[Thymomas]

Case report and literature review: thyroid carcinoma showing intrathyroid thymic carcinoma

Background

Intrathyroid thymic carcinoma (ITTC) is a rare malignancy of the thyroid gland with histological and immunophenotypic resemblance to thymic carcinoma. Surgery combined with adjuvant radiotherapy improves the survival of patients with ITTC. However, for patients with extensive metastases, there is currently no effective treatment. Chemotherapy is an option but has not demonstrated improved patient survival.

Methods and results

A female patient presented with metastases to the pleura, lung, and bone 16 years after surgery for ITTC. As radiotherapy and chemotherapy failed to control the recurrent disease, lenvatinib treatment was initiated. After 3 months, positron emission tomography/computed tomography showed a substantial reduction of all metastatic lesions and decreased tumor metabolism. The patient continues to receive lenvatinib and remains well and symptom-free.

Conclusion

For patients with ITTC who have progressive, life-threatening metastases, lenvatinib represents a valuable salvage therapy that may offer a sustained reduction in tumor burden and maintenance of quality of life.

Analysis of deep inspiration breath-hold technique to improve dosimetric and clinical advantages in postoperative intensity-modulated radiation therapy for thymomas

Background

Radiation therapy is one of the essential treatment modalities for invasive thymomas. Clinically, respiratory motion poses a challenge for the radiotherapy of thoracic tumors. One method to address this issue is to train patients to hold their breath at the end of deep inspiration. The purpose of this retrospective cohort study was to investigate the dosimetric and clinical advantages of the deep inspiration breath-hold (DIBH) technique in postoperative intensity-modulated radiation therapy (IMRT) for thymomas.

Methods

Thymoma patients undergoing postoperative IMRT were included. Each patient underwent two computed tomography (CT) scans, one under free breath (FB) and the other under DIBH. Dosimetric parameters of organs at risk (OARs) were evaluated in three series plans. Dose analysis and volume comparisons were conducted during FB-3 mm (FB with 3 mm internal target volume margin), FB-10 mm (FB with 10 mm internal target volume margin), and DIBH and compared using a paired sample Student’s t-test. Normal tissue complication probabilities (NTCP) for lungs and heart were calculated and compared.

Results

The total lung volume significantly increased by 31% (4,216±198 vs. 2,884±166 mL) and the heart volume reduced by 12% (552±25 vs. 636±35 mL) between DIBH acquisitions compared to FB. A significant improvement was observed in all the dosimetric parameters (D_mean, V20, V5) of the lung on DIBH compared to FB-3 mm (54%±2.85% vs. 47%±2.90%, P<0.001; 15%±1.37% vs. 12%±1.32%, P=0.004; and 10.28±0.58 vs. 8.76±0.57 Gy, P<0.001, respectively), as well as in the D_max and D2% of the esophagus and spine. The lung volume increment was related to a reduction in the mean dose of lungs, with a correlation coefficient of r=0.27, P=0.03. The NTCP values for pneumonitis significantly reduced with DIBH compared to the FB state (0.6% vs. 1.1%, P<0.001).

Conclusions

The radiation dose to the OARs can be significantly reduced by using the DIBH technique in postoperative IMRT for thymomas. The increased volume of lungs using DIBH acquisitions can significantly reduce the incidence of pneumonitis.

A case of thymoma in myasthenia gravis: Successful outcome after thymectomy

INTRODUCTION

Thymic abnormalities occur as hyperplasia and thymoma. Myasthenia gravis is commonly present in thymoma. Thymectomy possesses risk due to anatomical proximity with vital thoracic structures and myasthenia crisis.

PRESENTATION OF CASE

Forty five years female with complaints of difficulty swallowing and weakness of upper limb muscles upon investigation showed mass in mediastinum and antibody test for myasthenia gravis positive. Medical management was done for a month followed by thymectomy. There were no intra and postoperative complications. Medical management was stopped one month after surgery and she is symptom free.

DISCUSSION

Thymectomy is the standard of care where median sternotomy is the mainstay approach to surgery. Various other surgical approaches and complications revolving around surgery has been discussed.

CONCLUSION

Surgical removal of thymoma cured myasthenia gravis in our case. We focused on proper preoperative optimization of myasthenia gravis symptoms before thymectomy.

Primary mediastinal neoplasms: a report of 1,005 cases from a single institution

BACKGROUND

This study was an epidemiological analysis of all primary mediastinal neoplasms (PMNs) diagnosed between 2000 and 2016 at the National Tuberculosis and Lung Diseases Research Institute, Poland.

METHODS

All patients with any mediastinal abnormality were included in the analysis. The patients' age and gender were obtained from the institutional database.

RESULTS

From a cohort of 5,108 patients, 3,691 primary mediastinal lesions were found, including 1,005 (19%) PMNs: lymphomas (533, 53% of PMNs), thymomas (215, 21%), neurogenic tumors (NTs) (100, 10%), germ cell tumors (GCTs) (62, 6%), soft tissue tumors (STTs) (47, 5%) and thymic carcinomas/thymic neuroendocrine tumors (TCs/TNETs) (37 in total, 4%). The most frequent lymphomas were classical Hodgkin lymphomas [256] and primary mediastinal large B-cell lymphomas [163]. Type AB [73] predominated in thymomas and squamous cell carcinomas [9] and carcinoids [10] in TCs/TNETs. NTs encompassed mainly schwannomas [49], ganglioneuromas [21] and neurofibromas [10]. The most frequent STTs were hemangiomas [13] and lymphangiomas [11]. Lymphomas, thymomas and NT were more often in women, TCs/TNETs in men (P<0.001). Lymphomas predominated between the 2nd and 4th decade of life, NTs under the 3rd decade and thymic epithelial tumors between the 6th and 8th decade (P<0.001). There was no correlation between the subtypes of thymomas and the patients' gender (P=0.389) but it was found between histology and patients' age: in patients <30 years of age type B2 and B3 thymomas and >70 years of age AB type and micronodular thymomas with lymphoid stroma (P<0.001) predominated. In the group of GCTs half of them were malignant and these were noted exclusively in men. No correlation between subtypes of NTs or TCs/TNETs and patients' age and gender was found (P>0.05).

CONCLUSIONS

PMNs are rare conditions thus awareness of basic epidemiology may be very helpful for final diagnosis.

[Thymic carcinomas]

Thymic carcinomas (TC) are approximately 10 times less prevalent than thymomas but of high clinical relevance because they are more aggressive, less frequently resectable than thymomas and usually refractory to classical and targeted long-term treatment approaches. Furthermore, in children and adolescents TC are more frequent than thymomas and particularly in this age group, germ cell tumors need to be a differential diagnostic consideration. In diagnostic terms pathologists face two challenges: a), the distinction between thymic carcinomas and thymomas with a similar appearance and b), the distinction between TC and histologically similar metastases and tumor extensions from other primary tumors. Overcoming these diagnostic challenges is the focus of the new WHO classification of thymic epithelial tumors. The objectives of this review are to highlight novel aspects of the WHO classification of thymic carcinomas and to address therapeutically relevant diagnostic pitfalls.