients with duration ranging from 8 to 65 months. Seven patients were alive and three died.

CONCLUSIONS

EHE is easily a rare maligant vascular tumor,occurs in many organs other than soft tissue.EHE is misdiagnosed as carcinoma for its significant epithelioid morphology. Recognizing its clinicopathologic characteristics and combined application of specific vascular endothelial immunohistochemical markers are important to avoid confusion with other lesions.

NUT Midline Carcinoma: Morphoproteomic Characterization with Genomic and Therapeutic Correlates

NUT midline carcinoma is a rare entity arising primarily in the midline of teenagers and young adults. Genomically, it is associated with a translocation involving a nuclear protein in testis (NUT) gene with other genes, most commonly, the BRD4 gene. The resultant is a partial or near total block in differentiation of tumor cells into mature squamous elements. Such tumors are resistant to conventional therapy with a reported mean survival at less than 1 year. In this study, we investigated two cases with genomic confirmation as NUT midline carcinoma by morphoproteomic analysis using immunohistochemical antibodies. Our results showed overexpression, largely in the undifferentiated cells of the tumors of: 1) Stemness marker, SRY (sex determining region Y)-box 2 (Sox2); 2) Constitutive activation of the mTORC2 pathway with expression of total insulin-like growth factor-1 receptor (IGF-1R[Tyr1165/1166]), and nuclear p-mTOR (Ser 2448) and p-Akt (Ser 473); and 3) c-Myc, silent mating type information regulation 2 homolog 1 (Sirt1) and histone methyltransferase enhancer of Zeste, Drosophila, homolog 2 (EZH2) as molecular impediments to differentiation. These data were analyzed through the use of QIAGEN's Ingenuity(®) Pathway Analysis (IPA(®), QIAGEN Redwood City, www.qiagen.com/ingenuity). The results established the interconnection of these pathways and molecules, and identified several pharmacogenomic agents--melatonin, metformin, vorinostat, curcumin, and sulforaphane--that have the potential to remove the block in differentiation and lead to the establishment of a more benign form of NUT midline carcinoma.

A case of anterior mediastinum paraganglioma presented with pericardial effusion two years before symptoms of catecholamine excess: first case report in Thailand

Pheochromocytoma (PCC) and paraganglioma (PGL) are uncommon tumors. Clinical manifestations are mass effect or hormone secretion. The initial manifestation with pericardial effusion is rare. The author presented a case of anterior mediastinum paraganglioma presenting with pericardial effusion two years before symptoms of catecholamine excess. This is the first case reported in Thailand. A 34 year-old female patient presented with dyspnea. There was pericardial effusion from echocardiography was diagnosed with no definite causes of pericardial effusion. After treatment with ibuprofen, pericardial effusion was absolutely resolved from repeated echocardiography. Two years later she had headache and hypertension. Chest X-ray, there was an anterior mediastinal mass. Her 24 hours urine metanephrine was very high. By imaging, an anterior mediastinal mass was observed from CT chest without adrenal mass from CT abdomen. The result of metaiodobenzylguanidine (MIBG) scan was compatible with paraganglioma. Symptoms of headache and hypertension disappeared after surgical removal of the mass. Pericardial effusion may be the first manifestation of paraganglioma especially if the patient had hypertension or could not find the etiology. Thus, pericardial effusion should be investigated for paraganglioma. Due to long term follow-up, this indolent growing tumor may respond to NSAIDs or regress spontaneously.

Activating mutations affecting the NF-kappa B pathway and EZH2-mediated epigenetic regulation are rare events in primary mediastinal large B-cell lymphoma

BACKGROUND

Primary mediastinal large B-cell lymphoma (PMBL) is a distinct subtype of diffuse large B-cell lymphoma (DLBCL) frequently observed in young patients. High-dose immunochemotherapy constitutes the current therapeutic gold-standard, despite significant toxicity and serious late effects. Several hotspots harboring oncogenic gain-of-function mutations were recently shown to pose vital hallmarks in activated B-cell like (ABC-) (CD79B, CARD11 and MYD88) and germinal center like (GCB-) DLBCL (EZH2), respectively. Several promising targeted-therapy approaches, derived from these findings, are currently under development.

MATERIALS AND METHODS

We thoroughly characterized a cohort of 25 untreated patients with de novo PMBL by immunohistochemical and cytogenetic means and assessed the prevalence of activating mutations affecting EZH2, CD79B and CARD11 utilizing a polymerase chain reaction (PCR)-based capillary sequencing approach. Moreover, the MYD88 p. L265P status was assessed by employing a pyrosequencing approach.

RESULTS

PMBLs included in this study did not harbor any of the reported hotspot mutations activating the nuclear factor (NF)-kappa B signaling cascade or the EZH2-mediated epigenetic deregulation of gene expression. Immunohistochemical characterization revealed an ABC phenotype in 44% (n=11) of cases.

CONCLUSION

We report that genetic alterations of these genes are rare events in PMBL unlike other subtypes of DLBCL. Our findings suggest that a substantial subset of PMBL patients may benefit from treatment approaches targeting BCR-mediated activation of NF-kappa B.

Ectopic acromegaly due to growth hormone releasing hormone

Acromegaly secondary to extra-pituitary tumors secreting growth hormone releasing hormone (GHRH) is rarely encountered. We review the literature on ectopic acromegaly and present the index report of ectopic acromegaly secondary to GHRH secretion from a mediastinal paraganglioma. Clinical and pathological manifestations and therapeutic management of 99 patients with ectopic acromegaly are reviewed. Acromegaly secondary to ectopic GHRH secretion is usually caused by a neuroendocrine tumor in the lung and pancreas. We report an additional cause of ectopic acromegaly from a mediastinal paraganglioma. Diagnostic criteria of ectopic GHRH syndrome include biochemical and pathologic tumoral confirmation of GHRH secretion and expression. Management of ectopic acromegaly consists of surgical resection of the primary tumor and biochemical normalization, with possible adjuvant use of somatostatin analogs. The review demonstrates that there are several tumor types, including paragangliomas which may secrete GHRH, leading to acromegaly. Clinical and laboratory manifestations of the syndrome and challenges in diagnosis and management of these rarely encountered patients require early diagnosis and appropriate treatment to prevent long-term morbidity and mortality with ectopic acromegaly.

[Epithelioid hemangioendothelioma of the mediastinum]

The paper describes a rare case of mediastinal epithelioid hemangioendothelioma characterized by a population of fusiform cells, metaplastic osteogenesis, and aggressive behavior. A 5.5x4-cm encapsulated mass was found in the anterior mediastinum of a 19-year-old female patient. A bone density tumor was sealed with lung tissue and it occluded the lumen of the left subclavian vein. Microscopically, the tumor was composed of foci of the so-called "blister cells" typical of epithelioid hemangioendothelioma, anastomosing chains of epithelioid cells in the microhyaline stroma, diffusely located bone trabeculae, and hemorrhagic stroma. Fusiform cells were present in considerable quantities. A moderate cellular and nuclear polymorphism occurred when mitotic figures were absent. Tumor cells expressed Flil, vimentin, CD31, and CD34. Multiple metastases were detected in the liver and lung. They had the similar morphology.

Mediastinal ganglioneuroma with perineural cell differentiation. Report of a case

An unusual case of ganglioneuroma with perineural cell differentiation is presented. The tumor was removed from the mediastinum in a 34-year-old male patient. Histologically, it contained neuroid bundles of bland spindle cells, scattered ganglion cells, and some foci of adipocytic metaplasia. Immunohistochemically, the tumor showed expected expressions of S100 protein, neurofilament protein and calretinin. In addition, many spindle cells were positive for perineural cell markers EMA, claudin-1, and GLUT-1. These cells were often arranged in an organoid fashion around the schwannoid bundles. This case indicates that the cells of ganglioneuroma can mature simultaneously towards both Schwann cell and perineural cell phenotypes.

[Clinicopathologic and immunohistochemical study of 23 cases of mesenchymal chondrosarcoma]

OBJECTIVE

To study the clinicopathologic and immunohistochemical features of mesenchymal chondrosarcoma.

METHODS

The clinical and histologic features of 23 cases of mesenchymal chondrosarcoma were analyzed. Immunohistochemical study was also performed in 14 of the cases.

RESULTS

The age of patients ranged from 12 to 47 years. Fourteen of them occurred in males. Thirteen cases involved the bony skeleton and 5 cases affected the soft tissue. The patients presented with pain and/or swelling. Histologically, the tumor consisted of a mixture of undifferentiated small round cells and hyaline cartilage. Transition between the two components was demonstrated and growth plate-like cartilage was observed. Immunohistochemical study showed that the small round cells were positive for Sox9 (14/14), CD99 (12/14), vimentin (6/14), CD56 (4/14), CD57 (4/14), neuron-specific enolase (3/14) and desmin(1/14). They were negative for Coll-II, S-100 protein, epithelial membrane antigen, pan-cytokeratin, synaptophysin, chromogranin A, CD34 and c-erbB2.

CONCLUSIONS

Mesenchymal chondrosarcoma is a rare malignant tumor. Thorough histologic examination, when coupled with immunohistochemical findings, is helpful in arriving at a correct diagnosis.

T-cell acute lymphoblastic leukemia associated with complex karyotype and SET-NUP214 rearrangement: a case study and review of the literature

SET-NUP214 rearrangements have been rarely reported in T-cell acute lymphoblastic leukemia (T-ALL), acute undifferentiated leukemia, and acute myeloid leukemia, and most documented cases have been associated with normal karyotypes in conventional cytogenetic analyses. Here, we describe a novel case of T-ALL associated with a mediastinal mass and a SET-NUP214 rearrangement, which was masked by a complex karyotype at the time of initial diagnosis. Using multiplex reverse transcriptase-polymerase chain reaction analysis, we detected a cryptic SET-NUP214 rearrangement in our patient. As only 11 cases (including the present study) of T-ALL with SET-NUP214 rearrangement have been reported, the clinical features and treatment outcomes have not been fully determined. Further studies are necessary to evaluate the incidence of SET-NUP214 rearrangement in T-ALL patients and the treatment responses as well as prognosis of these patients.

Management of anaplastic thyroid carcinoma spread over the trachea with mediastinal extension

INTRODUCTION

We report a case of treatment of anaplastic thyroid carcinoma spread over the trachea with mediastinal extension.

METHODS

Case report and review of the world literature concerning the treatment of anaplastic thyroid carcinoma are presented.

DISCUSSION

The role of surgery in treatment of anaplastic carcinoma remains controversial. Our case we underlined two questions: the appropriateness of the surgery options with extra-thyroid spread and the better surgery approach to anaplastic thyroid carcinoma interesting the mediastinum controlling the great vessels of the neck. Even if curative resection cannot be achieved, surgical resection can immediately reduce the tumor bulk to facilitate the efficacy of post-operative radiotherapy and/or chemotherapy and to achieve a good local control to avoid the need of a subsequent palliative tracheostomy. Tumor upper mediastinal involvement made mandatory to open the sternum in order to allow a more complete resection of the macroscopic mass. The mini-sternotomy represents a valuable alternative that allows reduction in surgical trauma increasing patient's comfort.

CONCLUSION

The complete resection of the tumor mass without scarifying vital structures can lead to some prolonged survival. Even if complete resection cannot be achieved, surgical resection can immediately reduce the tumour bulk and achieve good local control of the disease to avoid the palliative tracheotomy.

Report of a case of epithelioid hemangioendothelioma of the anterior mediastinum metastatic to pleura

We present a case of epithelioid hemangioendothelioma metastatic to pleura, in a 69-year-old woman with chest pain. This distinctive vascular neoplasm can arise in various organs, most commonly in middle-aged women. It is characterized by slow growth, and, microscopically, by epithelioid tumor cells in appearance. Epithelioid hemangioendothelioma should be distinguished mainly from primary or metastatic carcinomas and angiosarcoma. Definitive diagnosis often requires immunohistochemistry. Its clinical course is unpredictable, although survival rates are better than for angiosarcoma.

Ganglioneuroma presenting as a paraesophageal mass lesion diagnosed by endoscopic ultrasound-guided fine needle aspiration cytology: a case report

BACKGROUND

Endoscopic ultrasound-guided fine needle aspiration is a well-established modality in detection and diagnosis of mediastinal lesions. Ganglioneuroma is a benign, rare, soft tissue neoplasm arising from sympathetic ganglion cells, and complete surgical resection is considered to be curative. Ganglioneuroma in a surgical specimen is a straightforward diagnosis; however, due to the infrequent occurrence of this entity, diagnosis by fine needle aspiration is more challenging.

CASE

A case of paraesophageal ganglioneuroma was diagnosed by endoscopic ultrasound-guided fine needle aspiration. A 75-year-old man with a history of adenocarcinoma of the lung was noted to have a mediastinal mass on chest computed tomography. Upper endosonography identified a 40x17-mm mass extrinsic to the thoracic esophagus. An endoscopic ultrasound-guided fine needle aspiration of the mass revealed intermingled fragments of spindle cells and ganglion cells admixed within a fibromyxoid stroma. Immunohistochemistry showed that both the spindle and ganglion cell components were positive for S-100 protein and negative for pancytokeratin. This immunohistochemical profile established both the neurogenic origin of the spindle and ganglion cells.

CONCLUSION

Our case represents 1 of the few reported cases of ganglioneuroma diagnosed by fine needle aspiration cytology and the second case diagnosed under endoscopic ultrasound guidance.

Immature teratoma of the mediastinum arising in ectopic thyroid tissue: a case report

BACKGROUND

Papillary carcinoma can arise from ectopic thyroid tissue, but teratoma have not been described. Differentiation into thyroid follicles does not occur in mediastinal teratomas.

CASE

A case of upper mediastinal immature teratoma occurred in an 18-day-old male newborn. The histologic examination revealed the presence of a discontinuous rim of compressed thyroid follicles on the outer aspect of the tumor capsule. This finding is consistent with the origin of the teratoma in ectopic thyroid tissue, and it has not been previously described in the literature. The patient was free of disease after 22 months, in accordance with the benign behavior of immature teratoma in infancy.

CONCLUSION

Ectopic thyroid tissue can undergo the same pathologic changes as the thyroid gland, including the rare occurrence of teratoma.

[Primary soft tissue sarcomas of mediastinum: experience in 22 cases from a single institution]

OBJECTIVE

To assess the presentation, imaging features, and prognostic factors of primary soft tissue sarcoma of mediastinum.

METHODS

The clinical data of 22 patients with primary soft tissue sarcoma of mediastinum, 12 males and 10 females, aged 46 (28-69), hospitalized over 27 years were retrospectively reviewed, focusing on the clinical presentations, preoperative diagnosis, imaging features, immunohistochemical studies, treatment, and survival.

RESULTS

Chest pain, dyspnea, cough, and shoulder pain were the most common complaints. Imaging findings showed large lobulated mass. The overall 5-year survival rate was 62. 8%. The 5-year survival rate of the patients with tumors larger than 10 cm was 65.6%, significantly higher than that of the patients with tumors smaller than 10 cm (38.8% , P = 0. 019). The long-term survival rate of the patients who received complete resection was 84 months , longer, though not significantly, than that of the patients who received incomplete resection (8 months, P = 0.059). The 5-year survival rate of the patients with lesions at high grade and stage III were 38.2% and 38.2% respectively, both lower, though not significantly, than those of lesions at low grade and stage I (60% and 60% respectively, both P =0.317). The 5-year survival rate of the patients who received surgery only was 8 months, shorter, though not significantly, than that of the patients who received surgery plus adjuvant therapy (12 months, P = 0.204).

CONCLUSION

Tumor size and character of resection are important prognostic factors for primary soft tissue sarcoma of mediastinum.

[Clinicopathologic and prognostic study of pediatric immature teratoma]

OBJECTIVE

To study the clinicopathologic features and biologic behavior of pediatric immature teratoma.

METHODS

The clinical data, pathologic features, immunohistochemical findings (for cyclin D1, P27 and Ki-67) and follow-up information of 39 cases of pediatric immature teratoma were analyzed.

RESULTS

Amongst the 39 cases studied, 12 arose in the sacrococcygeal region, 12 in testis, 5 in retroperitoneum, 4 in ovary, 4 in abdomen and 2 in mediastinum. Histologically, 16 cases were of grade 1, 8 cases of grade 2 and 15 cases of grade 3. Seven of the cases contained foci of yolk sac tumor. Immature neuroepithelial features used in histologic grading included the presence of primitive neural tubules, immature rosettes, undifferentiated neuroblastoma cells and primitive neuroectodermal structures. Immunohistochemical study showed that cyclin D1 was positive in 3 cases of grade 1 tumors, 4 cases of grade 2 tumors and 9 cases of grade 3 tumors. The positivity rates for p27 were 8, 3 and 6 cases respectively, while those for Ki-67 were 3, 4 and 13 cases respectively. Follow-up data were available in 30 cases. Three of them, including 2 cases with histologic grade 3 (with or without yolk sac tumor component), recurred after operation.

CONCLUSIONS

The expression of cyclin D1 and Ki-67 is a useful adjunct in histologic grading. On the other hand, p27 overexpression shows little correlation with tumor grade. The prognosis of immature teratoma in children is different from that in adults. Sacrococcygeal immature teratoma occurring in patients younger than 1 year old and with low histologic grade do not require postoperative chemotherapy if the tumor is completely excised. Similarly, for testicular immature teratoma occurring in patients below 1 year of age, regardless of tumor grading, need no adjunctive therapy. On the other hand, ovarian immature teratoma with high histologic grade requires postoperative chemotherapy, regardless of age of the patients. The presence of microscopic foci of yolk sac tumor is a useful predictor of recurrence in pediatric immature teratoma.

Decreased Tc-99m Sestamibi Uptake in a Sternal Brown Tumor Indicating Response to Anti Metabolic Therapy for Secondary Hyperparathyroidism

Brown tumors are rare but serious complications of renal osteodystrophy, and can be treated by parathyroidectomy or by pharmacological treatment of hyperparathyroidism. In addition to parathyroid lesions such as adenoma, hyperplasia, and carcinoma, brown tumors have been detected effectively by using dual phase Tc-99m sestamibi and Tl-201 chloride. We describe an unusual case of brown tumor at the manibrium sterni which shows marked increased Tc-99m sestamibi uptake on the initial scan, with decreasing tracer activity on follow-up scan indicating a response to antimetabolic therapy.

Target Sequence Accessibility Limits Activation-Induced Cytidine Deaminase Activity in Primary Mediastinal B-Cell Lymphoma

Activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) in activated B lymphocytes and is potentially implicated in genomic instability of B-cell malignancies. For unknown reasons, B-cell neoplasms often lack SHM and CSR in spite of high AID expression. Here, we show that primary mediastinal B-cell lymphoma (PMBL), an immunoglobulin (Ig)-negative lymphoma that possesses hypermutated, class-switched Ig genes, expresses high levels of AID with an intact primary structure but does not do CSR in 14 of 16 cases analyzed. Absence of CSR coincided with low Ig germ-line transcription, whereas high level germ-line transcription was observed only in those two cases with active CSR. Interleukin-4/CD40L costimulation induced CSR and a marked up-regulation of germ-line transcription in the PMBL-derived cell line MedB-1. In the PMBL cell line Karpas 1106P, CSR was not inducible and germ-line transcription remained low on stimulation. However, Karpas 1106P, but not MedB-1, had ongoing SHM of the Ig gene and BCL6. These genes were transcribed in Karpas 1106P, whereas transcription was undetectable or low in MedB-1 cells. Thus, accessibility of the target sequences seems to be a major limiting factor for AID-dependent somatic gene diversification in PMBL.

Primary pulmonary and mediastinal synovial sarcoma: a clinicopathologic study of 60 cases and comparison with five prior series

Primary pulmonary and mediastinal synovial sarcoma is rare and poses a diagnostic challenge particularly when unusual histological features are present. We present 60 cases of primary pulmonary and mediastinal synovial sarcoma (29 male and 27 female subjects; mean age, 42 years) and compare our results with five prior series to better define unusual histological features. Clinically, patients with mediastinal synovial sarcoma were younger with a male gender bias. Radiologically, tumors were well delineated with distinctive magnetic resonance imaging features and little vascular enhancement. In all, 21/46 patients died of disease within 5 years. Histologically, all tumors had dense cellularity, interlacing fascicles, hyalinized stroma, and mast cell influx. Hemangiopericytoma-like vasculature (48/60), focal myxoid change (30/60), and entrapped pneumocytes (23/60) were seen. Calcification was not prevalent (10/60). Unusual histological features included Verocay body-like formations (7/60), vague rosettes (6/60), well-formed papillary structures (3/60), adenomatoid change (3/60), and rhabdoid morphology (2/60). Immunohistochemistry demonstrated expression of pancytokeratin (39/58), epithelial membrane antigen (29/53), cytokeratin 7 (26/40), cytokeratin 5/6 (5/7), calretinin (15/23), CD99 (19/23), bcl-2 (24/24), CD56 (11/11), S-100 (9/51), and smooth muscle actin (8/32). In total, 92% (36/39) of primary pulmonary and mediastinal synovial sarcomas studied were positive for t(x;18). In conclusion, our study confirms the clinical, histological, immunohistochemical, and molecular data from previous large series of primary pulmonary and mediastinal synovial sarcoma. Compared with soft tissue synovial sarcoma, primary pulmonary and mediastinal synovial sarcoma has less calcification, less obvious mast cell influx, and less radiologic vascularity, but similar magnetic resonance imaging features, percentage of poorly differentiated tumors, and number of t(x;18)-positive tumors. Awareness of focal unusual histology can prevent misdiagnosis particularly in t(x;18)-negative tumors.

Primary central nervous system histiocytic sarcoma with relapse to mediastinum: a case report and review of the literature

Histiocytic sarcoma is a rare, malignant neoplasm of the lymphohematopoietic system that usually occurs in the skin, lymph node, and intestinal tract. Here we describe a unique case of primary central nervous system histiocytic sarcoma that initially showed an indolent clinical course following local resection and radiotherapy. However, relapse of disease within the mediastinum was noted 3 1/2 years later. Biopsies of the initial brain lesion and subsequent mediastinal recurrence each revealed an identical, diffuse proliferation of histiocytes with expression of CD45, CD68, and CD163 but not pan-cytokeratin, epithelial membrane antigen, CD3, CD15, CD20, CD30, CD43, CD79a, CD138, myeloperoxidase, ALK-1, PAX-5, CAM 5.2, S100, CD1a, or glial fibrillary acidic protein. In the literature, central nervous system histiocytic sarcoma portends a poor prognosis with median survival of 4.5 months. To our knowledge, this case represents the first case of "low-grade" primary central nervous system histiocytic sarcoma with relatively indolent clinical course. A thorough discussion of the differential diagnosis of histiocytic sarcoma and a review of primary central nervous system histiocytic sarcoma are also presented.

[Unusual expression and molecular mechanisms of E-cadherin, beta-catenin in correlation with clinicopathologic parameters in neuroblastoma]

OBJECTIVE

To study the expression of E-cadherin and beta-catenin in neuroblastomas of various degrees of differentiation, and to investigate their molecular mechanisms in correlation with clinicopathologic parameters.

METHODS

Immunohistochemistry EnVision method was used to detect E-cadherin and beta-catenin expression in 90 paraffin-embedded tissue samples of neuroblastomas. The methylation status of CpG islands of E-cadherin promoter was investigated by MSP in 7 fresh tissue and 24 paraffin-embedded tissue samples. The mutation status of exon 3 of beta-catenin gene was studied by PCR in 7 fresh tissue samples. Statistical analysis of the data was performed by SPSS software.

RESULTS

E-cadherin and beta-catenin were abnormally expressed in neuroblastomas in general. The expression of beta-catenin in well-differentiated neuroblastoms was markedly higher (47/70, 67.1%) than that of the poorly differentiated tumors (8/20, 40.0%). There was a markedly decreased expression of both genes in tumors with lymph node metastasis than those without. Demethylation was seen in some regions of the promoter of E-cadherin in 31 cases of nuroblatomas. PCR of the exon 3 of beta-catenin followed by DNA sequencing demonstrated rearrangements and mutations in 7 cases, including 2 cases harboring identical point mutation at gene position 27184, leading to a T-->A alteration.

CONCLUSIONS

The abnormal over-expression of E-cadherin in neuroblastomas is independent of the methylation status of their promoter sequences. The abnormal expression of beta-catenin may be related to mutational changes at exon 3 of the gene.

Ovarian serous carcinoma presenting with mediastinal lymphadenopathy 20 months before the intraabdominal mass: Role of immunohistochemistry

INTRODUCTION

Metastatic involvement of the mediastinal lymph nodes is an extremely uncommon finding in epithelial ovarian cancers.

CASE REPORT

A 63-year-old woman was admitted to hospital for dyspnoea due to an anterior mediastinal mass. The surgical biopsy showed a 6-cm metastatic lymph node with a papillary pattern, scattered psammomas and immunoreactivity for WT1, Cytokeratin 7, EMA and negative for E-cadherin, GCFDP-15, Thyroglobulin, Cytokeratin 20, Cytokeratin 5/6, CEA, Vimentin, Calretinin, TTF1. After 20 months a follow-up CT identified an ovarian mass with the same histological pattern and immunoreactivity of the mediastinal nodule.

RESULTS

Immunohistochemistry, especially WT1, is useful in assessing the ovarian origin of an unusual metastasis particularly if it is the first presentation of the disease.

Primary mediastinal anaplastic alk-1-positive large-cell lymphoma of T/NK-cell type expressing CD20

We describe an unusual case of ALK-1-positive primary mediastinal lymphoma with the morphology of an anaplastic large-cell lymphoma (ALCL) of T/NK cell type but expressing CD20. This tumour had T/NK morphology and immunophenotype, as demonstrated by its expression of CD30, EMA, ALK-1, CD7 and TiA-1 and the lack of expression of B-cell markers other than CD20. The significance of such a co-expression of a B cell-associated antigen in a case of ALCL of T/NK cell type is discussed.

A case of T/null anaplastic large cell lymphoma arising in lung

Anaplastic large cell lymphoma (ALCL) is a rare non-Hodgkin, T-cell lymphoma, representing only 2-3% of all lymphoid neoplasm's in adults according to World Health Organization (WHO). CD30 antigen-positive, large neoplastic cells characterize ALCL. We present here a 46-year-old male with pulmonary ALCL previously diagnosed with Hodgkin disease. Microscopically, atypical bi-and multinucleated cells with frequent mitoses were present. The neoplastic cells were large and had clear cytoplasm, large vesicular nuclei, and prominent nucleoli. Immunophenotypic analysis revealed LCA, vimentin and CD30 positivity. ALK immunostaining was negative. Immunohistochemical profile was consistent with ALK negative ALCL. The progression of Hodgkin lymphoma to aggressive non-Hodgkin lymphoma (ALCL in this case) is well known entity. After the diagnosis was established, our patient immediately had been referred to the Department of Hematology in order to get appropriate chemotherapy, necessary in such cases.

Expression of TRAF1 and Nuclear c-Rel Distinguishes Primary Mediastinal Large Cell Lymphoma From Other Types of Diffuse Large B-cell Lymphoma

Primary mediastinal large B-cell lymphoma (PMLBCL) is a recently identified subtype of diffuse large B-cell lymphoma (DLBCL) that is difficult to distinguish from other types of DLBCL on the basis of histologic features alone. We recently identified a molecular signature of PMLBCL that is distinct from other forms of DLBCL but shares features with classical Hodgkin lymphoma. This signature includes activation of the nuclear factor kappaB (NFkappaB) signaling pathway, which in part, acts through nuclear translocation of c-Rel containing NFkappaB transcriptional complexes, and subsequent expression of NFkappaB target genes such as tumor necrosis factor receptor-associated factor-1 (TRAF1). Using standard immunohistochemical techniques, we examined 251 large B-cell lymphomas (78 cases of PMLBCL and 173 cases of other types of DLBCL) to determine whether the expression patterns of c-Rel and TRAF1 could reliably distinguish between PMLBCL and other types of DLBCL. Robust nuclear c-Rel was present in 31 of 48 (65%) cases of PMLBCL and 28 of 160 (18%) cases of DLBCL. In addition, cytoplasmic TRAF1 expression was seen in 48 of 78 (62%) cases of PMLBCL, but only 20 of 173 (12%) cases of DLBCL. Finally, the combined expression of nuclear c-Rel and TRAF1 was seen in 24 of 45 cases (53%) of PMLBCL, but in only 3 of 156 cases (2%) of other types of DLBCL. Thus, the combined nuclear localization of c-Rel and the cellular expression of TRAF1 is a highly specific (specificity=98%) means to distinguish PMLBCL from DLBCL that is readily applicable to routine surgical pathology practice.

Gains ofREL in primary mediastinal B-cell lymphoma coincide with nuclear accumulation of REL protein

Gains or amplifications of the REL locus are frequently seen in primary mediastinal B-cell lymphoma (PMBL). In classical Hodgkin's lymphoma, genomic overrepresentation of REL correlated with nuclear REL protein accumulation. To investigate the correlation between REL gene copies and its RNA and protein expression in PMBL, we analyzed genomic, transcriptional, and protein levels in 20 PMBLs and the PMBL derived cell lines MedB-1 and Karpas1106P. We found gains/amplifications in 75% of the PMBLs by fluorescence in situ hybridization (FISH) and genomic REL overrepresentation in the PMBL lines. Three of the five PMBLs with amplifications displayed elevated REL transcripts, while only 3/10 PMBLs with gains showed increased REL transcripts by real-time PCR. One PMBL without gains displayed increased REL transcription. REL protein expression exhibited a variable pattern across the PMBLs except for a single case that was completely negative by immunohistochemistry despite having gained REL. Although transcript levels were generally low and nuclear REL staining was weak in the lymphoma cell lines, these nevertheless exhibited high NF-kappaB activation. By fluorescence immunophenotyping and interphase cytogenetics as a tool for investigation of neoplasms, genomic gains/amplifications of REL significantly correlated with nuclear REL expression (P < 0.05). In conclusion, the frequent genomic overrepresentation of REL in PMBL does not necessarily trigger an increased transcription/translation of REL. However, combined genomic and protein analysis revealed a significant association of gained REL and nuclear REL accumulation at the single cell level.

Interferon alpha 2b treatment in an eleven-year-old boy with disseminated lymphangiomatosis

Disseminated lymphangiomatosis is a rare disease mostly observed in children and young adults. If no surgical removal can be achieved, the prognosis is poor, especially for patients with thoracic localization and pleural effusions. Next to pleural drainage, therapeutic options include radiotherapy, local, and systemic pharmacotherapy. An 11-year-old boy presented with disseminated lymphangiomatosis involving thorax with massive pleural effusions, retroperitoneum, and bones. In immunohistochemical analysis, the tissue biopsy stained positive for vascular endothelial growth factor-receptor 3 (VEGFR-3). The patient has been treated with interferon alpha 2b for 2 years, and achieved a good clinical and radiological response.

Mutation of an IKK phosphorylation site within the transactivation domain of REL in two patients with B-cell lymphoma enhances REL's in vitro transforming activity

The human c-rel proto-oncogene (REL) encodes a subunit of the nuclear factor-kappaB (NF-kappaB) transcription factor. In this report, we have identified an identical point mutation in two human B-cell lymphomas (follicular (FL) and mediastinal) that changes serine (Ser)525 (TCA) to proline (Pro) (CCA) within the REL transactivation domain. This mutation was not identified in a similarly sized cohort of healthy individuals. In the mediastinal B-cell lymphoma, the mutation in REL is of germ-line origin. In both tumors, the S525P mutant allele is over-represented. REL-S525P shows enhanced in vitro transforming activity in chicken spleen cells. REL-S525P has a reduced ability to activate the human manganese superoxide dismutase (MnSOD) promoter in A293 cells; however, the MnSOD protein shows increased expression in REL-S525P-transformed chicken spleen cells as compared to wild-type REL-transformed cells. Ser525 is a site for phosphorylation by IkappaB kinase (IKK) in vitro. The S525P mutation reduces IKKalpha- and tumor necrosis factor (TNF)alpha-stimulated transactivation by a GAL4-REL protein. Furthermore, REL-S525P-transformed chicken spleen cells are more resistant to TNFalpha-induced cell death than cells transformed by wild-type REL. These results suggest that the S525P mutation contributes to the development of human B-cell lymphomas by affecting an IKKalpha-regulated transactivation activity of REL.

Myxopapillary ependymoma of the posterior mediastinum

A left paravertebral mass discovered incidentally on routine examination in a 39-year-old woman is described. Computerized tomography studies revealed a 7 x 6 cm, well circumscribed, noncalcified soft tissue mass with lobular borders abutting the left inferior pulmonary vein and descending aorta. It was not possible to determine the exact anatomic location of the mass based on the imaging studies as both peripheral lung tumors and posterior mediastinal lesions may exhibit the imaging findings described here. At thoracotomy, the mass was seen to be well circumscribed, focally attached to the pleura but without involvement of lung parenchyma, and situated in the left posterior mediastinum. On histological examination, the lesion showed the classical features of myxopapillary ependymoma. Immunohistochemical studies confirmed this impression by demonstrating strong positivity of the tumor cells for S-100 protein, glial fibrillary acidic protein, and CD99 and negative staining with other differentiation markers. A review of the literature with a discussion of the histologic and radiologic differential diagnosis of these lesions is presented.