Clinicopathologic and DNA cytometric analysis of carcinoid tumors of the thymus

Neuroendocrine neoplasms of the thymus

Neuroendocrine neoplasms of the thymus (tNENs), including typical carcinoid, atypical carcinoid, large cell neuroendocrine carcinoma, and small cell carcinoma, are rare tumors with scarce clinical and pathological data available in the literature. They share many common features with neuroendocrine neoplasms in other organs, such as those in the lungs, while demonstrating some distinct clinical and pathological features. This review aims to give an updated overview of each category of tNENs, focusing primarily on the pathologic diagnosis and differential diagnosis of these tumors.

Genetic insights into thymic carcinomas and thymic neuroendocrine neoplasms denote prognosis signatures and pathways

BACKGROUND

Thymic carcinomas (TCs) and thymic neuroendocrine neoplasms (TNENs) are two aggressive subtypes of thymic malignancy. Traditional therapy for advanced TCs and TNENs has limited outcome. New genomic profiling of TCs and TNENs might provide insights that contribute to the development of new treatment approaches.

METHODS

We used gene panel sequencing technologies to investigate the genetic aberrations of 32 TC patients and 15 TNEN patients who underwent surgery at Shanghai Chest Hospital between 2015 and 2017. Patient samples were sequenced using a 324-gene platform with licensed technologies. In this study, we focused on clinically relevant genomic alterations (CRGAs), which are previously proven to be pathogenic alterations, to identify the pathology-specific mutational patterns, prognostic signatures of TCs and TNENs.

RESULTS

The mutational profiles between TCs and TNENs were diverse. The genetic alterations that ranked highest in TCs were in CDKN2A, TP53, ASXL1, CDKN2B, PIK3C2G, PTCH1, and ROS1 , while those in TNENs were in MEN1, MLL2, APC, RB1 , and TSC2 . Prognostic analysis showed that mutations of ROS1, CDKN2A, CDKN2B, BRAF, and BAP1 were significantly associated with worse outcomes in TC patients, and that mutation of ERBB2 indicated shortened disease-free survival (DFS) and overall survival (OS) in TNEN patients. Further investigation found that the prognosis-related genes were focused on signal pathways of cell cycle control, chromatin remodeling/DNA methylation, phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), and receptor tyrosine kinase (RTK)/RAS/mitogen-activated protein kinase (MAPK) signaling.

CONCLUSION

We profiled the mutational features of 47 Chinese patients with thymic malignancy of diverse pathologic phenotypes to uncover the integrated genomic landscape of these rare tumors, and identified the pathology-specific mutational patterns, prognostic signatures, and potential therapeutic targets for TCs and TNENs.

Combined Thymic Epithelial Neoplasms - a Review

Thymic epithelial neoplasms are the most common tumors of thymic origin but are overall rare in the general population. Their morphologic diversity, ranging from low grade to overtly malignant lesions, along with various histologic growth patterns make them a diagnostically challenging group of tumors. Very occasionally, thymomas and thymic carcinomas may develop in combination with other benign or malignant lesions of thymic origin, further complicating the diagnostic process. The focus of this review lies on the spectrum of thymic epithelial tumors that present with other thymic lesions in the same tumor mass, such as multilocular thymic cysts, neuroendocrine neoplasms, lymphomas, and germ cell tumors among others. Awareness of the existence of such unusual tumors may not only aid in their diagnosis but may also have implications for prognostic and therapeutic purposes.

A Comprehensive Review on Neuroendocrine Neoplasms: Presentation, Pathophysiology and Management

Neuroendocrine neoplasms (NENs) are a group of heterogeneous tumors with neuroendocrine differentiation that can arise from any organ. They account for 2% of all malignancies in the United States. A significant proportion of NEN patients experience endocrine imbalances consequent to increased amine or peptide hormone secretion, impacting their quality of life and prognosis. Over the last decade, pathologic categorization, diagnostic techniques and therapeutic choices for NENs-both well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs)-have appreciably evolved. Diagnosis of NEN mostly follows a suspicion from clinical features or incidental imaging findings. Hormonal or non-hormonal biomarkers (like serum serotonin, urine 5-HIAA, gastrin and VIP) and histology of a suspected NEN is, therefore, critical for both confirmation of the diagnosis and classification as an NET or NEC. Therapy for NENs has progressed recently based on a better molecular understanding, including the involvement of mTOR, VEGF and peptide receptor radionuclide therapy (PRRT), which add to the growing evidence supporting the possibility of treatment beyond complete resection. As the incidence of NENs is on the rise in the United States and several other countries, physicians are more likely to see these cases, and their better understanding may support earlier diagnosis and tailoring treatment to the patient. We have compiled clinically significant evidence for NENs, including relevant changes to clinical practice that have greatly updated our diagnostic and therapeutic approach for NEN patients.

Resection of Thymic Neuroendocrine Carcinoma Guided by Three-Dimensional Reconstruction: A Case Report

Primary thymic small cell neuroendocrine carcinoma (SCNEC), which possesses a more aggressive biological behaviour, including invasion of proximal structures, local recurrence, and distant metastasis, is extremely rare. According to a previous literature report, only a few patients with this disease have been reported, compared to patients with distant metastasis of bones, lungs, spleen, liver, and adrenal glands (1, 2). The report data suggest that SCNEC is a highly malignant tumour compared to most other tumours of the human body. In this study, we presented the case of a patient who underwent surgery guided by three-dimensional reconstruction modelling before the operation. We were fully prepared for the resection of this tumour using three-dimensional reconstruction modelling, even after reading the computed tomography (CT) images that showed a closed relationship with the pericardium, the vein of the right middle lung lobe, and the phrenic nerve. All these features demonstrate that SCNEC is highly malignant. To date, there are no procedural reports for three-dimensional reconstruction modelling in malignant thymus tumours.

Multiple endocrine neoplasia type 1 (MEN-1) and neuroendocrine neoplasms (NENs)

Neuroendocrine neoplasms (NENs) are relatively rare neoplasms with 6.4-times increasing age-adjusted annual incidence during the last four decades. NENs arise from neuroendocrine cells, which release hormones in response to neuronal stimuli and they are distributed into organs and tissues. The presentation and biological behaviour of the NENs are highly heterogeneous, depending on the organ. The increased incidence is mainly due to increased awareness and improved detection methods both in the majority of sporadic NENs (non-inherited), but also the inherited groups of neoplasms appearing in at least ten genetic syndromes. The most important one is multiple endocrine neoplasia type 1 (MEN-1), caused by mutations in the tumour suppressor gene MEN1. MEN-1 has been associated with different tumour manifestations of NENs e.g. pancreas, gastrointestinal tract, lungs, thymus and pituitary. Pancreatic NENs tend to be less aggressive when arising in the setting of MEN-1 compared to sporadic pancreatic NENs. There have been very important improvements over the past years in both genotyping, genetic counselling and family screening, introduction and validation of various relevant biomarkers, as well as newer imaging modalities. Alongside this development, both medical, surgical and radionuclide treatments have also advanced and improved morbidity, quality of life and mortality in many of these patients. Despite this progress, there is still space for improving insight into the genetic and epigenetic factors in relation to the biological mechanisms determining NENs as part of MEN-1. This review gives a comprehensive update of current evidence for co-occurrence, diagnosis and treatment of MEN-1 and neuroendocrine neoplasms and highlight the important progress now finding its way to international guidelines in order to improve the global management of these patients.

Recent advances and conceptual changes in the classification of neuroendocrine tumors of the thymus

Neuroendocrine tumors of the thymus (TNET) are exceedingly rare neoplasms. Their histomorphology is identical to neuroendocrine tumors elsewhere in the body (in particular the lungs) and bears no similarity with thymomas and thymic carcinomas. Recent molecular findings have profoundly changed our perception of these tumors and may impact future histological classification systems.

Metastatic or locally advanced mediastinal neuroendocrine tumours: outcome with 177Lu-DOTATATE-based peptide receptor radionuclide therapy and assessment of prognostic factors

BACKGROUND

Primary neuroendocrine tumours (NETs) of mediastinum are unusual tumours with aggressive biological behaviour with limited treatment options and guarded prognosis.

METHODS

Twenty-seven patients with histopathologically and radiologically proven metastatic or advanced mediastinal NET, who had undergone 177Lu-DOTATATE PRRT, were included in this retrospective analysis. Descriptive statistics was employed to calculate the cumulative overall survival (OS) and progression-free survival (PFS), determining correlation and strength of correlation between different variables with OS and PFS and finally, predictors of outcome (OS and PFS).

RESULTS

In all 27 patients enrolled and analyzed, complete symptomatic response was observed in 10 patients (37%), partial response in seven patients (25.9%), symptomatically stable disease in four patients (14.8%), and symptoms progressed or worsened in six patients (22.2%). Metabolic response evaluation demonstrated complete metabolic response in one patient (3.7%), partial metabolic response was seen in nine patients (33.3%), metabolically stable disease was seen in five patients (18.5%), and 12 patients (44.4%) showed metabolic disease progression. None of the patients achieved complete anatomical/morphological response, six (22.2%) showed partial response, seven (25.9%) showed stable disease, and in 14 patients (51.9%), there was morphological disease progression. At the time of analysis, 10 patients (37%) succumbed to the disease. The median PFS was 36 months and the median OS was 66 months. Bivariate analysis showed significant level of association of PFS with surgical intervention, higher cumulative PRRT dose, metabolic response, smaller sized primary lesion, and low lesional FDG uptake. With regard to OS, higher cumulative PRRT dose, low FDG uptake and longer PFS showed significant association.

CONCLUSION

Previous surgical intervention (including debulking surgery with R1 resection), higher cumulative dose of PRRT, and low FDG uptake of the tumour are associated with prolonged OS and PFS in patients with metastatic or advanced mediastinal NETs and were independent favourable prognostic markers.

Capecitabine and Temozolomide as a Promising Therapy for Advanced Thymic Atypical Carcinoid

BACKGROUND

Thymic atypical carcinoid (TAC) is a rare thymic neuroendocrine tumor that originates in the neuroendocrine system and lacks a standardized treatment. The combination of capecitabine (CAP) and temozolomide (TEM) is associated with an extremely high and long-lasting response rate in patients with metastatic pancreatic neuroendocrine tumors. However, there is little evidence showing that the CAPTEM regimen is effective for TAC. For patients with unresectable or metastatic atypical carcinoid of the thymus, few treatment options are available, and the treatment efficacy is not satisfactory. To explore the efficacy and safety of the CAPTEM regimen against TAC, we conducted a retrospective review.

PATIENTS AND METHODS

A total of nine patients with advanced atypical carcinoid of the thymus in the China-Japan Friendship Hospital were treated with capecitabine (750 mg/m² twice daily, days 1-14) and temozolomide (200 mg/m² once daily, days 10-14) every 28 days between 2014 and 2018. The disease control rate (DCR), progression-free survival (PFS), and adverse effects after treatment were analyzed. The DCR was calculated by RECIST version 1.1. Progression-free survival was calculated by the Kaplan-Meier survival method.

RESULTS

A total of nine patients (six male and three female) were included. The median age at CAPTEM initiation was 50 years (range, 26-58). The median number of CAPTEM cycles was 8 (range, 3-23). The DCR was 89% (8/9), with eight patients achieving stable disease. Only one patient (11%) showed progressive disease. The median PFS was 8 months. Because we applied vitamin B6 and ondansetron before administering the drugs, the side effects of this regimen were very small. Adverse reactions were all below grade 3 and included myelosuppression and digestive tract reaction.

CONCLUSION

Our results suggest that the CAPTEM regimen may be effective and well tolerated for the treatment of TAC. More evidence is needed to validate the effectiveness of this regimen.

IMPLICATIONS FOR PRACTICE

Capecitabine and temozolomide regimen is effective and well tolerated in patients with advanced thymic atypical carcinoid.

The comparison of predictive factors regarding prognoses and invasion of thymic neuroendocrine tumors preoperatively and postoperatively

Background

Thymic neuroendocrine tumors (TNT), in the anterior mediastinum, are extremely rare diseases which have significantly poor prognoses. Studies have rarely provided conclusive evidence of the prognostic factors of TNT. Standard therapies have been controversial.

Methods

TNT patients (n=173) were enrolled from Surveillance, Epidemiology and End Results database (SEER). Univariate and multivariate analyses were utilized to evaluate predictive factors of prognoses. Logistic regression analysis was used to assess the plausible correlation between histological grade, and cancer invasion. Stratification analysis was used to evaluate the effectiveness of adjuvant therapies.

Results

According to our analysis, local Masaoka stage, surgery, radiotherapy, and non-chemotherapy predicted better overall survival (OS) (P<0.05, for all) in 173 TNT patients. We found that the higher the histological grade of the tumor, the greater the rate of metastasis (P<0.05). The focus was on 125 surgically treated patients, who were females with poor prognostic factors of OS, upgraded histological grade, and advanced Masaoka stage (P<0.01, for all). The effectiveness of radiotherapy treatments had discrepancies at different clinical stages. In the local stage, radiotherapy caused significantly worse OS (P=0.011), while in the advanced stage, patients demonstrated significantly better OS with this treatment (P=0.028). Chemotherapy caused worse OS, primarily, in females (P=0.028).

Conclusions

Surgery, Masaoka stage, and adjuvant treatments were prognostic factors. With surgically treated TNT, gender, histological grade, and Masaoka stage predicted significantly worse OS. Chemotherapy decreased female patients' OS. Radiotherapy significantly promoted advanced and local advanced patients' OS; however, it decreased local stage patients' OS. Predicted TNT invasiveness significantly correlated with histological grade.

A Case Report of Metastatic Atypical Thymic Carcinoid with Ectopic ACTH Production: Locoregional Control after Adaptive Radiation Treatment

Thymic carcinoid is an extremely rare malignancy. This tumor is often associated with endocrine disorders such as Cushing's syndrome, multiple endocrine neoplasia type 1 and superior vena cava syndrome. We describe the case of a 44-year-old Italian woman with metastatic atypical thymic carcinoid secreting ectopic adrenocorticotropic hormone who was treated with adaptive radiation therapy with a curative dose schedule for a symptomatic mediastinal tumor. After 22 months, the patient was in good clinical condition, presenting stable disease without any evidence of local or systemic progression. To our knowledge there are no previously reported data regarding radical radiotherapy in the treatment of thymic carcinoids.

Treatment, prognostic markers, and survival in thymic neuroendocrine tumors: A single center experience of 41 patients

Neuroendocrine tumors of the thymus (NETTs) are rare but aggressive, and lead to poor overall survival. This retrospective study was designed to analyze factors that correlate with the prognosis of patients with NETTs.From 1999 to 2015, 41 ongoing patients with NETTs were enrolled in this study. The clinical data and outcome were compiled. Overall survival (OS) rate was analyzed using the Kaplan-Meier method in univariate analysis and the Cox-model was used in multivariate analysis.Of the 41 NETTs patients analyzed (31 male and 10 female), 12 were typical carcinoma, 14 were atypical carcinoma, 14 were small-cell carcinoma and, 1 was large-cell carcinoma. The median follow-up time was 29 months (range, 9.0-69.0). In total, 25 patients died of cancer-related disease by the last follow-up. The 3- and 5-year survival rates for all patients were 42.7% and 23.4%, respectively. Among the prognostic factors analyzed by multivariate analysis, low tumor grade, complete resection, and a negative chromogranin A (CgA) expression were positively correlated with survival.The surgical treatment of NETTs, CgA negative, and low grade of NETTs were associated with a statistically significant better prognosis. However, large, multicenter studies are required to fully validate these prognostic factors.

Classification of pulmonary neuroendocrine tumors: new insights

Neuroendocrine tumors of the lung (Lu-NETs) embrace a heterogeneous family of neoplasms classified into four histological variants, namely typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Defining criteria on resection specimens include mitotic count in 2 mm2 and the presence or absence of necrosis, alongside a constellation of cytological and histological traits including cell size and shape, nuclear features and overall architecture. Clinically, TC are low-grade malignant tumors, AC intermediate-grade malignant tumors and SCLC/LCNEC high-grade malignant full-blown carcinomas with no significant differences in survival between them. Homologous tumors arise in the thymus that occasionally have some difficulties in differentiating from the lung counterparts when presented with large unresectable or metastatic lesions. Immunohistochemistry (IHC) helps refine NE diagnosis at various anatomical sites, particularly on small-sized tissue material, in which only TC and small cell carcinoma categories can be recognized easily on hematoxylin & eosin stain, while AC and LCNEC can only be suggested on such material. The Ki-67 labeling index effectively separates carcinoids from small cell carcinoma and may prove useful for the clinical management of a metastatic disease to help the therapeutic decision-making process. Although carcinoids and high-grade neuroendocrine carcinomas in the lung and elsewhere make up separate tumor categories on molecular grounds, emerging data supports the concept of secondary high-grade NETs arising in the preexisting carcinoids, whose clinical and biological relevance will have to be placed into the proper context for the optimal management of these patients. In this review, we will discuss the selected, recent literature with a focus on current issues regarding Lu-NET nosology, i.e., classification, derivation and tumor evolution.

Thymus neuroendocrine tumors with CTNNB1 gene mutations, disarrayed ß-catenin expression, and dual intra-tumor Ki-67 labeling index compartmentalization challenge the concept of secondary high-grade neuroendocrine tumor: a paradigm shift

We herein report an uncommon association of intimately admixed atypical carcinoid (AC) and large cell neuroendocrine (NE) carcinoma (LCNEC) of the thymus, occurring in two 20- and 39-year-old Caucasian males. Both tumors were treated by maximal thymectomy. The younger patient presented with a synchronous lesion and died of disease after 9 months, while the other patient was associated with a recurrent ectopic adrenocorticotropic hormone Cushing's syndrome and is alive with disease at the 2-year follow-up. MEN1 syndrome was excluded in either case. Immunohistochemically, disarrayed cytoplasmic and nuclear ß-catenin expression was seen alongside an intra-tumor Ki-67 antigen labeling index (LI) ranging from 2 to 80% in the younger patient's tumor and from 3 to 45% in the other. Both exhibited upregulated cyclin D1 and retinoblastoma, while vimentin was overexpressed in the recurrent LCNEC only. Next-generation sequencing revealed CTNNB1, TP53, and JAK3 mutations in the synchronous tumor and CTNNB1 mutation alone in the metachronous tumor (the latter with the same mutation as the first tumor of 17 years prior). None of the 23 T-NET controls exhibited this hallmarking triple alteration (p = 0.003). These findings suggested that LCNEC components developed from pre-existing CTNNB1-mutated AC upon loss-of-function TP53 and gain-of-function JAK3 mutations in one case and an epithelial-mesenchymal transition upon vimentin overexpression in the other case. Both tumors maintained intact cyclin D1-retinoblastoma machinery. Our report challenges the concept of secondary LCNEC as an entity that develops from pre-existing AC as a result of tumor progression, suggesting a paradigm shift to the current pathogenesis of NET.

Neuroendocrine Tumors of the Thymus: Analysis of Factors Affecting Survival in 254 Patients

BACKGROUND

Neuroendocrine tumors of the thymus (NETT) constitute less than 5% of all anterior mediastinal masses but are aggressive and lead to poor overall survival. This study was designed to evaluate factors that influence the prognosis of patients with NETT and the role of surgical intervention in survival.

METHODS

We analyzed the Surveillance, Epidemiology, and End Results cancer database to identify patients with NETT. We performed univariate and multivariate analyses to identify prognostic factors among demographic, tumor, and treatment variables.

RESULTS

In 254 patients identified with NETT, the median overall survival time was 73 months, with a 5-year survival rate of 56%. Patients who underwent surgical therapy had a significantly longer median survival time than did those who did not undergo surgical therapy (109 months vs 46 months, p < 0.001). In multivariate analysis, surgical resection, Masaoka-Koga stage, and tumor size were significant predictors of survival.

CONCLUSIONS

Our study found that surgical resection, Masaoka-Koga stage, and tumor size are significant prognostic factors in patients with NETT. Complete surgical resection continues, rightfully, to be the mainstay in the treatment of this rare disease.

Long-term acquired everolimus resistance in pancreatic neuroendocrine tumours can be overcome with novel PI3K-AKT-mTOR inhibitors

Background:

The mTOR-inhibitor everolimus improves progression-free survival in advanced pancreatic neuroendocrine tumours (PNETs). However, adaptive resistance to mTOR inhibition is described.

Methods:

QGP-1 and BON-1, two human PNET cell lines, were cultured with increasing concentrations of everolimus up to 22 weeks to reach a dose of 1 μM everolimus, respectively, 1000-fold and 250-fold initial IC₅₀. Using total DNA content as a measure of cell number, growth inhibitory dose–response curves of everolimus were determined at the end of resistance induction and over time after everolimus withdrawal. Response to ATP-competitive mTOR inhibitors OSI-027 and AZD2014, and PI3K-mTOR inhibitor NVP-BEZ235 was studied. Gene expression of 10 PI3K-Akt-mTOR pathway-related genes was evaluated using quantitative real-time PCR (RT–qPCR).

Results:

Long-term everolimus-treated BON-1/R and QGP-1/R showed a significant reduction in everolimus sensitivity. During a drug holiday, gradual return of everolimus sensitivity in BON-1/R and QGP-1/R led to complete reversal of resistance after 10–12 weeks. Treatment with AZD2014, OSI-027 and NVP-BEZ235 had an inhibitory effect on cell proliferation in both sensitive and resistant cell lines. Gene expression in BON-1/R revealed downregulation of MTOR, RICTOR, RAPTOR, AKT and HIF1A, whereas 4EBP1 was upregulated. In QGP-1/R, a downregulation of HIF1A and an upregulation of ERK2 were observed.

Conclusions:

Long-term everolimus resistance was induced in two human PNET cell lines. Novel PI3K-AKT-mTOR pathway-targeting drugs can overcome everolimus resistance. Differential gene expression profiles suggest different mechanisms of everolimus resistance in BON-1 and QGP-1.

Thymic neuroendocrine tumors

Thymic neuroendocrine tumors are rare and account for approximately 2% to 5% of all thymic tumors. Despite the suggestion of benign behavior implied by their name, thymic carcinoids have been noted to present a more aggressive biologic behavior than their counterparts in other sites. Because of the lack of data, adequate-sized prospective trials are required for validation, and the enrollment of patients with advanced disease into available clinical trials is encouraged.

Tumor genetics and survival of thymic neuroendocrine neoplasms: a multi-institutional clinicopathologic study

Thymic neuroendocrine tumors (TNET) are rare primary epithelial neoplasms of the thymus. This study aimed to determine clinically relevant parameters for their classification and for therapeutic decisions. We performed a comprehensive histological, clinical, and genetic study of 73 TNET cases (13 thymic typical carcinoids [TTC], 40 thymic atypical carcinoids [TAC], and 20 high-grade neuroendocrine carcinomas [HGNEC] of the thymus), contributed by multiple institutions. The mean number of chromosomal imbalances per tumor was 0.8 in TTC (31% aberrant cases) versus 1.1 in TAC (44% aberrant cases) versus 4.7 in HGNEC (75% aberrant cases). Gains of 8q24 (MYC gene locus) were the most frequent alteration and one of the overlapping features between carcinoids and HGNEC. The 5-year survival rates for TTC, TAC, and HGNEC were 100, 60, and 30%. The 10-year survival rates for TTC and TAC were 50 and 30% (P = 0.002). Predictive mitotic cut-off values for TTC versus TAC were 2.5 per 10 high-power fields (HPF; indicating a higher death rate, P = 0.062) and 15 per 10 HPF (indicating higher risk of recurrence, P = 0.036) for separating HGNEC from TAC. We conclude that the current histopathologic classifications of TNET reflect tumor biology and provide important information for therapeutic management.

Carcinoid tumor of the thymus associated with Cushing's syndrome and dysgeusia: case report and review of the literature

A 30-year-old man was hospitalized with edema, polyuria, and abnormalities in taste. ACTH and cortisol levels at admission were markedly elevated, even after attempted suppression with 8 mg dexamethasone. A thoracic-abdominal CT revealed an anterior mediastinal lesion and hyperplasia of both adrenal glands. After excision of the mediastinal mass, which confirmed the presence of a carcinoid thymic tumor, the patient became totally asymptomatic, with normal ACTH and cortisol levels. A carcinoid thymic tumor has a poor prognosis, especially when it is associated with Cushing's syndrome. Most patients will present recidivism or metastasis within 5 years after surgery. However, the low number of cases available for analysis makes it difficult to establish optimum therapeutic approaches.

A 35-year retrospective study of carcinoid tumors in Taiwan: differences in distribution with a high probability of associated second primary malignancies

BACKGROUND

A comprehensive study of carcinoid tumors from United States-based databases indicated that the small intestine, colon, rectum, and bronchopulmonary system are common locations for carcinoid tumors. In addition, certain carcinoid tumors, such as rectal carcinoids, appeared to be overrepresented in nonwhite populations in the United States. High frequencies of associated noncarcinoid malignancies were reported in some articles. The objective of the current study was to address the organ distribution, frequency of metastasis, and survival rates of carcinoid tumors and the associated noncarcinoid tumors in Taiwanese, Asian populations.

METHODS

Two hundred twenty-eight patients with carcinoid tumors were identified and evaluated from the surgical pathology files and medical records of the Veterans General Hospital, Taipei, Taiwan from January 1970 to December 2005.

RESULTS

In 228 carcinoid tumors that were analyzed, the rectum (60.5%) was the most common location followed by the lung (20.2%) and the thymus (6.6%). Metastatic lesions were demonstrated in 16.2% of patients. Disease extent was associated with survival. The 5-year survival rates for patients with localized, regional metastatic, and distant metastatic disease were 94.1%, 49.1%, and 0%, respectively (P< .001). Associated noncarcinoid malignancies were noted in 14% of patients with carcinoids, mainly in the gastrointestinal tract (52.9%), lung, and genitourinary system.

CONCLUSIONS

A different organ distribution of carcinoids was observed in Taiwanese patients, who had with significantly more carcinoids located in the rectum and thymus compared with patients in Western countries. The patients with carcinoids in the current study had a high possibility of developing associated, noncarcinoid neoplasms. Surveillance of the colon, stomach, lung, and genitourinary system for second malignant tumors is recommended.

Distinguishing Carcinoid Tumor of the Mediastinum From Thymoma: Correlating Cytologic Features and Performance in the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology

Context.—The cytologic features of carcinoid tumor in mediastinal fine-needle aspiration are well described. Nevertheless, this tumor may be difficult to distinguish from thymoma in this site.

Objective.—We sought to correlate the cytologic features of carcinoid tumor of the mediastinum in the College of American Pathologists Interlaboratory Comparison Program in Nongynecologic Cytopathology with the frequency of misclassification as thymoma.

Design.—We reviewed 446 interpretations from 18 different cases of carcinoid tumor in mediastinum and correlated the cytologic features with performance.

Results.—Cases were more frequently classified as thymoma (158 responses, 35%) than as carcinoid tumor (126 responses, 28%). The best-performing case was classified as carcinoid tumor only 56% of the time. Three cytologic patterns were identified. Four cases consisted of isolated round cells with salt-and-pepper chromatin. Four cases consisted of isolated spindle and round cells with salt-and-pepper chromatin. The remaining 10 cases consisted of cohesive fragments of crowded cells with finely granular chromatin showing numerous pyknotic cells mimicking lymphocytes. Prominent vasculature patterns were not a feature of any of the cases. There was no correlation between any pattern and the rate of classification as carcinoid tumor or thymoma (P &gt; .05).

Conclusions.—Carcinoid tumor of the mediastinum is frequently misclassified as thymoma in this program. Although some cytologic patterns resemble thymoma, the lack of correlation of these patterns with performance suggests that at least part of the reason for misclassification may be failure to consider the correct diagnosis or a lack of familiarity with discriminating cytologic criteria.

Atypical thymoma (WHO B3) with neuroendocrine differentiation: report of a case

We report a case of type-B3 thymoma manifesting neuroendocrine differentiation. The patient was a 42-year-old woman who complained of shoulder pain but had no symptoms of myasthenia gravis or anemia. The tumor was located in the anterior mediastinum and had directly invaded the pericardium and left lung. Histological examination revealed that the tumor was lobulated by bands of fibrous tissue, perivascular spaces were scattered throughout the tumor, and there were a few intraepithelial lymphocytes. The vast majority of lymphocytes in the perivascular spaces and in the lobulated tumor were immunohistochemically positive for TdT, MIC2, and CD1a. The majority of tumor cells were polygonal and medium or large in size. The tumor cells were weakly positive for synaptophysin, chromogranin A, CD56, and NSE. Small nests of small, relatively uniform polygonal cells were observed facing the fibrous bands. These cells resembled the cells of carcinoid tumors and were strongly positive for NSE, synaptophysin, chromogranin A, and CD56. Ultrastructurally, sparse dense-core granules were observed in the cytoplasm of a few tumor cells. This is a unique case of thymoma with neuroendocrine differentiation, and to the best of our knowledge this is the first such case ever reported.

Tumeurs neuroendocrines thoraciques

Neuroendocrine pulmonary and thymic tumors constitute a distinct category of tumors collectively disclosing morphologic and biologic neuroendocrine features. They are classified in 4 histopathological types and 3 malignancy grades. The typical carcinoids are of low grade, the atypical carcinoids of intermediate grade and the large cell neuroendocrine carcinoma with the small cell carcinoma are high grade neuroendocrine tumors. Their distinction relies on objective morphologic and phenotypic criteria of strong clinical significance and predictive prognostic value.

Thymoma and Thymic Carcinoma: An Update of the WHO Classification 2004

When dealing with tumors of the thymus and mediastinum, both the surgeon and the pathologist are confronted with a vast variety of different pathohistologic entities, among which epithelial tumors, namely thymomas and thymic carcinomas, are the most frequent. Intimate knowledge of the different entities and their anticipated clinical outcome is required to meet diagnostic and therapeutic challenges. We herein briefly update the reader with the most important new changes in the 2004 WHO classification of tumors of the thymus and to important new trends in the treatment of some of these tumors.

Comparative genomic hybridization analysis of thymic neuroendocrine tumors

Thymic neuroendocrine (carcinoid) tumors are a rare neoplasm of the anterior mediastinum. The tumors frequently exhibit a wide spectrum of histology and appear to follow a more aggressive behavior than their nonthymic counterparts. Given the differing clinicopathologic manifestations, thymic neuroendocrine tumors may also possess different cytogenetic abnormalities from those that occur in foregut carcinoid tumors. In this study, we employed comparative genomic hybridization to detect genomic instability in 10 sporadic thymic neuroendocrine tumors and one multiple endocrine neoplasia type 1 (MEN1)-associated case. Gross chromosomal imbalances were found in nine cases, including gains of chromosomal material on regions X, 8, 18 and 20p and losses on 3, 6, 9q, 13q and 11q. We did not observe deletion at locus 11q13 where the MEN1 gene is located. These findings were essentially dissimilar to those reported in sporadic and MEN1-associated foregut carcinoid tumors. Consequently, we consider that a distinctive cytogenetic mechanism is at work in the development of thymic neuroendocrine tumors, which is different from that of foregut carcinoid tumors.

Pathology of thymic tumors

As the thymus is composed of heterogeneous admixture of lymphoid and epithelial elements, tumors originating in the thymus may be of varied histologic types. Thymomas are the most common thymic tumor in adults. Thymoma classification has historically been controversial, but a system put forth by the World Health Organization (WHO) in 2004 has been generally accepted as a reproducible and clinically relevant classification. In addition to histologic subtype, tumor stage and resection status are important factors in determining outcome in thymomas. Thymic lymphomas typically occur in younger patients than thymomas. The most common thymic lymphomas are precursor T-lymphoblastic lymphoma, Hodgkin lymphoma, and primary mediastinal large B-cell lymphoma. Thorough histologic sampling and, in some cases, the appropriate use of ancillary studies such as immunohistochemistry, flow cytometry, and molecular studies, are important in proper pathologic evaluation of thymic tumors.

p53, cellular proliferation, and apoptosis-related factors in thymic neuroendocrine tumors

Thymic neuroendocrine tumors are biologically aggressive neoplasms with extensive local invasion and high mortality. Although various markers of cellular proliferation and apoptosis have correlated with degrees of tumor differentiation in pulmonary neuroendocrine neoplasms, they have not been systematically studied in thymic neuroendocrine tumors. We immunostained 21 cases of thymic neuroendocrine tumors for p53, MIB-1, and the apoptosis-related markers Bcl-2, Bcl-x, and Bax. By histological classification the cases were low-grade (nine cases), intermediate-grade (eight cases), and high-grade (four cases) thymic neuroendocrine tumors. p53 was expressed in five cases: 1/9 low grade, 3/8 intermediate grade, and 2/4 high grade. The mean cellular proliferation (MIB-1) was 7.1% (range 2-12%) in low-grade thymic neuroendocrine tumors, 6.1% (range 2-15%) in intermediate-grade thymic neuroendocrine tumors, and 34.2% (range 2-80%) in high-grade thymic neuroendocrine tumors. Bcl-2 was expressed in 16 cases: 7/9 low grade, 5/8 intermediate grade, and 4/4 high grade. Bcl-x was expressed in 16 cases: 7/9 low grade, 6/8 intermediate grade, and 3/4 high grade. Bax was expressed in 13 cases: 5/9 low grade, 4/8 intermediate grade, and 4/4 high grade. The presence of mutant p53 in the tumor was associated with a statistically significant decreased mean survival (P<0.05). In contrast, either by positive or negative staining or by the score technique (staining intensity x percentage of cells staining), the presence of Bcl-x was associated with an increased mean survival (P<0.05). Finally, a Bcl-x : Bax ratio >or=1 was also associated with an increased mean survival, as compared to a Bcl-x : Bax ratio >or=1 (P<0.05). Our study shows that p53 expression and certain apoptosis markers correlate with survival. The expression of these markers may account for differences in biological behavior.

A clinicopathologic study of 12 neuroendocrine tumors arising in the thymus

STUDY OBJECTIVES

To determine whether the new classification system for thymic carcinoid tumors/neuroendocrine carcinomas provides prognostic data, and to study the presentation, diagnosis, treatment, and prognostic factors of these rare tumors.

DESIGN

Retrospective analysis.

SETTING

Royal Brompton Hospital, London, UK.

RESULTS

Eight men and four women with a median age of 58 years. Complete excision was possible in nine patients. Postoperative staging revealed two stage I tumors, two stage II tumors, three stage III tumors, one stage IVA tumor, and four stage IVB tumors. All tumors demonstrated the histopathologic features of neuroendocrine tumors, which were confirmed by positive immunohistochemical staining for chromogranin A in 11 of 12 tumors and for CD56 in 12 of 12 tumors, and the presence of dense core granules on ultrastructural analysis in 9 of 9 tumors. All 12 tumors did not stain positively for somatostatin receptors. Three tumors were grade 1, six cases were grade 2, and three cases were grade 3. Follow-up was available in all patients. One patient died 1 month postoperatively. Distant metastasis developed in nine patients (82%). Local recurrence was evident in six patients, of whom five had not received postoperative radiotherapy. Seven patients died of distant metastasis (22 to 83 months after surgery). Two are alive and disease-free (at 67 and 81 months), and two are alive with disease (at 60 and 86 months)

CONCLUSIONS

Neither grading as neuroendocrine carcinomas nor any individual histologic parameter showed a significant association with prognosis. Initial aggressive treatment, including complete surgical excision and adjuvant radiotherapy, appears to offer the best hope for prolonged survival. Adjuvant chemotherapy also should be considered, since the incidence of distant relapse is high.