Thymic neoplasms: a clinical update

Are the minimally invasive techniques the new gold standard in thymus surgery for myasthenia gravis? Experience of a reference single-site in VATS thymectomy

The thymus is the primary lymphoid organ responsible for the maturation and proliferation of T lymphocytes. During the first years of our lives, the activation and inactivation of T lymphocytes occur within the thymus, facilitating the correct maturation of central immunity. Alterations in the positive and negative selection of T lymphocytes have been studied as the possible origins of autoimmune diseases, with Myasthenia Gravis (MG) being the most representative example. Structural alterations in the thymus appear to be involved in the initial autoimmune response observed in MG, leading to the consideration of thymectomy as part of the treatment for the disease. However, the role of thymectomy in MG has been a subject of controversy for many years. Several publications raised doubts about the lack of evidence justifying thymectomy's role in MG until 2016 when a randomized study comparing thymectomy via sternotomy plus prednisone versus prednisone alone was published in the New England Journal of Medicine (NEJM). The results clearly favored the group of patients who underwent surgery, showing improvements in symptoms, reduced corticosteroid requirements, and fewer recurrences over 3 years of follow-up. In recent years, the emergence of less invasive surgical techniques has made video-assisted or robotic-assisted thoracoscopic (VATS/RATS) thymectomy more common, replacing the traditional sternotomy approach. Despite the increasing use of VATS, it has not been validated as a technique with lower morbidity compared to sternotomy in the treatment of MG. The results of the 2016 trial highlighted the benefits of thymectomy, but all the patients underwent surgery via sternotomy. Our hypothesis is that VATS thymectomy is a technique with lower morbidity, reduced postoperative pain, and shorter postoperative hospital stays than sternotomy. Additionally, VATS offers better clinical improvement in patients with MG. The primary objective of this study is to validate the VATS technique as the preferred approach for thymectomy. Furthermore, we aim to analyze the impact of VATS thymectomy on symptoms and corticosteroid dosage in patients with MG, identifying factors that may predict a better response to surgery.

Evaluation of the relationship between the eighth edition of TNM staging, the mMasoaka, and World Health Organization histopathological classification for thymoma

AIM OF STUDY

The aim of this study was to describe the correlation between the eighth tumor, node, and metastasis (TNM), mMasaoka staging, and the World Health Organization (WHO) histopathologic classification and to identify prognostic values in predicting survival and recurrence of thymoma.

MATERIALS AND METHODS

Medical files of 90 patients with thymoma diagnosed between 1992 and 2018 were evaluated for this trial.

RESULTS

The distributions of patients were similar between mMasaoka and eighth TNM staging according to early (I, II) and advanced stages (IIIA, IIIB, IV). Interestingly, 55 of 63 stage I patients with TNM staging showed difference as 31 of them up-staged to stage IIA and 24 of them up-staged to stage IIB in mMasoaka staging. Both staging systems closely correlated with WHO classification (p < 0.001); stages I and II were associated with low-risk groups (type A, AB, B1), and stages III and IV were associated with high-risk groups (type B2, B3). WHO classification was not a prognostic factor for overall survival (OS) ( P = 0.13) and progression-free survival (PFS) (p = 0.08), but it was a prognostic factor for 10-year cancer-specific survival (CSS) (p = 0.04). Myasthenia gravis was associated to early stages (stage I, II) (p = 0.007) and related with better prognosis.

CONCLUSIONS

Our study showed a correlation between both staging system and WHO classification. A certain difference was found between eighth TNM staging and the mMasoaka staging in terms of stage I disease. Both staging systems effectively prognosticated OS, CSS, and PFS. To clarify the prognostic relevance and clinical usefulness of the WHO classification may be beneficial in clinical practice for the treatment decision.

Possible roles of genetic variations in chemotherapy related cardiotoxicity in pediatric acute lymphoblastic leukemia and osteosarcoma

Background

The treatment of acute lymphoblastic leukemia (ALL) and osteosarcoma (OSC) is very effective: the vast majority of patients recover and survive for decades. However, they still need to face serious adverse effects of chemotherapy. One of these is cardiotoxicity which may lead to progressive heart failure in the long term. Cardiotoxicity is contributed mainly to the use of anthracyclines and might have genetic risk factors. Our goal was to test the association between left ventricular function and genetic variations of candidate genes.

Methods

Echocardiography data from medical records of 622 pediatric ALL and 39 OSC patients were collected from the period 1989–2015. Fractional shortening (FS) and ejection fraction (EF) were determined, 70 single nucleotide polymorphisms (SNPs) in 26 genes were genotyped. Multivariate logistic regression and multi-adjusted general linear model were performed to investigate the influence of genetic polymorphisms on the left ventricular parameters. Bayesian network based Bayesian multilevel analysis of relevance (BN-BMLA) method was applied to test for the potential interaction of the studied cofactors and SNPs.

Results

Our results indicate that variations in ABCC2, CYP3A5, NQO1, SLC22A6 and SLC28A3 genes might influence the left ventricular parameters. CYP3A5 rs4646450 TT was 17% among ALL cases with FS lower than 28, and 3% in ALL patients without pathological FS (p = 5.60E-03; OR = 6.94 (1.76–27.39)). SLC28A3 rs7853758 AA was 12% in ALL cases population, while only 1% among controls (p = 6.50E-03; OR = 11.56 (1.98–67.45)). Patients with ABCC2 rs3740066 GG genotype had lower FS during the acute phase of therapy and 5–10 years after treatment (p = 7.38E-03, p = 7.11E-04, respectively). NQO1 rs1043470 rare T allele was associated with lower left ventricular function in the acute phase and 5–10 years after the diagnosis (p = 4.28E-03 and 5.82E-03, respectively), and SLC22A6 gene rs6591722 AA genotype was associated with lower mean FS (p = 1.71E-03), 5–10 years after the diagnosis.

Conclusions

Genetic variants in transporters and metabolic enzymes might modulate the individual risk to cardiac toxicity after chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4629-6) contains supplementary material, which is available to authorized users.

Malignant thymoma with metastasis associated with paraneoplastic myasthenia gravis

We describe a patient who initially presented with a mixed thymic tumor and developed myasthenia gravis 8 years following thymectomy with recurrence of metastatic disease. Metastasis to the pleura, mediastinum, and cervical spine was identified with a positron emission tomography scan when this patient presented with recurring pneumonias and atrial fibrillation. The presentation and diagnosis were clouded by multiple courses of prednisone and chemotherapy for respiratory complications and metastatic disease, respectively. Classical myasthenia gravis symptoms emerged when his prednisone was tapered. The delayed presentation of paraneoplastic disease and the rare metastatic site make this case particularly unusual.

99mTc MIBI THYMIC SCINTIGRAPHY IN DIAGNOSIS AND THERAPEUTIC DECISION MAKING: WHAT IS BEHIND THE IMAGE?

CONTEXT

Despite CT being generally used in thymic pathology, in the case of regions with the same tissue density, only functional radioisotopic imaging can hint towards malignity.

OBJECTIVES

To assess the usefulness of 99mTc MIBI scintigraphy for diagnosis and treatment planning in thymoma, in relation with the radiotracer uptake mechanism.

PATIENTS AND METHODS

99mTc MIBI thymic scans for 19 patients diagnosed with thymic disorders were assessed using tumor uptake ratio (UR). Specimens of thymectomies were examined and cytological assessments were correlated with the UR.

RESULTS

The UR of all surgical patients was higher than 1.2, with a 1.5 cutoff between lymphoid hyperplasia and thymoma. The UR values were correlated with the histopathologic diagnosis (Pearson correlation 0.91, significant at p<0.01). The highest UR was 3.24, found in the case of an AB thymoma where the rate lymphocytes/epithelial cells (L/E) was 1.6. In B1 thymoma UR was 1.14 and L/E was 2.46.

CONCLUSION

Phenotype differences between thymoma types correlate with 99mTc MIBI cellular uptake: lower rate L/E corresponds to higher UR, higher malignity potential and invasiveness. A thymic 99mTc MIBI UR higher than 1.5, corresponding to a CT tumoral image, is suggestive for a thymoma, requiring surgical treatment first.

A Case Series of Patients With Autoimmune Myasthenia Gravis in Association With Invasive Thymoma

OBJECTIVES

In some patients, autoimmune myasthenia gravis (MG) is associated with thymic hyperplasia or thymoma, and in some patients the thymoma is invasive. Little is known about the clinical course of subjects who present with MG and are found to have invasive thymoma.

METHODS

We reviewed the patients at our clinic with MG and invasive thymoma, and have described their clinical features.

RESULTS

Six MG patients were diagnosed with invasive thymoma. The subjects had extensive multimodal therapy. Two subjects died from uncontrolled neuromuscular respiratory failure despite aggressive immunosuppression, 2 subjects had other autoimmune disorders (Morvan syndrome and polymyositis), and 2 subjects are controlled on immunosuppression.

CONCLUSIONS

Patients with invasive thymoma and MG can have a poor outcome, with difficulty in controlling myasthenic symptoms and can have other clinically important autoimmune diseases.

Development of combined thymic carcinoma and thymoma in an extrathymic lesion during long follow-up for recurrent thymoma

The present study reported a rare case of combined thymic squamous cell carcinoma and thymoma exhibiting a mass on the left chest wall. The patient underwent thoracotomy for invasive thymoma 15 years previously, however, suffered a relapse in the left intrathoracic space. Radiotherapy, chemotherapy and partial resection, as secondary surgery for the intrathoracic mass, were performed. The histological findings in the resected specimens revealed type B3 thymoma. As the patient developed a left chest wall mass and pain in 2013, the mass was resected. The histological findings indicated two separate components composed of type B3 thymoma and squamous cell carcinoma. Immunohistological findings revealed that the thymoma cells were positive for CD5, while the thymic carcinoma cells were negative for CD5. Several reports have demonstrated the coexistence of thymic carcinoma and thymoma in the primary thymus, however, the development of a combined tumor in an extrathymic lesion is extremely rare. The present case had a long follow-up for recurrent thymoma. The present case indicated that the development and/or coexistence of malignant components in the thymoma must be taken into consideration for the treatment and/or management of patients with thymoma and that a pre-existence of CD5 expression in thymoma and the lost change may be associated with the process of malignant transformation.

A case of co-existing paraganglioma and thymoma

Background

Head and neck paragangliomas are rare tumours and can arise as a part of inherited syndromes. Their association with thymic tumour is not well known.

Case description

This report describes a female patient who presented with right sided neck paragangliomas. The histology of the tumour was consistent with paraganlioma. Few years later her MRI scan of the chest revealed presence of an anterior mediastinal mass that corresponded to the location of the thymus. Review of her previous scans showed that the mass was present all along and had gradually increased in size. Patient developed symptoms including fatigue, dyspnoea, migratory polyarthritis, Raynaud’s phenomenon and erythema nodosum. She had sternotomy and excision of mediastinal mass. The histology was consistent with cortical thymoma (WHO type B2) and she had radiotherapy. After treatment her constitutional symptoms improved. Her paraganglioma susceptibility genes are negative.

Discussion and evaluation

To our knowledge this is only the second case report in the literature of coexistence of carotid body tumour and thymoma. The first case reported was bilateral carotid body tumour, thyroid gland adenoma and thymoma. This case also highlights the importance of long term surveillance, multidisciplinary management and being aware of associated pathologies in patients with isolated paraganglioma.

Myasthenia gravis associated with invasive malignant thymoma: two case reports and a review of the literature

Introduction

Approximately ten to fifteen percent of patients with myasthenia gravis are found to have a thymoma, and twenty to twenty-five percent of patients with thymoma have myasthenia gravis. Thymomatous myasthenia gravis tends to have a difficult clinical course and poor prognosis.

Case presentation

We report two cases (one patient of Asian ethnicity and the other of Caucasian ethnicity) of atypical presentations of myasthenia gravis associated with invasive malignant thymoma. Both patients were diagnosed at a young age, in their 20s. They presented with a turbulent course of myasthenia gravis and recurrent thymoma, but obtained good outcome after aggressive treatment involving multiple different specialists.

Conclusions

Although thymomatous myasthenia gravis tends to have a difficult clinical course and poor prognosis, early and aggressive treatment along with multidisciplinary management may improve the outcome of these patients.

Molecular markers for patients with thymic malignancies: not feasible at present?

BACKGROUND

Thymomas and thymic carcinomas are rare malignancies and devising clinically effective molecular targeted therapies is a major clinical challenge. The aim of the study was to analyze BLC2 and vascular endothelial growth factor receptor (VEGFR) expression and KRAS and EGFR mutational status and to correlate them with the clinical characteristics of patients with thymomas and thymic carcinomas.

MATERIALS AND METHODS

A total of 62 patients (mean age: 50.4 ± 13.2 years) with thymomas and thymic carcinomas were enrolled. The expression of BLC2 and VEGFR in tumor cells and normal tissues was evaluated by RT-PCR. The mutational status of the KRAS and EGFR genes was investigated by PCR with sequence specific primers.

RESULTS

The BLC2 and VEGFR expression levels did not differ significantly between tumor and normal tissues. Moreover, there were no clearly pathogenic mutations in KRAS or EGFR genes in any tumor. None of the molecular markers were significantly related to clinical outcomes.

CONCLUSIONS

Changes in levels of expression of BLC2 and VEGFR do not appear to be involved in thymic tumorigenesis. Moreover, our data suggest that KRAS and EGFR mutations do not play a major role in the pathogenesis of thymomas and thymic carcinomas.

Type AB thymoma is not a mixed tumor of type A and type B thymomas, but a distinct type of thymoma

Type AB thymoma is generally regarded to be a mixture of type A and type B thymomas, but has not been studied extensively. In this study, we precisely investigated the characteristics of type AB thymoma immunohistochemically and compared it with other types of thymoma, including type A, metaplastic, and type B1 thymoma. In type A thymoma, the tumor cells were composed solely of pan-cytokeratin (CK-AE1/AE3)(+) claudin-1(+) vimentin(-) epithelial membrane antigen (EMA)(-) short spindle cells. Metaplastic thymoma exhibited biphasic architecture of epithelial islands of short spindle cells, which were phenotypically almost identical to the tumor cells in type A thymoma, and anastomosing bundles of CK-AE1/AE3(-) claudin-1(-) vimentin(+) EMA(+) fibroblast-like long spindle-shaped epithelial cells. Interestingly, we found that there were two distinctive subtypes of cell in type AB thymoma: the conventional subtype and the metaplastic subtype. The conventional subtype is characterized by type A-like components resembling type A thymoma. The metaplastic subtype is characterized by type A-like components extensively resembling the anastomosing bundles of fibroblast-like long spindle epithelial cells. Interestingly, the metaplastic subtype was a major subtype (14/19 cases), while the conventional subtype was a minor one (5/19 cases). In contrast to the rarity of metaplastic thymoma, the metaplastic subtype of type AB thymoma appears to be a major subtype of type AB thymoma.