Primary Mediastinal Tumors. Part 1*: Tumors of the Anterior Mediastinum

doi:10.1378/chest.112.2.511

Chest

Volume 112, Issue 2, August 1997, Pages 511-522

https://doi.org/10.1378/chest.112.2.511 Get rights and content

Primary anterior mediastinal neoplasms comprise a diverse group of tumors and account for 50% of all mediastinal masses. Thymomas are most common and can be locally invasive and associated with parathymic syndromes. Thymic carcinomas and thymic carcinoids are rare malignancies with a propensity for local invasion and distant metastases. Thymolipomas are benign thymic tumors. The mediastinal germ cell tumors are a heterogeneous group of benign and malignant neoplasms. Mediastinal lymphangiomas are rare tumors and predominantly occur in young children. In contrast, mediastinal goiters are relatively common in adults. Mediastinal parathyroid adenomas are an uncommon cause of persistent hyperparathyroidism and rarely cause a discernible mass. The clinical, radiologic, and therapeutic aspects of the most common masses are reviewed.

Section snippets

Thymoma

Thymoma is the most common primary tumor of the anterior mediastinum.1, 5, 6 Men and women are equally affected and most patients are adults older than 40 years.5, 7, 8, 9 Thymomas are rare in children and adolescents. Most patients are asymptomatic, although one third experience chest pain, cough, dyspnea, and/or other symptoms related to compression or invasion of adjacent structures.¹⁰ Depending on the series, up to one half of patients suffer from one or more parathymic syndromes, most

Thymic Carcinoma

The thymic carcinomas are a heterogeneous group of aggressive epithelial malignancies that have a strong propensity for early local invasion and widespread metastases. Squamous cell carcinoma and lymphoepithelioma-like carcinoma are the most common cell types and usually occur in middle-aged men with a mean age of 46 years.28, 29 Their malignant cytologic features distinguish them from both encapsulated and invasive thymomas as the latter are cytologically benign.³⁰ An occult primary lung

Thymic Carcinoid

Thymic carcinoid is a rare malignancy that is histologically identical to carcinoid tumors at other sites. It typically affects men in the fourth to fifth decades of life.34, 35 Approximately 50% of patients have endocrine abnormalities, most commonly Cushing syndrome due to ectopic adrenocorticotropin hormone production or multiple endocrine neoplasia syndrome.5, 34 The classic carcinoid syndrome is rarely associated with thymic carcinoid.³⁶ Patients may also be asymptomatic or experience

Thymolipoma

Thymolipoma is a rare benign slow-growing neoplasm of the thymus that affects male and female subjects equally over a wide age range. However, young adults (with a mean age of 27 years) are most commonly afflicted.³⁸ Approximately half of the patients are asymptomatic.

Thymolipoma is a large, soft, encapsulated mass composed of mature adipose cells and thymic tissue.⁵ Twenty-five percent of tumors weigh more than 2 kg. Radiologically, thymolipoma is a large anterior mediastinal mass that

Nonneoplastic Thymic Cysts

Thymic cysts are rare and represent approximately 3% of all anterior mediastinal masses.⁴ Their etiology is controversial. Thymic cysts may be congenital³⁹ or acquired, either due to inflammation or in association with an inflammatory neoplasm such as Hodgkin's lymphoma, seminoma, or thymic carcinoma.40, 41 Congenital thymic cysts are thought to be remnants of the thymopharyngeal duct and can be found anywhere along the embryologic course of the thymus as it migrates from the neck into the

Mediastinal Germ Cell Tumors

Mediastinal germ cell tumors (teratomas, seminomas, and nonseminomatous malignant germ cell tumors) are a heterogeneous group of benign and malignant neoplasms thought to originate from primitive germ cells “misplaced” in the mediastinum during early embryogenesis.42, 43 The anterior mediastinum, especially the anterosuperior portion, is the most common extragonadal primary site.42, 44 Mediastinal germ cell tumors represent approximately 10 to 15% of adult anterior mediastinal tumors1, 42 and

Mediastinal Lymphangioma

Mediastinal lymphangioma (cystic hygroma) is a histologically benign⁶⁰ proliferation of interconnecting lymphatic vessels and sacs that may grow in an infiltrative fashion.⁶¹ Its etiology is controversial; some authors suggest it is a developmental lesion⁶¹ while others postulate it has a hamartomatous or neoplastic origin.60, 61 Lymphangioma is typically a tumor of very young children. Fifty percent are present at birth and 90% are discovered by 2 years of age.60, 62 Ninety-five percent

Mediastinal Goiter

While mediastinal goiter represents only 10% of mediastinal masses in surgical series,¹ it is one of the most commonly seen in clinical practice. Twenty percent of cervical goiters descend into the thorax, usually into the left anterior superior mediastinum.⁶⁵ Infrequently, they can extend behind the trachea and involve the middle and posterior mediastinal compartments. Primary intrathoracic goiters without a cervical component are very rare.⁶⁶ These tumors rarely contain foci of malignancy.

Mediastinal Parathyroid Adenoma

A parathyroid adenoma is a benign functioning neoplasm that occurs most commonly in the neck. Ten percent of tumors are ectopic⁶⁸ and almost half⁶⁹ occur in the anterior mediastinum, usually near or within the thymus due to a common embryologic origin from the third and fourth brachial pouches.⁷⁰ Older women are most commonly affected and present with signs and symptoms of hyperparathyroidism that persist following cervical parathyroidectomy.

Pathologically, mediastinal parathyroid adenomas are

Conclusion

Many mediastinal masses are serendipitously discovered on chest radiographs obtained for other reasons. Some patients will come to clinical attention with vague chest complaints or with signs and symptoms related to compression or invasion of mediastinal structures.

The most common primary anterior mediastinal tumors are thymoma, teratoma, substernal goiter, and lymphoma. All other lesions are extremely rare. Patients with anterior mediastinal masses should be evaluated preoperatively for

ACKNOWLEDGMENT

Special thanks to Vivian L. McBride for her expertise in preparing the manuscript.

References (73)

SP Benjamin et al.
Primary tumors of the mediastinum
Chest
(1972)
RD Davis et al.
Primary cysts and neoplasms of the mediastinum: recent changes in clinical presentation, methods of diagnosis, management and results
Ann Thorac Surg
(1987)
TI Morgenthaler et al.
Thymoma
Mayo Clin Proc
(1993)
EW Wilkins et al.
Cases of thymoma at the Massachusetts General Hospital
J Thorac Cardiovasc Surg
(1966)
K Yokoi et al.
Invasive thymoma with intracaval growth into right atrium
Ann Thorac Surg
(1992)
GC Economopoulos et al.
Carcinoid tumors of the thymus
Ann Thorac Surg
(1990)
GM Graeber et al.
Cystic lesions of the thymus
J Thorac Cardiovasc Surg
(1984)
CR Nichols
Mediastinal germ cell tumors: clinical features and biologic correlates
Chest
(1991)
FH Dexeus et al.
Genetic abnormalities in men with germ cell tumors
J Urol
(1988)
BD Lewis et al.
Benign teratoma of the mediastinum
J Thorac Cardiovasc Surg
(1983)

C Aygun et al.

Primary mediastinal seminoma

Urology

(1984)

DE Johnson et al.

Metastases from testicular carcinoma

Urology

(1976)

DP Thompson et al.

Acute thoracic distress in childhood due to spontaneous rupture of a large mediastinal teratoma

J Pediatr Surg

(1969)

RH Knapp et al.

Malignant germ cell tumors of the mediastinum

J Thorac Cardiovasc Surg

(1985)

LR Brown et al.

Intrathoracic lymphangioma

Mayo Clin Proc

(1986)

DM Yousem et al.

Thyroid and parathyroid gland pathology

Otolaryngol Clin North Am

(1995)

CR Hopkins et al.

Thyroid and parathyroid imaging

Semin Ultrasound CT MR

(1995)

AR Wychulis et al.

Surgical treatment of mediastinal tumors

J Thorac Cardiovasc Surg

(1972)

RS Fraser et al.

The normal chest

J Rosai et al.

Tumors of the thymus

R Lattes

Thymoma and other tumors of the thymus: an analysis of 107 cases

Cancer

(1962)

RW O'Gara et al.

Tumors of the anterior mediastinum

Cancer

(1958)

JE Lewis et al.

Thymoma: a clinicopathologic review

Cancer

(1987)

AG Verstandig et al.

Thymoma—report of 71 cases and a review

Crit Rev Diagn Imaging

(1992)

G Maggi et al.

Thymomas: a review of 169 cases with particular reference to results of surgical treatment

Cancer

(1986)

JV Souadjian et al.

The spectrum of diseases associated with thymoma

Arch Intern Med

(1974)

KE Osserman et al.

Studies in myasthenia gravis: review of a 20-year experience in over 1200 patients

Mt Sinai J Med

(1971)

VA Lennon et al.

Auto antibodies to acetylcholine receptors in myasthenia gravis

N Engl J Med

(1983)

FM Howard et al.

Clinical correlation of antibodies that bind, block or modulate human acetylcholine receptors in myasthenia gravis

Ann NY Acad Sci

(1987)

J Kimura

Post-thymectomy myasthenia gravis: report of a case of ocular myasthenia gravis after total removal of a thymoma and review of the literature

Neurology

(1967)

TA Walderman

Thymoma, hypogammaglobulinemia, and absence of eosinophils

J Clin Invest

(1967)

EA Zerhouni et al.

Invasive thymomas: diagnosis and evaluation by CT

J Comput Assist Tomogr

(1982)

M Korobkin et al.

Case report: intracaval and intracardiac extension of malignant thymoma: CT diagnosis

J Comput Assist Tomogr

(1989)

ML Rosado de Christenson et al.

Thymoma: radiologic-pathologic correlation

Radiographics

(1992)

CA Moran et al.

Thymomas presenting as pleural tumors

Am J Surg Pathol

(1992)

JC Scatarige et al.

Transdiaphragmatic extension of invasive thymoma

AJR Am J Roentgenol

(1985)

Cited by (321)

Spatiotemporal distribution of mediastinal neoplasms: A comprehensive multi-center study
2024, Lung Cancer
Mediastinal neoplasms are typical but uncommon thoracic diseases with increasing incidence and unfavorable prognoses. A comprehensive understanding of their spatiotemporal distribution is essential for accurate diagnosis and timely treatment. However, previous studies are limited in scale and data coverage. Therefore, this study aims to elucidate the distribution of mediastinal lesions, offering valuable insights into this disease.
This multi-center, hospital-based observational study included 20 nationwide institutions. A retrospective search of electronic medical records from January 1st, 2009, to December 31st, 2020, was conducted, collecting sociodemographic data, computed tomography images, and pathologic diagnoses. Analysis focused on age, sex, time, location, and geographical region. Comparative assessments were made with global data from a multi-center database.
Among 7,765 cases, thymomas (30.7%), benign mediastinal cysts (23.4%), and neurogenic tumors (10.0%) were predominant. Distribution varied across mediastinal compartments, with thymomas (39.6%), benign cysts (28.1%), and neurogenic tumors (51.9%) most prevalent in the prevascular, visceral, and paravertebral mediastinum, respectively. Age-specific variations were notable, with germ cell tumors prominent in patients under 18 and aged 18–29, while thymomas were more common in patients over 30. The composition of mediastinal lesions across different regions of China remained relatively consistent, but it differs from that of the global population.
This study revealed significant heterogeneity in the spatiotemporal distribution of mediastinal neoplasms. These findings provide useful demographic data when considering the differential diagnosis of mediastinal lesions, and would be beneficial for tailoring disease prevention and control strategies.
Pure mediastinal seminoma about a case report
2023, Radiology Case Reports
Mediastinal Seminoma is one of the malignant germ cell tumors of the mediastinum. It is a rare tumor that represents only 1%-4% of mediastinal tumors. We report the case of a patient treated at the Oncology Center of Oujda for a pure primitive seminoma of the mediastinum, with a review of the literature to assess the epidemiological, clinical, therapeutic, and prognostic characteristics of this pathology. This is a 25-year-old man whose aunt is being treated for breast cancer and who complained of persistent dry cough with asthenia without any other associated signs. The initial imaging revealed a voluminous locally advanced tumor process in the anterior and middle mediastinum. Tumor markers Alpha-fetoprotein (AFP) and beta-subunit of chorionic gonadotrophic hormone (BHCG) were normal, as well as testicular ultrasound. The CT- guided transthoracic biopsy with anatomopathological study and immunohistochemistry was in favor of a pure seminoma. The treatment consisted of primary chemotherapy with BEP protocol. The response was favorable with a significant reduction in tumor size estimated at 90%. The residual tumor was inoperable due to its intimate contact with the vascular structures and was treated with external radiotherapy at a total dose of 36 Gy. The evolution at 20 months after treatment was in favor of a good clinical and radiological evolution.
Pan-mediastinal neoplasm diagnosis via nationwide federated learning: a multicentre cohort study
2023, The Lancet Digital Health
Mediastinal neoplasms are typical thoracic diseases with increasing incidence in the general global population and can lead to poor prognosis. In clinical practice, the mediastinum's complex anatomic structures and intertype confusion among different mediastinal neoplasm pathologies severely hinder accurate diagnosis. To solve these difficulties, we organised a multicentre national collaboration on the basis of privacy-secured federated learning and developed CAIMEN, an efficient chest CT-based artificial intelligence (AI) mediastinal neoplasm diagnosis system.
In this multicentre cohort study, 7825 mediastinal neoplasm cases and 796 normal controls were collected from 24 centres in China to develop CAIMEN. We further enhanced CAIMEN with several novel algorithms in a multiview, knowledge-transferred, multilevel decision-making pattern. CAIMEN was tested by internal (929 cases at 15 centres), external (1216 cases at five centres and a real-world cohort of 11 162 cases), and human–AI (60 positive cases from four centres and radiologists from 15 institutions) test sets to evaluate its detection, segmentation, and classification performance.
In the external test experiments, the area under the receiver operating characteristic curve for detecting mediastinal neoplasms of CAIMEN was 0·973 (95% CI 0·969–0·977). In the real-world cohort, CAIMEN detected 13 false-negative cases confirmed by radiologists. The dice score for segmenting mediastinal neoplasms of CAIMEN was 0·765 (0·738–0·792). The mediastinal neoplasm classification top-1 and top-3 accuracy of CAIMEN were 0·523 (0·497–0·554) and 0·799 (0·778–0·822), respectively. In the human–AI test experiments, CAIMEN outperformed clinicians with top-1 and top-3 accuracy of 0·500 (0·383–0·633) and 0·800 (0·700–0·900), respectively. Meanwhile, with assistance from the computer aided diagnosis software based on CAIMEN, the 46 clinicians improved their average top-1 accuracy by 19·1% (0·345–0·411) and top-3 accuracy by 13·0% (0·545–0·616).
For mediastinal neoplasms, CAIMEN can produce high diagnostic accuracy and assist the diagnosis of human experts, showing its potential for clinical practice.
National Key R&D Program of China, National Natural Science Foundation of China, and Beijing Natural Science Foundation.
Ultrasound-guided needle aspiration biopsy of isolated anterior mediastinal masses
2023, Pulmonology
Diagnostic approach for mediastinal masses with radiopathological correlation
2023, European Journal of Radiology
Mediastinal masses have various histopathological and radiological findings. Although lymphoma is the most common type of tumor, thymic epithelial and neurogenic tumors are common in adults and children, respectively, but several other types are difficult to distinguish. No previous review has simply and clearly shown how to differentiate mediastinal masses.
We conducted a review of the latest mediastinal classifications and mass differentiation methods, with a focus on neoplastic lesions. Both older and recent studies were searched, and imaging and histopathological findings of mediastinal masses were reviewed. Original simple-to-use differentiation flowcharts are presented.
Assessing localizations and internal characteristics is very important for mediastinal mass differentiation. The mass location and affected organ/tissue should be accurately assessed first, followed by more qualitative diagnosis, and optimization of the treatment strategy. In 2014, the International Thymic Malignancy Interest Group presented a new mediastinal clinical classification. In this classification, mediastinal masses are categorized into three groups according to location: prevascular (anterior)-, visceral (middle)-, and paravertebral (posterior)-compartment masses. Then, the internal characteristics and functional images are evaluated.
Differentiation of mediastinal masses is very difficult. However, if typical imaging findings and clinical characteristics are combined, reasonable differentiation is possible. In each patient, proper differential diagnosis may contribute to better treatment selection.
The Role of Extracorporeal Membrane Oxygenation in the Anesthetic Management of Superior Vena Cava Syndrome: Is it Time to Use a Scoring System?
2022, Journal of Cardiothoracic and Vascular Anesthesia

View all citing articles on Scopus

: The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or as representing the views of the Department of the Air Force or the Department of Defense.

View full text

Chest

reviewsPrimary Mediastinal Tumors. Part 1*: Tumors of the Anterior Mediastinum

Section snippets

Thymoma

Thymic Carcinoma

Thymic Carcinoid

Thymolipoma

Nonneoplastic Thymic Cysts

Mediastinal Germ Cell Tumors

Mediastinal Lymphangioma

Mediastinal Goiter

Mediastinal Parathyroid Adenoma

Conclusion

ACKNOWLEDGMENT

Chest

Ann Thorac Surg

Mayo Clin Proc

J Thorac Cardiovasc Surg

Ann Thorac Surg

Ann Thorac Surg

J Thorac Cardiovasc Surg

Chest

J Urol

J Thorac Cardiovasc Surg

Urology

Urology

J Pediatr Surg

J Thorac Cardiovasc Surg

Mayo Clin Proc

Otolaryngol Clin North Am

Semin Ultrasound CT MR

Surgical treatment of mediastinal tumors

J Thorac Cardiovasc Surg

The normal chest

Tumors of the thymus

Thymoma and other tumors of the thymus: an analysis of 107 cases

Cancer

Tumors of the anterior mediastinum

Cancer

Thymoma: a clinicopathologic review

Cancer

Thymoma—report of 71 cases and a review

Crit Rev Diagn Imaging

Thymomas: a review of 169 cases with particular reference to results of surgical treatment

Cancer

The spectrum of diseases associated with thymoma

Arch Intern Med

Studies in myasthenia gravis: review of a 20-year experience in over 1200 patients

Mt Sinai J Med

Auto antibodies to acetylcholine receptors in myasthenia gravis

N Engl J Med

Clinical correlation of antibodies that bind, block or modulate human acetylcholine receptors in myasthenia gravis

Ann NY Acad Sci

Post-thymectomy myasthenia gravis: report of a case of ocular myasthenia gravis after total removal of a thymoma and review of the literature

Neurology

Thymoma, hypogammaglobulinemia, and absence of eosinophils

J Clin Invest

Invasive thymomas: diagnosis and evaluation by CT

J Comput Assist Tomogr

Case report: intracaval and intracardiac extension of malignant thymoma: CT diagnosis

J Comput Assist Tomogr

Thymoma: radiologic-pathologic correlation

Radiographics

Thymomas presenting as pleural tumors

Am J Surg Pathol

Transdiaphragmatic extension of invasive thymoma

AJR Am J Roentgenol

reviews
Primary Mediastinal Tumors. Part 1*: Tumors of the Anterior Mediastinum