Second most common primary anterior mediastinal mass in adults. Most are seen in the anterior compartment and rest are seen in middle compartment. Hodgkin's usually present in 40-50's with nodular sclerosing type (7), and non-Hodgkin's in all age groups. Can also be primary mediastinal B-cell lymphoma with exceptionally good prognosis. Common symptoms include fever, weight loss, night sweats, and compressive symptoms such as pain, dyspnea, wheezing, Superior vena cava syndrome, pleural effusions (10,11). Diagnosis usually by CT showing lobulated mass. Confirmation done by tissue biopsy of accompanying nodes if any, mediastinoscopy, mediastinotomy, or thoracotomy. FNA biopsy is usually not adequate. (12,13,14) Treatment of mediastinal Hodgkin's involves chemotherapy and/or radiation. 5 year survival is now around 75%. (15) Large-cell type may have somewhat better prognosis. Surgery is generally not performed because of invasive nature of tumor.

Of all cancers involving the same class of blood cell, 2% of cases are mediastinal large B cell lymphomas.

Most common primary anterior mediastinal tumor (20%) in adults but rarely seen in children. It can be classified as lymphocytic, epithelial, or spindle cell histologies, but the clinical significance of these classifications is controversial. Tonofibrils seen under electron microscopy can differentiate thymoma from other tumors such as carcinoid, Hodgkin's, and seminoma. Patients are usually asymptomatic but can present with myasthenia gravis-related symptoms, substernal pain, dyspnea, or cough. Invasive tumors can produce compression effects such as superior vena cava syndrome. (3,4) Thymomas are diagnosed with CT or MRI revealing a mass in anterior mediastinum. Therapy in stage I tumors consists of surgical resection with good prognosis. Stage II-III requires maximal resection possible followed by radiation. Stage IV disease requires addition of cisplatin-based chemotherapy in addition to those in stage II and III. For those with invasive thymoma, treatment is based on induction chemotherapy, surgical resection, and post-surgical radiation. 5-year survival for invasive thymoma is between 12-54% regardless of any myasthenia gravis symptoms (5,6).

Most myelolipomas are unexpected findings on CT scans and MRI scans of the abdomen. They may sometimes be seen on a plain X-ray films.

Fine needle aspiration may be performed to obtain cells for microscopic diagnosis.

The most common way to test someone for PPB is to take a biopsy. Other tests like x-rays, CAT scans, and MRI's can suggest that cancer is present, but only an examination of a piece of the tumor can make a definite diagnosis.

A computed tomography (CT) scan is the definitive diagnostic imaging test.

X-ray of the neck often (80% of the time) shows swelling of the retropharyngeal space in affected individuals. If the retropharyngeal space is more than half of the size of the C2 vertebra, it may indicate retropharyngeal abscess.

Pleuropulmonary blastoma is classified into 3 types:

- Type I is multicystic

- Type II shows thickening areas (nodules) within this cystic lesion

- Type III shows solid masses.

Type I PPB is made up of mostly cysts, and may be hard to distinguish from benign lung cysts, and there is some evidence that not all type I PPB will progress to types II and III. Types II and III are aggressive, and cerebral metastasis is more frequent in PPB than in other childhood sarcomas.

Myelolipomas are usually found to occur alone in one adrenal gland, but not both. They can vary widely in size, from as small as a few millimetres to as large as 34 centimeters in diameter. The cut surface has colours varying from yellow to red to mahogany brown, depending on the distribution of fat, blood, and blood-forming cells. The cut surface of larger myelolipomas may contain haemorrhage or infarction.

Ganglioneuromas can be diagnosed visually by a CT scan, MRI scan, or an ultrasound of the head, abdomen, or pelvis. Blood and urine tests may be done to determine if the tumor is secreting hormones or other circulating chemicals. A biopsy of the tumor may be required to confirm the diagnosis.

The purpose of radiologic imaging is to locate the lesion, evaluate for signs of invasion and detect metastasis. Features of GIST vary depending on tumor size and organ of origin. The diameter can range from a few millimeters to more than 30 cm. Larger tumors usually cause symptoms in contrast to those found incidentally which tend to be smaller and have better prognosis. Large tumors tend to exhibit malignant behavior but small GISTs may also demonstrate clinically aggressive behavior.

Plain radiographs are not very helpful in the evaluation of GISTs. If an abnormality is seen, it will be an indirect sign due to the tumor mass effect on adjacent organs. On abdominal x-ray, stomach GISTs may appear as a radiopaque mass altering the shape of the gastric air shadow. Intestinal GISTs may displace loops of bowel and larger tumors may obstruct the bowel and films will show an obstructive pattern. If cavitations are present, plain radiographs will show collections of air within the tumor. Calcification is an unusual feature of GIST but if present can be visible on plain films.

Barium fluoroscopic examinations and CT are commonly used to evaluate the patient with abdominal complaints. Barium swallow images show abnormalities in 80% of GIST cases. However, some GISTs may be located entirely outside the lumen of the bowel and will not be appreciated with a barium swallow. Even in cases when the barium swallow is abnormal, an MRI or CT scan must follow since it is impossible to evaluate abdominal cavities and other abdominal organs with a barium swallow alone. In a CT scan, abnormalities may be seen in 87% of patients and it should be made with both oral and intravenous contrast. Among imaging studies, MRI has the best tissue contrast, which aids in the identification of masses within the GI tract (intramural masses). Intravenous contrast material is needed to evaluate lesion vascularity.

Preferred imaging modalities in the evaluation of GISTs are CT and MRI, and, in selected situations, endoscopic ultrasound. CT advantages include its ability to demonstrate evidence of nearby organ invasion, ascites, and metastases. The ability of MRI to produce images in multiple planes is helpful in determining the bowel as the organ of origin (which is difficult when the tumor is very large), facilitating diagnosis.

A chondroma is a benign cartilaginous tumor, which is encapsulated with a lobular growing pattern.

Tumor cells (chondrocytes, cartilaginous cells) resemble normal cells and produce the cartilaginous matrix (amorphous, basophilic material).

Characteristic features of this tumor include the vascular axes within the tumor, which make the distinction with normal hyaline cartilage.

Based upon location, a chondroma can be described as an enchondroma or ecchondroma.

- enchondroma - tumor grows within the bone and expands it.

- ecchondroma - grows outward from the bone and this is rare.

Treatment

- best left alone

- if it causes fractures (enchondroma) or is unsightly it should be removed by curettage and the defect filled with bone graft.

Although often described as benign, a teratoma does have malignant potential. In a UK study of 351 infants and children diagnosed with "benign" teratoma reported 227 with MT, 124 with IT. Five years after surgery, event-free survival was 92.2% and 85.9%, respectively, and overall survival was 99% and 95.1%. A similar study in Italy reported on 183 infants and children diagnosed with teratoma. At 10 years after surgery, event free and overall survival were 90.4% and 98%, respectively.

Depending on which tissue(s) it contains, a teratoma may secrete a variety of chemicals with systemic effects. Some teratomas secrete the "pregnancy hormone" human chorionic gonadotropin (βhCG), which can be used in clinical practice to monitor the successful treatment or relapse in patients with a known HCG-secreting teratoma. This hormone is not recommended as a diagnostic marker, because most teratomas do not secrete it. Some teratomas secrete thyroxine, in some cases to such a degree that it can lead to clinical hyperthyroidism in the patient. Of special concern is the secretion of alpha-fetoprotein (AFP); under some circumstances AFP can be used as a diagnostic marker specific for the presence of yolk sac cells within the teratoma. These cells can develop into a frankly malignant tumor known as yolk sac tumor or endodermal sinus tumor.

Adequate follow-up requires close observation, involving repeated physical examination, scanning (ultrasound, MRI, or CT), and measurement of AFP and/or βhCG.

Following diagnosis and histopathological analysis, the patient will usually undergo magnetic resonance imaging (MRI), ultrasonography, and a bone scan in order to determine the extent of local invasion and metastasis. Further investigational techniques may be necessary depending on tumor sites. A parameningeal presentation of RMS will often require a lumbar puncture to rule out metastasis to the meninges. A paratesticular presentation will often require an abdominal CT to rule out local lymph node involvement, and so on. Patient outcomes are most strongly tied to the extent of the disease, so it is important to map its presence in the body as soon as possible in order to decide on a treatment plan.

The current staging system for rhabdomyosarcoma is unusual relative to most cancers. It utilizes a modified TNM (tumor-nodes-metastasis) system originally developed by the IRSG. This system accounts for tumor size (> or <5 cm), lymph node involvement, tumor site, and presence of metastasis. It grades on a scale of 1 to 4 based on these criteria. In addition, patients are sorted by clinical group (from the clinical groups from the IRSG studies) based on the success of their first surgical resection. The current Children's Oncology Group protocols for the treatment of RMS categorize patients into one of four risk categories based on tumor grade and clinical group, and these risk categories have been shown to be highly predictive of outcome.

Since GISTs arise from the bowel layer called muscularis propria (which is deeper to the mucosa and submucosa from a luminal perspective), small GIST imaging usually suggest a submucosal process or a mass within the bowel wall. In barium swallow studies, these GISTs most commonly present with smooth borders forming right or obtuse angles with the nearby bowel wall, as seen with any other intramural mass. The mucosal surface is usually intact except for areas of ulceration, which are generally present in 50% of GISTs. Ulcerations fill with barium causing a bull's eye or target lesion appearance. In contrast-enhanced CT, small GISTs are seen as smooth, sharply defined intramural masses with homogeneous attenuation.

The diagnosis of a mediastinal germ cell tumor should be considered in all young males with a mediastinal mass. In addition to physical examination and routine laboratory studies, initial evaluation should include CT of the chest and abdomen, and determination of serum levels of HCG and alpha-fetoprotein.

Extraspinal ependymoma, usually considered to be a glioma (a type of non-germ cell tumor), may be an unusual form of mature teratoma.

The first step to diagnosing tonsil carcinoma is to obtain an accurate history from the patient. The physician will also examine the patient for any indicative physical signs. A few tests then, maybe conducted depending on the progress of the disease or if the doctor feels the need for. The tests include:

Fine needle aspiration, blood tests, MRI, x-rays and PET scan.

The basis of deciding the T stage depends on physical examination and imaging of the tumor.

RPA's frequently require surgical intervention. A tonsillectomy approach is typically used to access/drain the abscess, and the outcome is usually positive. Surgery in adults may be done without general anesthesia because there is a risk of abscess rupture during tracheal intubation. This could result in pus from the abscess aspirated into the lungs. In complex cases, an emergency tracheotomy may be required to prevent upper airway obstruction caused by edema in the neck.

High-dose intravenous antibiotics are required in order to control the infection and reduce the size of the abscess prior to surgery.

Chronic retropharyngeal abscess is usually secondary to tuberculosis and the patient needs to be started on anti-tubercular therapy as soon as possible.

Rhabdomyosarcoma is often difficult to diagnose due to its similarities to other cancers and varying levels of differentiation. It is loosely classified as one of the “small, round, blue-cell cancer of childhood” due to its appearance on an H&E stain. Other cancers that share this classification include neuroblastoma, Ewing sarcoma, and lymphoma, and a diagnosis of RMS requires confident elimination of these morphologically similar diseases. The defining diagnostic trait for RMS is confirmation of malignant skeletal muscle differentiation with myogenesis (presenting as a plump, pink cytoplasm) under light microscopy. Cross striations may or may not be present. Accurate diagnosis is usually accomplished through immunohistochemical staining for muscle-specific proteins such as myogenin, muscle-specific actin, desmin, D-myosin, and myoD1. Myogenin, in particular, has been shown to be highly specific to RMS, although the diagnostic significance of each protein marker may vary depending on the type and location of the malignant cells. The alveolar type of RMS tends to have stronger muscle-specific protein staining. Electron microscopy may also aid in diagnosis, with the presence of actin and myosin or Z bands pointing to a positive diagnosis of RMS. Classification into types and subtypes is accomplished through further analysis of cellular morphology (alveolar spacings, presence of cambium layer, aneuploidy, etc.) as well as genetic sequencing of tumor cells. Some genetic markers, such as the "PAX3-FKHR" fusion gene expression in alveolar RMS, can aid in diagnosis. Open biopsy is usually required to obtain sufficient tissue for accurate diagnosis. All findings must be considered in context, as no one trait is a definitive indicator for RMS.

Most ganglioneuromas are noncancerous, thus expected outcome is usually good. However, a ganglioneuroma may become cancerous and spread to other areas, or it may regrow after removal.

If the tumor has been present for a long time and has pressed on the spinal cord or caused other symptoms, it may have caused irreversible damage that cannot be corrected with the surgical removal of the tumor. Compression of the spinal cord may result in paralysis, especially if the cause is not detected promptly.

The high-resolution computed tomography (HRCT) chest scan is better than the chest radiograph to detect cystic parenchymal disease and is almost always abnormal at the time of diagnosis, even when the chest radiograph and pulmonary function assessments are normal. The typical CT shows diffuse round, bilateral, thin-walled cysts of varying sizes ranging from 1 to 45 mm in diameter. The numbers of cysts varies in LAM from a few to almost complete replacement of normal lung tissue. The profusion of cysts tends to be milder in patients with TSC-LAM than S-LAM, perhaps explained in part because TSC-LAM patients typically receive earlier screening. Pleural effusions are seen on CT in 12% of patients with S-LAM and 6% of patients with TSC-LAM. Other CT features include linear densities (29%), hilar or mediastinal lymphadenopathy (9%), pneumothorax, lymphangiomyoma, and thoracic duct dilation. Ground-glass opacities (12%) suggest the presence of interstitial edema due to lymphatic congestion. In patients with TSC, nodular densities on HRCT may represent multifocal micronodular pneumocyte hyperplasia (MMPH) made up of clusters of hyperplastic type II pneumocytes. MMPH may be present in males or females with TSC in the presence or absence of LAM, but not in patients with S-LAM. MMPH is not typically associated with physiologic or prognostic consequences, but one case of respiratory failure due to MMPH has been reported.

The chest radiograph may appear relatively normal, even late in the disease, or may suggest hyperinflation only. As the disease progresses, the chest radiograph often demonstrates diffuse, bilateral and symmetric reticulonodular opacities, cysts, bullae or a "honeycomb" (i.e., pseudo fibrotic) appearance. Pleural effusion and pneumothorax may be apparent. Preservation of lung volumes in the presence of increased interstitial markings is a radiographic hallmark of LAM that helps distinguish it from most other interstitial lung diseases, in which alveolar septal and interstitial expansion tend to increase the lung’s elastic recoil properties and decreased lung volumes.

Hyperparathyroidism is confirmed by blood tests such as calcium and PTH levels. A specific test for parathyroid adenoma is sestamibi parathyroid scintigraphy, the sestamibi scan. This nuclear imaging technique reveals the presence and location of pathological parathyroid tissue.

An ecchondroma is a type of chondroma that is subperiosteal. A proliferation is known as "ecchondrosis".

Malignant germ cell tumors of the mediastinum are uncommon, representing only 3 to 10% of tumors originating in the mediastinum. They are much less common than germ cell tumors arising in the testes, and account for only 1 to 5% of all germ cell neoplasms.

Syndromes associated with mediastinal germ cell tumors include Hematologic Neoplasia and Klinefelter's syndrome.