Primary mediastinal tumors. Part 1: tumors of the anterior mediastinum

Surgical treatment of thymoma

PURPOSE

A case report is presented of a 66-year-old white woman with a 3-month history of atypical chest pain and shortness of breath.

METHODS

A lateral chest radiograph demonstrated an anterior mediastinal density. A subsequent computed tomography (CT) scan revealed a mass in the right anterolateral mediastinum. Fine-needle aspiration (FNA) revealed tumor cells positive for cytokeratin and negative for leukocyte common antigen.

RESULTS

The differential diagnosis at that time included thymoma versus thymic carcinoid. She underwent a median sternotomy with complete thymectomy. The pathology revealed a large thymoma with microinvasion into the surrounding adipose tissue. She had an uneventful postoperative course and later underwent adjuvant radiation therapy.

CONCLUSIONS

Surgical treatment of thymoma is discussed, with emphasis on diagnosis and treatment. Although some patients may present with symptoms caused by involvement of surrounding structures, most thymomas are discovered incidentally on chest radiograph. Various diagnostic procedures can aid the surgeon in ruling out other neoplasms, such as lymphoma or germ cell tumors. Prognosis is not based on histology, but on the tumor's gross characteristics at operation. Benign tumors are noninvasive and encapsulated. All patients with potentially resectable lesions should undergo en-bloc excision. Radiation or chemotherapy should be instituted in more advanced tumors.

Tuberculosis of the thymus

Tumors of the anterior mediastinum include several entities with different radiological and clinical manifestations, constituting a heterogeneous group of congenital, inflammatory, and neoplastic conditions. Among these lesions, the most common primary tumor of the mediastinum is thymoma, nearly followed by germ cell tumors and lymphomas. Tuberculosis of the thymus, an extremely rare condition, typically involves the mediastinal lymph nodes. We present, in this study, pathological, radiological, and clinical findings of one case of tuberculosis of the thymus in an 18-year-old patient who presented thoracic pain, dyspnea upon minimal effort, and progressive worsening of the symptoms in one week. The chest X-ray showed a large mass in the mediastinum, and computed tomography scans indicated that it was located anteriorly. The patient was submitted to surgery in order to excise the mass. Microscopy revealed a massive inflammatory response and granulomas in the thymic tissue. Ziehl-Neelsen staining for acid-fast bacilli yielded positive results, and a diagnosis of tuberculosis was made. Surgeons and pathologists should remain alert for this condition and should include it in the differential diagnosis of mediastinal masses.

MR imaging of the chest: A practical approach at 1.5T

Magnetic resonance imaging (MRI) is capable of imaging infiltrative lung diseases as well as solid lung pathologies with high sensitivity. The broad use of lung MRI was limited by the long study time as well as its sensitivity to motion and susceptibility artifacts. These disadvantages were overcome by the utilisation of new techniques such as parallel imaging. This article aims to propose a standard MR imaging protocol at 1.5T and presents a spectrum of indications. The standard protocol comprises non-contrast-enhanced sequences. Following a GRE localizer (2D-FLASH), a coronal T2w single-shot half-Fourier TSE (HASTE) sequence with a high sensitivity for infiltrates and a transversal T1w 3D-GRE (VIBE) sequence with a high sensitivity for small lesions are acquired in a single breath hold. Afterwards, a coronal steady-state free precession sequence (TrueFISP) in free breathing is obtained. This sequence has a high sensitivity for central pulmonary embolism. Distinct cardiac dysfunctions as well as an impairment of the breathing mechanism are visible. The last step of the basic protocol is a transversal T2w-STIR (T2-TIRM) in a multi-breath holds technique to visualize enlarged lymph nodes as well as skeletal lesions. The in-room time is approximately 15min. The extended protocol comprises contrast-enhanced sequences (3D-GRE sequence (VIBE) after contrast media; about five additional minutes). Indications are tumorous lesions, unclear (malignant) pleural effusions and inflammatory diseases (vaskulitis). A perfusion analysis can be achieved using a 3D-GRE in shared echo-technique (TREAT) with a high temporal resolution. This protocol can be completed using a MR-angiography (3D-FLASH) with high spatial resolution. The in-room time for the complete protocol is approximately 30min.

Mucinous adenocarcinomas of the thymus: report of 2 cases and review of the literature

BACKGROUND

Most adenocarcinomas of the mediastinum are metastatic lesions. Primary thymic adenocarcinomas are extremely rare neoplasms. We could find only 12 cases reported in the literature; of these 12, only 4 were of the mucinous subtype.

DESIGN

We report 2 additional cases of the mucinous subtype, including a previously unreported mucinous variant with numerous psammoma bodies.

RESULTS

The first case in a 61-year-old woman resembled a mucinous (colloid) carcinoma of other organs such as the breast and colon. It consisted of islands and strips of tumor cells floating in large pools of extracellular mucin. A unique feature of this tumor was the presence of numerous psammoma bodies. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) 7 and negative for CD5. The second case in an 82-year-old woman was a mucinous adenocarcinoma arising from a thymic cyst with areas of transition from benign to dysplastic epithelium. The tumor cells formed dilated glands, cords, and small nests that infiltrated the thymic cyst wall and exhibited evidence of mucin production. Immunohistochemically, the tumor cells were positive for CK 7 and focally positive for both CD5 and CK 5/6.

CONCLUSIONS

Mucinous adenocarcinoma, with or without, psammoma bodies, may be of primary thymic origin and should be considered in the differential diagnosis of malignant mediastinal tumors. These 2 cases provide further documentation of the rare occurrence of primary mucinous adenocarcinomas of the thymic gland.

Immunological system status and the appearance of respiratory system disturbances in thymectomized patients

Introduction

Adult-onset thymoma may be responsible for several diseases, such as pure red cell aplasia, myasthenia gravis, and immunodeficiency (Good’s syndrome). Thymectomy does not always improve the patient’s condition, and may even produce additional symptoms. Its pathogenesis is still not entirely understood, but autoimmunological processes and bone marrow defect are the most frequently suggested.

Materials and Methods

Eleven patients (mean age: 56.2 ± 15.5 years) were analyzed 6 months to 10 years after thymectomy due to thymoma as were 25 healthy persons serving as controls. Enzyme-linked immunosorbent assay (ELISA) and flow cytometry techniques were used to evaluate the immunological status of the subjects.

Results

Good’s syndrome was diagnosed in one patient, 4 subjects suffered from myasthenia gravis, and recurrent infections of upper and lower respiratory tract appeared in 9 patients. The immunological analyses (ELISA and flow cytometry) revealed a significantly lower IgG level (p < 0.05), percentage of peripheral blood B lymphocytes (p < 0.0005), and CD4:CD8 ratio (p < 0.05) in thymectomized patients compared with the healthy controls. The percentages of CD4⁺ and CD8⁺ T lymphocytes expressing CD28 antigen were significantly lower in thymectomized patients than in healthy subjects (p < 0.005 and p < 0.01, respectively). The percentage of naïve T helper lymphocytes was significantly lower in the patients than in the control group (p < 0.05).

Conclusions

Immunodeficiency and recurrent infections may be the first symptoms of immunological disturbances after thymectomy in adults. It is suggested that regular medical monitoring of these patients is important in preventing further complications, which may result in irreversible lung tissue destruction.

Mediastinal, cystic and functional parathyroid adenoma in patients with double parathyroid adenomas: a case report

Primary hyperparathyroidism is usually caused by single adenoma. Ectopic adenomas are a frequent cause of recurrent or persistent hyperparathyroidism. Parathyroid cysts are rarely seen and most of them are non functional. This case report describes a patient with double adenoma, one is solid and cervical, the other is cystic and located in mediastinum; both of them are functional.

Primary Solitary Mediastinal Mass Lesions: A Review of 37 Cases

BACKGROUND

Primary solitary mass lesions of the mediastinum, although relatively uncommon, encompass an interesting spectrum of pathologies.

METHODS

A comprehensive retrospective review was undertaken of all cases of mediastinal lesions that presented to the two major thoracic surgical centres in North Queensland, Australia, over a 7-year period.

RESULTS

Thirty-seven mediastinal mass lesions were managed over the period of the review. Over one-quarter of all cases were clinically silent, the pathology having been discovered incidentally during investigation for other reasons. Malignant thymoma was the single most common pathology, being present in 13 (35.1%) cases. A variety of other pathologies were encountered, including thymic cyst, bronchogenic cyst, neurofibroma, parathyroid adenoma, and lymphoma. Expeditious surgical resection of the lesions, once discovered, afforded good medium-term survival, even for those patients with malignant pathology.

CONCLUSIONS

Prompt thoracic surgical referral with view to aggressive, early resection optimizes clinical outcome in the short and medium-term for patients presenting with mass lesions of the mediastinum.

Expression of OCT4 in the Primary Germ Cell Tumors and Thymoma in the Mediastinum

Primary germ cell tumors (GCTs) and thymoma are both located in the anterior mediastinum. A previous study has postulated that octamer binding transcription factor (OCT4) is a nuclear transcription factor that is expressed in pluripotent embryonic germ cells. This study examined OCT4 expression in GCTs and thymoma originating from the mediastinum. A retrospective study included 46 consecutive patients with GCTs conducted between 1983 and 2005, and 22 consecutive thymoma in the mediastinum whose tumors had been surgically excised. The 46 primary GCTs in mediastinum included teratoma (n=27; 58.7%), seminoma (n=10; 21.7%), yolk sac tumor (n=6; 13%), embryonal carcinoma (n=1; 2.1%), and mixed GCTs (n=2; 4%; one consisted of teratoma and yolk sac tumor, and the other teratoma, yolk sac tumor, and seminoma); and 22 thymoma including World Health Organization type A (n=3, 13.6%), type AB (n=4, 18.2%), type B1 (n=6, 27.3%), type B2 (n=4, 13.6%), and type B3 (n=5, 22.7%). Each tumor was examined with hematoxylin and eosin staining, and with antibodies to OCT4. All 10 seminoma cases, 1 embryonal carcinoma case, and 1 mixed GCT case containing seminoma were immunopositive for OCT4. On the other hand, the 22 thymoma, 6 yolk sac tumor, 27 teratomas, and 1 case with mixed GCT without component of seminoma were immunonegative for OCT4. We conclude that immunostaining with antibodies to OCT4 is a useful diagnostic tool in the identification of seminomas and primary embryonal carcinomas in GCTs originating from the mediastinum.

The Role of Radiation Therapy in Thoracic Tumors

Radiation plays an important role in the treatment of thoracic tumors. During the last 10 years there have been several major advances in thoracic RT including the incorporation of concurrent chemotherapy and the application of con-formal radiation-delivery techniques (eg, stereotactic RT, three-dimensional conformal RT, and intensity-modulated RT) that allow radiation dose escalation. Radiation as a local measure remains the definitive treatment of medically inoperable or surgically unresectable disease in NSCLC and part of a multimodality regimen for locally advanced NSCLC, limited stage SCLC, esophageal cancer, thymoma, and mesothelioma.

Imaging of thymic disorders

Evaluation of the thymus poses a challenge to the radiologist. In addition to age-related changes in thymic size, shape, and tissue composition, there is considerable variability in the normal adult thymic appearance within any age group. Many different types of disorders may affect the thymus, including hyperplasia, cysts, and benign and malignant neoplasms, both primary and secondary; clinical and imaging findings typical for each disease process are described in this article. Whereas computed tomography is the mainstay for imaging the thymus, other imaging modalities may occasionally provide additional structural or functional information.

Tumors of the mediastinum

Tumors of the mediastinum represent a wide diversity of disease states. The location and composition of a mass is critical to narrowing the differential diagnosis. The most common causes of an anterior mediastinal mass include the following: thymoma; teratoma; thyroid disease; and lymphoma. Masses of the middle mediastinum are typically congenital cysts, including foregut and pericardial cysts, while those that arise in the posterior mediastinum are often neurogenic tumors. The clinical sequelae of mediastinal masses can range from being asymptomatic to producing symptoms of cough, chest pain, and dyspnea. This article will review the anatomy of the mediastinum as well as the different clinical, radiographic, and prognostic features, and therapeutic options of the most commonly encountered masses.

Thymic carcinoma originating from the mid-posterior mediastinum

An unusual thymic carcinoma in a 74-year-old woman is described. Initial chest CT revealed a mass at the mid-posterior mediastinum. Transbronchial fine needle biopsy of the mass failed to provide a definite diagnosis. The mass was treated as a malignant mediastinal tumour, and chemoradiotherapy was performed as initial treatment. The patient died 5 years after receiving primary treatment. The results of postmortem microscopic examination, including immunohistochemical study with CD5 antibody, were consistent with thymic carcinoma. This case is interesting in that the mid-posterior mediastinum is the site where thymic carcinoma is least likely to originate.

[69 year-old patient with opaque hemithorax on the right side]

Liposarcomas are the most common sarcomas in adults. Mediastinal occurrence is very rare. We report on a 69 year-old man with a huge tumor in the right pleural cavity leading to a complete atelectasis of the right lung. The tumor could be completely resected. Histology showed a well-differentiated liposarcoma of the mediastinum. One year after resection there was no evidence for local recurrence or metastatic spread.

Primary Germ Cell Tumors of the Mediastinum: 10 Years of Experience in a Tertiary Teaching Hospital

Germ cell tumors occur mostly in the gonad. Extragonadal germ cell tumors are rare, and most occur in the retroperitoneum and mediastinum. Primary mediastinal germ cell tumors are often found in the anterior portion of the mediastinum and include teratomas and non-teratomatous tumors. Non-teratomatous tumors include seminomas and malignant non-seminomatous germ cell tumors (MNSGCTs). MNSGCTs include yolk sac tumors, choriocarcinomas, embryonal carcinomas, and mixed type germ cell tumors. Teratomas are the most common germ cell tumors of the mediastinum, and seminomas are the most common non-teratomatous germ cell tumors of the mediastinum. Cases of primary mediastinal MNSGCT reported in the literature are rare. In this report, we review all primary mediastinal germ cell tumors from a 10-year period at the Chung-Ho Memorial Hospital of Kaohsiung Medical University. A total of 14 cases were reviewed, including 11 patients with mature teratomas, two with yolk sac tumors, and one with seminoma. We discuss the differences in clinical presentation, histopathologic characteristics, treatment, and prognosis.

[Cystic lesion of the dorsal mediastinum]

We present the case of a 52-year-old male who underwent thoracotomy for resection of a suspected bronchogenic cyst in the right posterior mediastinum. The size of the tumor had increased over years, according to repeated X-rays, and the cyst became symptomatic with obstruction of the right subclavian and jugular veins. To our surprise, histopathology revealed a hydatid cyst.

Anterior mediastinal nonseminomatous germ cell tumor with malignant transformation: a case report

OBJECTIVE

We report a case of a 21-year-old man who presented with the unusual symptoms of heart failure and was found to have an anterior mediastinal yolk sac tumor.

METHODS

A review of the literature using the Ovid search engine was performed.

RESULTS

The patient was treated with the current standard of neoadjuvant chemotherapy: bleomycin, etoposide, and cisplatin (BEP) with marked reduction in tumor size, followed by en bloc surgical resection. The final pathology revealed teratoma with malignant change: chondrosarcoma, adenocarcinoma, and poorly differentiated sarcoma.

CONCLUSIONS

This is a rare initial presentation of an anterior mediastinal germ-cell tumor with treatment consisting of neoadjuvant therapy and surgical resection. In addition, we present the adverse and extremely rare malignant degeneration of this tumor.

Imaging findings of expansile lesions of the thymus

The purpose of this article is to review the imaging findings of the different expansile lesions of the thymus. Almost 50% of all mediastinal masses are located in the anterior mediastinum. The thymus is the most common site of origin of these masses. Several kinds of lesions can arise from this gland because it derives from the three embryonic germ cell layers. Primary neoplasms of the thymus are thymoma, thymolipomas, carcinoma, carcinoid, primary germ cell tumors, and lymphoma. The latter can also involve the organ in a secondary fashion. Other lesions that cause thymic enlargement and that can be confused with neoplasia are thymic cysts and thymic hyperplasia. Even though anterior mediastinal masses are first found on conventional radiographs, computed tomography and magnetic resonance are very useful additional studies for assessing the origin and extension of these masses. The basic concepts regarding embryology, anatomy, and histology relevant for the differential diagnosis of an enlarged thymic gland are also described.

Imaging of thymoma

Thymomas are the most common mediastinal tumors, usually diagnosed initially by CT. CT scanning can aid in characterization of thymoma and can successfully distinguish thymomas from other benign mediastinal tumors and from lymphoma. However, many of the primary mediastinal masses demonstrate overlap between imaging features and frequently resection is advisable for definitive characterization.

Imaging Evaluation of Pediatric Mediastinal Masses

Mediastinal masses in children are a heterogeneous group of asymptomatic to potentially life-threatening congenital, infectious, or neoplastic lesions that can present complex diagnostic and therapeutic dilemmas. This article presents the imaging features of the common mediastinal masses seen in the pediatric population. Classification of the masses is performed according to the traditional mediastinal compartment model, consisting of the anterior, middle, and posterior mediastinum. This scheme facilitates differentiation of the variety of disorders.

Mucoepidermoid carcinoma of the thymus: a case report

Mucoepidermoid carcinoma of the thymus is an extremely rare malignant mediastinal neoplasm, and to our knowledge, only 13 cases have been reported. We report a case of mucoepidermoid carcinoma of the thymus that was seen in a 53-yr-old man with right chest pain. Chest CT scan showed a huge, cystic mass having a focal solid portion with direct invasion of the adjacent anterior chest wall and pericardium in the anterior mediastinum. Mucoepidermoid carcinoma of the thymus should be included in the differential diagnosis for masses of the anterior mediastinum associated with extensive cystic changes, although the carcinoma is exceedingly rare.

Familial thymic cyst

Thymic cysts are rare lesions of the anterior mediastinum or neck. The majority are asymptomatic, and the remainder are associated mainly with symptoms of dysphagia or dyspnea. Diagnosis is difficult before surgery. Cervical thymic cysts are relatively rare; age at presentation ranges from the neonatal period to adulthood, and the most frequent presenting sign is a lateral neck mass. Mediastinal thymic cysts are more common and account for 1% of all mediastinal masses. They tend to occur in the older age group and are usually detected incidentally on chest X-ray film or computed tomography scans. Dysphagia and dyspnea are the main symptoms. We describe two brothers, aged 5 and 8 years, with mediastinal thymic cysts that presented as low cervical masses and review the embryology, diagnosis and management of thymic cysts.

Uncommon primary mediastinal tumours

The mediastinum is a unique anatomic area containing several structures and pluripotent cells that allow for the development of a range of tumours. Uncommon neoplasms of the mediastinum account for less than 10% of all mediastinal masses and include primary thymic carcinomas, neuroendocrine carcinomas, germ-cell tumours (GCTs), lymphomas, and neurogenic, endocrine, and mesenchymal tumours. Primary thymic carcinomas and neuroendocrine carcinomas, although rare, are highly malignant lesions. GCTs are thought to derive from primitive germ cells and can be classified in seminomatous and non-seminomatous GCTs. They are located predominantly in the anterior mediastinum, as are the primary mediastinal lymphomas that include Hodgkin lymphoma, large B cell lymphoma, and lymphoblastic lymphoma. Neurogenic tumours may arise from peripheral nerves, sympathetic ganglia, or rarely parasympathetic ganglia and are located predominantly in the posterior mediastinum. Endocrine tumours are the ectopic thyroid and parathyroid tumours. Mesenchymal tumours are rare tumours and no less problematic than they are in peripheral sites. The clinical, radiological, and therapeutic aspects of these tumours are reviewed.

Secondary malignant transformation of a primary mediastinal germ cell tumor with diffuse lymphangitic spread to the lungs

A 27-year-old man with no history of cardiopulmonary disease presented with progressive shortness of breath. He was significantly tachypneic and hypoxic, with inspiratory and expiratory wheezing. Evaluation of the chest with computed tomography revealed a large anterior mediastinal mass and interstitial thickening consistent with lymphangitic spread. Plasma beta-human chorionic gonadotropin level was elevated. Bronchoscopic biopsy specimen showed poorly differentiated carcinoma. Pleural fluid obtained via thoracentesis was positive for malignancy. Chemotherapy for the germ cell tumor, consisting of etoposide, ifosfamide, and cisplatin, resulted in dramatic clinical improvement and normalization of the beta-human chorionic gonadotropin level. The lymphangitic changes resolved, although the mediastinal mass persisted. A large, anterior mediastinal, mature teratoma, as well as pleural nodules with adenocarcinoma, was excised after completion of chemotherapy.

Mediastinal metastases from testicular nonseminomatous germ cell tumors: patterns of dissemination and predictors of long-term survival with surgery

OBJECTIVES

The purpose of this study was to determine the pattern of mediastinal dissemination of nonseminomatous germ cell tumors of testicular origin and evaluate variables that may influence survival with mediastinal dissection in patients with metastatic nonseminomatous germ cell tumors.

METHODS

From 1981 to 2000, a total of 421 patients were seen at our institution for extirpation of residual lung or mediastinal disease after cisplatin-based chemotherapy for metastatic testicular nonseminomatous germ cell tumors. We reviewed 268 of these patients, with a mean age of 26.8 years, who required at least one surgical procedure to remove residual mediastinal disease. Pathologic types of resected residual mediastinal disease were necrosis (15%), teratoma (59%), persistent nonseminomatous germ cell cancer (15%), and non-germ cell carcinomatous degeneration (11%). Twelve variables were evaluated by univariate analyses, and four variables potentially statistically significant at P <.10 were subsequently entered into a Cox regression model.

RESULTS

All patients demonstrated metastases to the visceral mediastinum. Fewer patients also demonstrated metastases to the paravertebral sulcus or anterior compartments (16% and 7%, respectively). Overall 5- and 10-year survivals were 86% +/- 2% and 74% +/- 4%, respectively. According to multivariate analysis, disease-related survival was negatively influenced by an elevated preoperative beta-human chorionic gonadotropin level (P =.028) and adverse pathologic characteristics of residual mediastinal disease (P =.006).

CONCLUSIONS

Testicular nonseminomatous germ cell tumors follow a predictable pattern of mediastinal dissemination, primarily following the course of the thoracic duct and its major tributaries. Patients who require surgery to remove residual mediastinal disease after cisplatin-based chemotherapy for metastatic nonseminomatous germ cell tumors have good to excellent long-term survivals. These results justify an aggressive surgical approach, including multiple surgical procedures if clinically indicated.

Surgical techniques for testicular nonseminomatous germ cell tumors metastatic to the mediastinum

Since 1980, the author and his colleagues have performed over 400 thoracic surgical procedures to remove residual mediastinal disease after cisplatin-based chemotherapy in nearly 300 patients with testicular nonseminomatous germ cell tumors [6]. Presurgical planning is individualized and may require coordination with urologic and head and neck surgeons to minimize the overall number of surgical procedures while maximizing exposure. Careful and systematic dissection can remove teratomatous residual disease from major blood vessels and intrathoracic nerves with minimal morbidity. The operative mortality rate has been low (1%), which is not unexpected in these otherwise young and healthy patients. The 10-year survival rate has been 78% from the time of diagnosis with removal of benign residual mediastinal disease pathologically consisting of either necrosis or teratoma. This success justifies an aggressive thoracic surgical approach in these cases. Commonly, multiple surgical procedures are required to remove bilateral or multiple levels of residual mediastinal disease or disease that presents during long-term follow-up. Prolonged survival seems possible following the resection of limited areas of persistent nonseminomatous germ cell tumors or nonseminomatous germ cell tumor degeneration into non-germ cell cancer within the mediastinum. Salvage surgery to remove chemotherapy-refractory mediastinal disease represents a situation in which significantly poorer long-term survival is anticipated; however, an aggressive surgical approach is justified in select patients.

The retrotracheal space: normal anatomic and pathologic appearances

A variety of diseases can arise from the normal contents of the retrotracheal space or from adjacent structures. Mediastinal diseases in the retrotracheal space typically manifest radiographically as a contour abnormality or an area of increased opacity, although computed tomography (CT) or magnetic resonance (MR) imaging is usually required for diagnosis. The most common aortic arch anomaly, a right subclavian artery that originates from an otherwise normal left-sided aortic arch, appears at posteroanterior chest radiography as an obliquely oriented soft-tissue area of increased opacity that extends superiorly to the right from the superior margin of the aortic arch. CT and MR imaging can reveal associated vascular or mediastinal abnormalities. Aortic aneurysms and pseudoaneurysms can manifest radiographically as fusiform or saccular masslike lesions that protrude into the retrotracheal space. Thoracic MR imaging and spiral CT angiography are the diagnostic procedures of choice for evaluating diverse pathologic conditions of the thoracic aorta. Esophageal diseases can manifest as an abnormality in the retrotracheal space, which may be the initial clue to the diagnosis. At CT, lymphatic malformations in the mediastinum manifest as lobular, multicystic tumors that surround and infiltrate adjacent mediastinal structures. Familiarity with the normal radiologic appearance of the retrotracheal space and with the clinical manifestations of diseases that affect the retrotracheal space and adjacent structures can facilitate detection, diagnosis, and management.

Imaging of cystic masses of the mediastinum

Cystic masses of the mediastinum are well-marginated round lesions that contain fluid and are lined with epithelium. Major cystic masses include congenital benign cysts (ie, bronchogenic, esophageal duplication, neurenteric, pericardial, and thymic cysts), meningocele, mature cystic teratoma, and lymphangioma. Many tumors (eg, thymomas, Hodgkin disease, germ cell tumors, mediastinal carcinomas, metastases to lymph nodes, nerve root tumors) can undergo cystic degeneration-especially after radiation therapy or chemotherapy-and demonstrate mixed solid and cystic elements at computed tomography (CT) or magnetic resonance (MR) imaging. If degeneration is extensive, such tumors may be virtually indistinguishable from congenital cysts. A mediastinal abscess or pancreatic pseudocyst also appears as a fluid-containing mediastinal cystic mass. However, clinical history and manifestations, anatomic position, and certain details seen at CT or MR imaging allow correct diagnosis in many cases. Familiarity with the radiologic features of mediastinal cystic masses facilitates accurate diagnosis, differentiation from other cystlike lesions, and, thus, optimal patient treatment.

Airway obstruction complicating mediastinal tuberculosis: a life-threatening presentation

We discuss the case of a young man with mediastinal tuberculosis who presented with pericarditis, thymic involvement, and respiratory failure because of upper airway obstruction. Although mediastinal tuberculosis is not uncommon, the simultaneous occurrence of these complications is exceedingly rare and in this patient resulted in an acute life-threatening illness. The diagnosis and treatment of this condition can be complex, and these aspects of the patient's care are discussed.

Three-color flow cytometric study on lymphocytes derived from thymic diseases

BACKGROUND

Anterior mediastinal masses derive from a variety of diseases. Thymomas have been shown to commonly hold CD4(+)CD8(+) double-positive (DP) lymphocytes, and identification of this subset by two-color flow cytometric study was suggested to help diagnosis of thymoma. Several other thymic diseases, however, possibly hold CD4(+)CD8(+) DP lymphocytes. In this study, we utilized the three-color flow cytometric method for further examination of the phenotypes of lymphocytes in the thymic diseases.

MATERIALS AND METHODS

One hundred eight specimens (77 primary and 10 metastatic thymomas, 10 thymic carcinomas, 2 thymic carcinoids, 4 malignant lymphomas, 2 seminomas, an inflammatory pseudotumor, and 2 nonneoplastic thymic hyperplasias) were subjected to the study. The expressions of CD3, CD4, and CD8 on tumor-associated lymphocytes were evaluated by three-color flow cytometric study.

RESULTS

The proportion of the CD4(+)CD8(+) DP subset was more than 30% in all 78 lymphocyte-rich thymomas, in 2 malignant lymphomas, and in both thymic hyperplasias. CD3 expression of the CD4(+)CD8(+) DP subset ranged from a negative to a high level in thymomas and thymic hyperplasias, while it was restricted to a particular level in CD4(+)CD8(+) DP-type malignant lymphomas. The proportion of CD3(+) cells in the CD4(+)CD8(-) single-positive subset was consistently less than 90% in the lymphocyte-rich thymomas, while it was more than 90% in the thymic hyperplasias.

CONCLUSION

Although identification of the CD4(+)CD8(+) DP subset in the tumor-associated lymphocytes does not necessarily indicate thymoma, a further characterization of thymic neoplasms possessing the CD4(+)CD8(+) DP subset was enabled by three-color flow cytometric study, suggesting the utility of this method as an ancillary tool for differential diagnosis of these diseases.

Mediastinal tumors

Mediastinal tumors are comprised of various benign and malignant neoplasms that share the same anatomic location within the thorax. The mediastinum is traditionally divided into three compartments: the anterior, middle, and posterior mediastinum. This division, based on lateral chest radiographs, helps clinicians establish appropriate differential diagnoses and plan further imaging, diagnostic, and treatment strategies. With the continued and complex advances in imaging, medical treatment, and surgery, we recommend a multidisciplinary approach to the management of mediastinal tumors. This discussion is intended to guide the pulmonary specialist through this potentially complex approach.

[Primitive seminoma of the mediastinum: a case report]

In this study, the case has been reported of a 36-year old male who was treated at the Ibn Rochd Oncology Center in Casablanca for a primary mediastinal seminoma revealed by a symptomatology including cough, dyspnea, laterocervical swelling, rachidial pain and gait disorder. The preliminary investigation showed significant mediastinal enlargement with a right pleuritis and vertebral metastases; tumor markers were normal. The diagnosis of seminoma was confirmed by pathological and immunohistochemical analysis of the cervical adenopathy. Disease management consisted of BEP/cisplatin type chemotherapy and lumbar, mediastinal, and supraclavicular radiotherapy. The response after four courses of combined chemo-/radiotherapy was estimated at 25%, but the patient died from respiratory failure five months after the initiation of treatment.

Mediastinal germ cell tumors

Mediastinal germ cell tumors are uncommon tumors that occur predominantly within the anterior mediastinum and frequently present as a very large mass with local compression. Symptoms are typically vague and represent the local mass effects of the tumor. Chest computed tomography and examination of serum tumor markers provide the critical workup before a tissue diagnosis is obtained. Seminomas are extremely sensitive to both chemotherapy and radiation and are primarily treated nonsurgically. Benign teratomas without malignant elements are extremely resistant to both chemotherapy and radiation and are treated exclusively with surgical resection with excellent outcomes. Malignant nonseminomatous germ cell tumors are primarily treated with chemotherapy, with adjuvant surgery reserved for patients with residual mediastinal masses after systemic therapy.

Advanced heart block as a manifestation of a paraneoplastic syndrome from malignant thymoma

Malignant thymoma is a rare tumor that is associated with paraneoplastic syndrome. Myocarditis as a paraneoplastic syndrome has been rarely described. Reported herein is a young male patient with malignant thymoma and myocarditis as part of a paraneoplastic syndrome. This resulted in high-degree heart block and an asystolic cardiac arrest despite placement of a permanent pacemaker.