Thymic carcinomas: clinicopathologic study of 37 cases from a single institution

Clinical characteristics and prognosis of primary thymic adenocarcinoma: A single-center retrospective analysis

BACKGROUND

Primary thymic adenocarcinoma (PTAC) is an extremely rare disease with a poor prognosis. In the present study, we sought to analyze the clinical characteristics and prognostic factors of patients with PTAC.

METHODS

A total of 14 patients with PTAC treated at our center from January 2000 to January 2019 were included in this study. We retrospectively collected information on sex, age, history of smoking, family history of cancer, comorbidities, symptoms, imaging tests, serum tumor marker levels, tumor, node, metastasis (TNM) staging, and treatment records. Follow-up information was obtained by telephone interviews or outpatient clinic visit. Univariate and multivariate Cox regression analyses were performed to investigate the clinicopathological factors associated with survival.

RESULTS

Among 14 patients with PTAC, there were five males and nine females, with an average age of 48.7 ± 9.3 years. A total of 23.1% of the patients had a history of smoking. The clinical symptoms of the patients were nonspecific and seven patients had elevated levels of serum tumor markers. Surgery was performed for nine patients, among which only four received R0 resection. The median survival time of the 14 patients was 16.0 months, and the 1-, 3- and 5-year survival rates were 57.1%, 35.7% and 21.4%, respectively. TNM stage was identified as an independent prognostic factor for PTAC patients (the median survival time of stage I-IIIA vs. stage IV was 44.0 months vs. 9.0 months, p = 0.002).

CONCLUSIONS

PTAC is highly aggressive malignancy with poor prognosis. Surgical treatment is feasible, but R0 resection is challenging. TNM staging is significantly associated with patient survival.

Thymic epithelial tumours: histopathological classification and differential diagnosis

The epithelial and lymphoid compartments of the thymus can give rise to a wide variety of tumours, including thymomas, thymic carcinomas, lymphoreticular proliferations, germ cell tumours, and sarcomas. While some of these have close similarity to their counterparts in other organs, both in terms of histology and immunohistochemistry, as well as molecular features, others are unique to the thymus. The epithelial tumours, which can develop in the thymus, will be discussed in this review, with a particular emphasis on resolving differential diagnosis by means of morphology, immunohistochemical profiles, and molecular diagnostics.

Thymic Epithelial Tumors: An Evolving Field

Despite their rarity, thymic epithelial tumors (TETs) have attracted much interest over the years, leading to an impressive number of histological and staging classifications. At present, TETs are divided by the WHO classification into four main subtypes: type A, type AB, and type B thymomas (subdivided into B1, B2, and B3), and thymic carcinomas, going from the more indolent to the most aggressive ones. Among many debated staging proposals, the TNM and the Masaoka-Koga staging systems have been widely accepted and used in routine practice. The four-tiered histological classification is symmetrically mirrored by the molecular subgrouping of TETs, which identifies an A-like and an AB-like cluster, with frequent GTF2I and HRAS mutations; an intermediate B-like cluster, with a T-cell signaling profile; and a carcinoma-like cluster comprising thymic carcinomas with frequent CDKN2A and TP53 alterations and a high tumor molecular burden. Molecular investigations have opened the way to tailored therapies, such as tyrosine kinase inhibitors targeting KIT, mTOR, and VEGFR, and immune-checkpoints that have been adopted as second-line systemic treatments. In this review, we discuss the crucial events that led to the current understanding of TETs, while disclosing the next steps in this intriguing field.

CD70 in Thymic Squamous Cell Carcinoma: Potential Diagnostic Markers and Immunotherapeutic Targets

CD70 – a ligand protein of CD27 on lymphocytes – is expressed in a large spectrum of malignancies. It is an attractive target for antibody-based therapy and several clinical trials are currently being conducted. However, there is no evidence regarding the expression of CD70 and its relationship with expression of programmed death ligand-1 (PD-L1) and CD27+ tumor-infiltrating lymphocytes (TIL) in formalin-fixed paraffin-embedded (FFPE) tissues of thymic tumors. FFPE tissues of thymic squamous cell carcinoma (TSCC) (operative specimens, n = 31; biopsy specimens, n = 11), thymoma (n = 60), thymic carcinoid (n = 3), and lung squamous cell carcinoma (LSCC) (n = 30) were analyzed immunohistochemically. Immunoreactivity for CD70 was semi-quantitatively scored according to the proportion of positive tumor cells. Moreover, the densities of CD27-positive intratumoral TIL (iTIL) and stromal TIL of TSCC were assessed and survival was compared. Most TSCC cases (87%; 27/31) were CD70-positive. In contrast, all thymoma and thymic carcinoid cases were CD70-negative. In LSCC cases, CD70-positivity was significantly lower than TSCC cases (20%; 6/30). Biopsy and resected specimens obtained from the same patients demonstrated a consistent staining pattern (6/6 patients). The proportion of CD70-positive TSCC was comparable with those of CD5 (87%) and CD117 (90%). Correlation between CD70 and PD-L1 expression score was observed. There was no significant difference in survival between the CD70-high and CD70-low expression groups. Meanwhile, patients with CD27-positive iTIL-high tumors exhibited better survival than those with iTIL-low tumors. This tendency was weaker in the CD70-high subset. CD70 immunohistochemistry is useful in diagnosing TSCC. CD70 may prevent anti-tumor immunity via CD27. Immunotherapy targeting the CD70–CD27 axis may be a promising option for the treatment of TSCC.

Narrative review of immunotherapy in thymic malignancies

Thymomas and thymic carcinomas (TCs) (also known as Thymic Epithelial Tumors or TETs) are rare cancers and the most frequent masses of the anterior mediastinum. These tumors appear in the epithelial component of the thymus, a primary lymphoid organ, and they have reported a high risk of auto-immunity due to a unique biology. Indeed, up to 30% of patients with TETs could present an autoimmune disorder (AID), the most frequent being Myasthenia Gravis (MG). Moreover, AIDs have been reported not only at tumor diagnosis but before and during the follow-up. These tumors have a lack of specific therapeutic targets for metastatic setting. Immune checkpoint inhibitors (ICI) may defeat cancer cells' capacity to evade the immune system and proliferate. The long-term benefit of ICIs in the metastatic setting in several tumors, such as melanoma or non-small cell lung cancer (NSCLC), let to evaluate ICI approaches in TETs. The high rate of AIDs and distribution of autoimmune events among TET's histological subtypes may have an influence on the decision regarding a treatment based on ICI due to the increased risk of toxicity. We summarize the current evidence for the efficacy of ICI in thymoma and TC and discuss several unresolved challenges and concerns for the use of this agents in TETs.

Micronodular thymic carcinoma with lymphoid hyperplasia: relevance of immunohistochemistry with a small panel of antibodies for diagnosis-a RYTHMIC study

Micronodular thymic carcinoma with lymphoid hyperplasia (MNTCLH) is a rare form of thymic carcinoma. We present the experience of RYTHMIC, the French national network devoted to the treatment of thymic epithelial tumors through multidisciplinary tumor boards with a review of all tumors by pathologists for classification and staging. Six cases of MNTCLH were diagnosed during a review of 1007 thymic epithelial tumors. Histologically, epithelial cells with atypia and mitoses formed micronodules that were surrounded by an abundant lymphoid background with follicles. There was neither obvious fibro-inflammatory stroma nor necrosis. Spindle cells areas were common. Initial diagnosis was micronodular thymoma in two cases, cellular atypia being overlooked, eclipsed by the micronodular pattern. Immunohistochemistry with a panel of five antibodies showed that cytokeratins (AE1-AE3) and p63-positive epithelial cells also expressed CD5 and that there was no TdT-positive cells within the tumors. CD20 highlighted the lymphoid hyperplasia. Additionally epithelial cells also expressed CD117 and diffusely Glut 1. Twenty-seven micronodular thymomas with lymphoid stroma diagnosed during the same period did not show the CD5 and CD117 positivities seen in MNTCLH and contained TdT-positive lymphocytes. Three of the 6 patients with MNTCLH had adjuvant radiotherapy. Three patients with follow-up information were alive without recurrence at 38, 51, and 95 months. Our study shows that immunohistochemistry, such as that used in the RYTHMIC network with a small panel of antibodies, may easily help to confirm the correct diagnosis of MNTCLH, a rare and low-aggressive form of thymic carcinoma, and avoid the misdiagnosis of micronodular thymoma.

Common and rare carcinomas of the thymus

Thymic carcinoma encompasses a diverse group of rare tumors that occur almost exclusively in the prevascular (anterior) mediastinum. Thymic carcinomas have a worse outcome than thymomas with a median time to death of under 3 years. These tumors lack the typical lobulation of thymomas, exhibit commonly more cytologic atypia, are associated with a desmoplastic stromal reaction, and lack thymocytes, features that distinguish them from thymomas. The most common thymic carcinoma is squamous cell carcinoma; other subtypes include mucoepidermoid carcinoma, NUT carcinoma, and adenocarcinoma, among others. Largely due to multi-institutional and global efforts and meta-analysis of case reports and series, some of the thymic carcinoma subtypes have been studied in more detail and molecular studies have also been performed. Morphology and immunophenotype for the vast majority of thymic carcinoma subtypes are similar to their counterparts in other organs. Therefore, the distinction between thymic carcinoma and metastatic disease, which is relatively common in the prevascular mediastinum, can be challenging and in general requires clinical and radiologic correlation. Although surgical resection is the treatment of choice, only 46 to 68% of patients with thymic carcinoma can undergo resection as many other tumors present at high stage with infiltration into vital neighboring organs. These patients are usually treated with chemotherapy and/or radiation. The search for better biomarkers for prognosis and treatment of thymic carcinomas is important for improved management of these patients and possible targeted therapy.

[Thymoma and squamous thymic carcinoma diagnosis; experience from the RYTHMIC network]

The RYTHMIC network, supported by the French National Cancer Institute is dedicated to the management of patients with thymic epithelial tumors through regional and national multidisciplinary tumor boards. Tumor board decisions are based on the initial pathology diagnoses. However, following clinical inclusion in the network, a central pathology review is organized, implicating a panel of pathologists, for histotype and stage classification, which is different from a classical second opinion from pathologist to pathologist for a difficult case. Thanks to the participation of all French pathologists, more than 1000 cases have been reviewed by the panel. The aim of this review is to share with the French pathology community, the experience of the group. It underlines the importance of macroscopy and surgeon-pathologist involvement to allow a good central review, the main histopathological and immunophenotypical patterns of the most frequent thymomas and thymic carcinoma types, the differential diagnoses, as well as the difficulties for the panel to reproducibly assess on slides, stage, for some cases.

Diagnostic Roles of Immunohistochemistry in Thymic Tumors: Differentiation between Thymic Carcinoma and Thymoma

Background: The present study aims to evaluate the diagnostic roles of various immunohistochemical (IHC) markers in thymic tumors, including thymic carcinoma (TC) and thymoma (TM). Methods: Eligible studies were obtained by searching the PubMed databases and screening the searched articles. Thirty-eight articles were used in the present meta-analysis and included 636 TCs and 1861 TMs. Besides, for IHC markers with statistical significance, a diagnostic test accuracy review was performed. Results: The comparison of various IHC expressions between TC and TM was performed for 32 IHC markers. Among these IHC markers, there were significant differences between TC and TM for beta-5t, B-cell lymphoma 2 (Bcl-2), calretinin, CD1a, CD5, carcinoembryonic antigen (CEA), cytokeratin19 (CK19), CD117, glucose transporter 1 (Glut-1), insulin-like growth factor 1 receptor (IGF-1R), mesothelin, MOC31, mucin1 (MUC1), p21, and terminal deoxynucleotidyl transferase (TdT). Markers with higher expressions in TCs were Bcl-2, calretinin, CD5, CEA, CD117, Glut-1, IGF-1R, mesothelin, MOC31, MUC1, and p21. Among these markers, there were no significant differences between TC and TM type B3 in immunohistochemistries for Bcl-2 and CK19. On the other hand, β-catenin and CD205 showed a considerable difference in IHC expressions between TC and TM type B3, but not between TC and overall TM. In diagnostic test accuracy review, MUC1 and beta-5t were the most useful markers for TC and TM, respectively. Conclusions: Taken together, our results showed that the expression rates for various IHC markers significantly differed between TC and TM. The IHC panel can be useful for differentiation from limited biopsied specimens in daily practice.

Tobacco smoking and alcohol consumption as risk factors for thymoma - A European case-control study

PURPOSE

Hardly anything is known about the aetiology of thymoma. This paper presents data regarding tobacco smoking and alcohol consumption in relation to thymoma from the first case-control study performed on this rare tumour.

METHODS

A European multi-centre case-control study including incident cases aged 35-69 years with thymoma between 1995 and 1997, was conducted in seven countries. A set of controls, used in seven parallel case-control studies by the same research group was used, including population-based controls from five countries and hospital controls with colon cancer from two countries. Altogether 103 cases, accepted by a reference pathologist, 712 colon cancer controls, and 2071 population controls were interviewed.

RESULTS

Tobacco smoking was moderately related with thymoma (OR 1.4, 95% CI 0.9-2.2), and a tendency to dose-response was shown (p = 0.04), with an increased risk for heavy smokers defined as ≥41 pack-years (OR 2.1, 95% CI 1.1-3.9). A high consumption of spirits defined as ≥25 g of alcohol per day was associated with an increased risk of thymoma (OR 2.4, 95% CI 1.1-5.4), whereas no association was found with beer or wine.

CONCLUSIONS

Tobacco smoking and a high intake of spirits were indicated as risk factors for thymoma.

Efficacy of chest computed tomography prediction of the pathological TNM stage of thymic epithelial tumours

OBJECTIVES

The aim of this study is to evaluate the efficacy of chest computed tomography (CT) to predict the pathological stage of thymic epithelial tumours (TET) using the recently introduced tumour, node and metastasis (TNM) staging with comparison to the modified Masaoka staging.

METHODS

Preoperative chest CT examinations in cases of resected TET with sampled lymph nodes (2006-2016) were retrospectively reviewed by 2 thoracic radiologists and radiologically (r) staged using both staging systems. A thoracic pathologist reviewed all cases for the pathological (p) stage. Concordance between r-staging and p-staging was assessed by % agreement and unweighted kappa statistics. Associations between r-stage and p-stage with outcomes were assessed using the Cox proportional hazards regression.

RESULTS

Sixty patients with TET were included (47 thymomas, 12 thymic carcinomas and 1 atypical carcinoid tumour). Sixteen patients (26.7%) had received neoadjuvant therapy. Fifty-four patients (90.0%) had complete resection. The overall agreement between the r-stage and p-stage was 66.7% (κ = 0.46) for TNM staging and 46.7% (κ = 0.30) for modified Masaoka staging. Agreement between r-assessment and p-assessment of the T, N and M components of the TNM stage was 61.7% (κ = 0.28), 86.7% (κ = 0.48) and 98.3% (κ = 0.88), respectively. CT overstaged 12 patients (20.0%) for TNM staging and 12 patients (20.0%) for modified Masaoka staging and understaged 8 (13.3%) and 20 (33.3%) patients for TNM staging modified Masaoka staging, respectively. The r-TNM staging accuracy was lower for patients with neoadjuvant therapy (50.0% with vs 72.7% without). During a median follow-up of 2.6 years (range 0.1-10.5 years), 12 patients had metastases and/or recurrence; 11 patients died (4 of disease). The r-TNM stage and modified Masaoka stage were associated with overall survival and progression-free survival (P < 0.001).

CONCLUSIONS

Preoperative chest CT is able to accurately predict p-TNM stage in two-thirds of surgically resected TET, with an agreement between radiological staging and pathological staging superior to the modified Masaoka staging.

Expression of PD-L1/PD-1 in lymphoepithelioma-like carcinoma of the thymus

Poorly differentiated non-keratinizing squamous cell carcinoma of the thymus, also known as lymphoepithelioma-like carcinoma, is a rare primary malignant neoplasm of thymic origin. The mainstay of treatment for these tumors is surgical and they tend to respond poorly to chemotherapy. The checkpoint programmed cell death ligand-1 protein (PD-L1) bound to its receptor (PD-1) has been demonstrated to be an important therapeutic target for many different tumors. Expression of PD-L1/PD-1 in lymphoepithelioma-like carcinoma of the thymus may indicate that these tumors are potential targets for inhibitor therapy. Twenty-one cases of lymphoepithelioma-like carcinoma of the thymus were collected and reviewed. Tissue microarrays were created using triplicate 2 mm cores for each case. PD-L1/PD-1 staining pattern (neoplastic cells versus tumor infiltrating lymphocytes) was documented for each case. Out of 21 cases, 15 (71.4%) showed various degrees of membranous PD-L1 staining. Of the positive cases, 48% showed high expression of PD-L1 (>50% of tumor cells) and 24% showed low expression (<50%). PD-1 staining showed focal positivity in 12/20 (60%) cases among tumor infiltrating lymphocytes. PD-L1/PD-1 inhibitor therapy has been applied successfully in other solid malignant tumors with high expression of PD-L1/PD-1. The high level of PD-L1 expression in our cases indicates that PD-L1 may play a role in the pathogenesis of these tumors and that PD-L1/PD-1 blockade may be a viable therapeutic option for patients with lymphoepithelioma-like carcinoma of the thymus who have failed other first-line therapies.

Spinal Metastasis Resulting from Atypical Thymic Carcinoid: A Case Report

BACKGROUND

Thymic carcinoid with spinal metastasis is an extremely rare entity. Clinically, the tumor presents either by its endocrine manifestations or by mechanical compression of surrounding structures. However, no previously published case studies have reported neck pain and neurologic deficit in the initial presentation of an atypical thymic carcinoid.

CASE DESCRIPTION

A 56-year-old man, a nonsmoker, presented with a 12-month history of intermittent neck pain and a 1-month history of progressive numbness and weakness of the right upper limb. Cervical MRI showed multiple abnormal signals and C2 soft-tissue mass intruding into the vertebral canal. Cervical CT scan showed multiple bone lesions. The diagnosis of thymic carcinoid was obtained by preoperative lymph node biopsy. The patient underwent cervical laminectomy and occipitocervical fixation. Significant alleviation of pain and neurologic improvement were achieved. The postoperative pathological examination confirmed the diagnosis of thymic carcinoid.

CONCLUSIONS

Neck pain and neurologic deficit could be the first presentation of thymic carcinoid with spinal metastasis. Palliative surgery is an effective method to improve quality of life in patients with thymic carcinoid with spinal metastasis.

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.

Adaptive hypofractionated gamma knife radiosurgery in the acute management of large thymic carcinoma brain metastases

BACKGROUND

Brain metastases often lead to serious neurological impairment and life threatening states. Their acute management remains complex, particularly in the case of rare malignancies with aggressive evolution. In large single lesions, open surgery followed by radiation to the surgical cavity is widely regarded as the best approach; yet in many cases, microsurgery is not feasible due to the lesion's critical location and/or the number of brain metastases present. We report the effects of adaptive hypofractionated gamma knife radiosurgery in the acute management of critically located thymic carcinoma metastases.

CASE DESCRIPTION

A 50-year-old male with metastatic thymic carcinoma was treated with radiosurgery for two large supratentorial brain metastases (M3 and M4) adjacent to eloquent areas and one smaller cerebellar metastasis (M2). M3 and M4 were treated with adaptive hypofractionated gamma knife radiosurgery, showing a dramatic volume reduction 4 weeks after treatment completion without radiation-induced side effects. Thirteen months later, two new small, threatening supratentorial lesions (M5-M6) were treated with the same technique. Interestingly, M2 (treated with standard single fraction) and M5-M6 developed local adverse radiation events. The patient's general and neurological status remained next to normal by the time of paper submission.

CONCLUSION

The application of adaptive hypofractionated radiosurgery in this acute setting proved effective in terms of rapid tumor ablation, with salvage of neurological functionality and limited toxicity. We have called the overall procedure rapid rescue radiosurgery (RRR). A systematic study of past and ongoing RRR-treatments is warranted and in progress.

Recent advances in the management of endocrine malignancies associated with hereditary hyperparathyroidism syndromes

Hereditary hyperparathyroidism syndromes, such as multiple endocrine neoplasm type 1, type 2A and the hyperparathyroidism-jaw tumor syndrome, are associated with an increased incidence of malignancies involving the neuroendocrine tissue of the pancreas and thymus, parathyroid and thyroid glands. The natural history of these endocrine tumors can differ from nonhereditary malignancies. The surgical approach, the only potentially curative treatment option for these endocrine malignancies, has evolved considerably in recent years. Newer targeted therapies, such as small molecule kinase inhibitors, somatostatin analogs and peptide receptor radionuclide therapy, are being developed. We provide here a comprehensive review of the current standards of treatment and emerging novel therapies for the endocrine malignancies commonly associated with hereditary hyperparathyroidism syndromes.

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.

CD52, CD22, CD26, EG5 and IGF-1R expression in thymic malignancies

BACKGROUND

Thymic epithelial tumours are rare cancers for which new treatment options are required. Identification of putative predictive markers is important for developing clinical trials. We studied the expression of five putative predictive biomarkers, potentially actionable by approved experimental drugs.

METHODS

CD52, CD22, CD26, EG5, and IGF-1R expression were investigated by immunohistochemistry in formalin-fixed surgical samples of thymic epithelial tumour patients. All samples containing 10% positive epithelial tumour cells, independent of tumour cell intensity, were considered as positive. Correlation with histological subtype was performed.

RESULTS

106 surgical samples (89 thymomas, 12 thymic carcinoma, and 5 thymic neuroendocrine tumours) were evaluated. Overall, CD52, CD22, CD26, EG5 and IGF-1R expression was observed in 7%, 42%, 25%, 42% and 77% of samples, respectively. CD52 expression was more frequent in B2 and B3 thymoma. All TET subtypes stained for CD22, mainly AB thymoma (68%). CD26 expression also correlated with AB thymoma (68%), and A thymoma (50%) subtype, while IGFR1 was the most common marker expressed by thymic carcinoma samples (92%), followed by EG5 (60%). Only EG5 expression was significantly higher in thymic carcinomas than in thymomas (75% vs. 38%, p=0.026).

CONCLUSIONS

Our data were consistent with a previous study of IGF-1R expression. Based on their expression, activity of agents targeting CD52, CD 22, CD26 and EG5 could be further explored in TET patients.

Utility of Cluster of Differentiation 5 and Cluster of Differentiation 117 Immunoprofile in Distinguishing Thymic Carcinoma from Pulmonary Squamous Cell Carcinoma: A Study on 1800 Nonsmall Cell Lung Cancer Cases

Background

Mediastinum harbors a mixed bag of neoplastic lesions with varied therapeutic and prognostic implications. Distinguishing pulmonary squamous cell carcinoma from thymic carcinoma is a challenging task owing to rather nonspecific clinicoradiological features and a considerable overlap in histomorphological features. Thus, we evaluated the diagnostic utility of cluster of differentiation 5 (CD5) and CD117 immunohistochemical markers in distinguishing these tumors.

Materials and Methods

The archives of department of histopathology were retrospectively reviewed from June 2012 to May 2016. Formalin-fixed paraffin-embedded blocks of 1800 cases diagnosed as nonsmall cell lung carcinoma were retrieved, and immunohistochemical expression of CD5 and CD117 was evaluated in these cases.

Results

Adenocarcinoma (980; 54.44%) was the most common histological subtype of lung carcinoma observed in our study. CD117 was positive in 171 out of 1800 cases (9.5%) of which 120 cases (70.17%) were adenocarcinoma, followed by 40 cases (23.4%) of squamous cell carcinoma. Immunoreactivity for CD5 was observed in 209 cases (11.61%), 200 (95.7%) cases of which were diagnosed as adenocarcinoma. None of the cases diagnosed as squamous cell carcinoma on histomorphology showed CD5 immunoexpression.

Conclusion

While thymic squamous cell carcinomas are well known for CD5 and CD117 coexpression, none of the cases of squamous cell carcinoma arising in lung express CD5. These markers are a diagnostic tool to distinguish a primary lung squamous cell carcinoma from thymic carcinoma, particularly in the setting of a central pulmonary lesion with mediastinal involvement.

Comparison of outcomes between neuroendocrine thymic tumours and other subtypes of thymic carcinomas: a joint analysis of the European Society of Thoracic Surgeons and the International Thymic Malignancy Interest Group

OBJECTIVES

The latest World Health Organization (WHO) histological classification divides thymic epithelial tumours in thymomas and thymic carcinomas (TCs), the latter also including the neuroendocrine thymic tumours (NETTs). NETTs and other TC histotypes have been described to have a significantly lower survival than thymomas, but these two groups of tumours have rarely been compared directly. Using the European Society of Thoracic Surgeons and the International Thymic Malignancy Interest Group datasets, we wanted to study this issue.

METHODS

This is a retrospective multicentre cohort study of patients operated for TC. Outcome measures were overall survival (OS) and recurrence-free survival (RFS). OS was analysed using the Kaplan-Meier method and RFS was assessed using competing risk analysis. The association with clinical and prognostic factors for OS and RFS was evaluated with log-rank test and Gray's test, respectively.

RESULTS

A total of 1247 tumours (1042 TCs) were collected between 1984 and 2012. A R0 resection was performed in 363 TCs and in 52 NETTs. The median follow-up was 4.4 years for TCs and 4.1 years for NETTs. Owing to the missing values for survival information, a total of 728 TC patients and 132 NETTs were included in the OS analysis. Among them, 262 TC and 39 NETT patients died. The median OS was 6.6 years for TC and 7.5 years for NETTs. The overall 5-year survival rates were 60% for TC and 68% for NETTs; 10-year survival rates were 40% for TCs and 39% for NETTs (P = 0.19). Five-year RFS was 0.35 and 0.34 for TCs and NETTs (P = 0.36). On multivariate analysis, histology did not influence either OS (P = 0.79) or RFS (P = 0.59).

CONCLUSIONS

This represents the largest clinical series of TCs and NETTs collected. Despite the biological aggressiveness of these rare neoplasms, the 5-year survival rate after resection is over 60% and TCs and NETT showed a similar rate of survival and recurrences after surgery.

Endocrine neoplasms in familial syndromes of hyperparathyroidism

Familial syndromes of hyperparathyroidism, including multiple endocrine neoplasia type 1 (MEN1), multiple endocrine neoplasia type 2A (MEN2A), and the hyperparathyroidism-jaw tumor (HPT-JT), comprise 2-5% of primary hyperparathyroidism cases. Familial syndromes of hyperparathyroidism are also associated with a range of endocrine and nonendocrine tumors, including potential malignancies. Complications of the associated neoplasms are the major causes of morbidities and mortalities in these familial syndromes, e.g., parathyroid carcinoma in HPT-JT syndrome; thymic, bronchial, and enteropancreatic neuroendocrine tumors in MEN1; and medullary thyroid cancer and pheochromocytoma in MEN2A. Because of the different underlying mechanisms of neoplasia, these familial tumors may have different characteristics compared with their sporadic counterparts. Large-scale clinical trials are frequently lacking due to the rarity of these diseases. With technological advances and the development of new medications, the natural history, diagnosis, and management of these syndromes are also evolving. In this article, we summarize the recent knowledge on endocrine neoplasms in three familial hyperparathyroidism syndromes, with an emphasis on disease characteristics, molecular pathogenesis, recent developments in biochemical and radiological evaluation, and expert opinions on surgical and medical therapies. Because these familial hyperparathyroidism syndromes are associated with a wide variety of tumors in different organs, this review is focused on those endocrine neoplasms with malignant potential.

Ectopic thymic carcinoma presenting as an intrathoracic mass

An asymptomatic 83-year-old man was found to have a right intrathoracic tumor. Computed tomography demonstrated a soft-tissue density mass measuring 55 × 25 × 22 mm adjacent to the right anterior chest wall. At surgery, the tumor was found to adhere to the diaphragm and right lung, contiguous with the mediastinal fat tissue. Histology of the resected specimen demonstrated proliferation of spindle and sarcomatous cells with multinucleated giant cells. Thus the tumor was diagnosed as undifferentiated thymic carcinoma and was considered to have arisen from ectopic thymic tissue. At 2 years postoperatively, the patient had no evidence of recurrence.

Imaging in multiple endocrine neoplasia type 1: recent studies show enhanced sensitivities but increased controversies

In multiple endocrine neoplasia type 1 (MEN1) patients, a number of recent studies compare the ability of different, new imaging modalities to existing modalities to localize the important neuroendocrine tumors (NETs) that contribute to their decreased life expectancy (pancreatic NETs [pNETs] and thymic carcinoids). These included the use of ⁶⁸Ga-DOTATOC-PET/CT, endoscopic ultrasound and MRI. The current paper analyzes these results in light of current guidelines and controversies involved in the treatment/management of MEN1 patients. Particular attention is paid to results in these studies with thymic carcinoids and nonfunctional pNETs/gastrinomas, which recent studies show are particularly important in determining long-term survival. These studies show a number of promising imaging results but also raise a number of controversies, which will need to be addressed both in their use initially and for serial studies in these patients.

Differential diagnostic value of CD5 and CD117 expression in thoracic tumors: a large scale study of 1465 non-small cell lung cancer cases

Background

Thoracic pathologists are frequently faced with tissue specimens from intrathoracic/mediastinal tumors. Specifically the differentiation between thymic and pulmonary squamous cell carcinomas (SqCC) can be challenging. In order to clarify the differential diagnostic value of CD5 and CD117 in this setting, we performed a large scale expression study of both markers in 1465 non-small cell lung cancer (NSCLC) cases.

Methods

Tissue microarrays of formalin-fixed paraffin-embedded resection specimens of 1465 NSCLC were stained with antibodies against CD117 and CD5. Positivity of both markers was correlated with clinicopathological variables.

Results

CD117 was positive in 145 out of 1457 evaluable cases (9.9 %) and CD5 was positive in 133 out of 1427 evaluable cases (9.3 %). 28 cases (1.9 %) showed coexpression of CD117 and CD5. Among the 145 cases that were positive for CD117, 97 (66.8 %) were adenocarcinomas (ADC), 34 (23.4 %) were SqCC, 5 (3.4 %) were adenosquamous carcinomas (ADSqCC), 8 (5.5 %) were large cell carcinomas (LC), and one (0.6 %) was a pleomorphic carcinoma (PC). In the CD5 positive group consisting of 133 cases, 123 (92.4 %) were ADC, 0 (0 %) were SqCC, 4 (3.0 %) were ADSqCC, 3 (2.2 %) LC and 3 (2.2 %) were PC. None of the 586 SqCC showed expression of CD5. No association of CD117- or CD5 positivity to patients’ age, pathological stages or to T-, N-, or M- categories was observed.

Conclusions

A substantial subset of NSCLC exhibit positivity of CD117 and CD5. Since CD5 expression was not observed in pulmonary SqCC, but is expressed in the majority of thymic squamous cell carcinomas, the application of this immunomarker is a valuable tool in the differential diagnosis of thoracic neoplasms.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-015-0441-7) contains supplementary material, which is available to authorized users.

Prognostic factors of patients with thymic carcinoma after surgery: a retrospective analysis of 58 cases

BACKGROUND

Thymic carcinoma is reputed to carry a poor prognosis. Although few scholars have studied the prognosis of thymic carcinoma, the prognostic factors of patients after surgery are not well established. We analyze the prognostic significance of undetermined factors to predict the survival of patients after surgery.

METHODS

We reviewed 351 cases of thymic epithelial tumor treated with surgery at a single institution in China from 1992 to 2011. A total of 58 patients were histopathologically reconfirmed as having thymic carcinoma. Clinicopathological characteristics and treatment modalities were reviewed. During the follow-up, with a median of 65.8 months, survival time was analyzed using the Kaplan-Meier method. Univariate and multivariate analysis were performed to identify prognostic factors.

RESULTS

The overall 3-, 5-, and 10-year survival rate was 69.0, 43.1, and 12.1%, respectively. The Log-rank test revealed that Masaoka stage (p = 0.000), histology group (p = 0.000), completeness of the resection (p = 0.000), great vessel invasion (p = 0.000), and presence of symptoms (p = 0.003) were significant prognostic factors in all patients. However, tumor size (p = 0.086), age (p = 0.677), sex (p = 0.706), smoking (p = 0.065), and alcohol (p = 0.875) were not prognostic factors. A Cox proportional hazards regression model showed that Masaoka stage (hazard ratio = 15.640, p = 0.000) and completeness of the resection (hazard ratio = 18.303, p = 0.000) were the only independent prognostic factors.

CONCLUSIONS

The Masaoka stage and completeness of the resection were independent prognostic factors that predicted long-term survival of patients with thymic carcinoma treated with surgery.

Thymic carcinoma: a cohort study of patients from the European society of thoracic surgeons database

INTRODUCTION

Thymic carcinoma is a rare and aggressive thymic neoplasm. The European Society of Thoracic Surgeons developed a retrospective database collecting patients undergoing resection for thymic tumors from 1990 to 2010.

METHODS

Of 2265 patients with thymic tumors, there were 229 thymic carcinomas. Clinicopathological characteristics were analyzed including age, associated paraneoplastic diseases, stage (Masaoka-Koga), World Health Organization histologic subtypes, type of resection (total/subtotal/biopsy/no resection), tumor size, pre/postoperative treatments, and recurrence. Outcome measures included overall survival (OS), freedom from recurrence, and cumulative incidence of recurrence.

RESULTS

A complete resection was achieved in 140 patients (69%). Recurrence occurred in 54 patients (28%). Five- and 10-year OS rates were 0.61 and 0.37. Five- and 10-year freedom from recurrence rates were 0.60 and 0.43. Cumulative incidence of recurrence was 0.21 (3 yr), 0.27 (5 yr), and 0.32 (10 yr). Survival was better after surgical resection versus biopsy/no resection (p < 0.001), after complete resection versus subtotal resection (p < 0.001), and when using Masaoka-Koga system (stages I-II versus III versus IV) (p < 0.001). The use of multidisciplinary treatments resulted in a survival advantage which was significant in the surgery + radiotherapy group (p = 0.02). Incomplete resection (p < 0.0001) and advanced stage (Masaoka-Koga III-IV) (p = 0.02) had a negative impact on OS at multivariable analysis. Administration of adjuvant radiotherapy was beneficial in increasing OS (p = 0.02).

CONCLUSIONS

The results of our study indicate that patients with thymic carcinoma should undertake surgical resection whenever possible; a complete resection and early Masaoka-Koga stage are independent predictors of improved survival; our results also suggest that postoperative radiotherapy is beneficial in improving survival.