What are the other Names for this Condition? (Also known as/Synonyms)

• Inflammatory Pseudotumor of Mediastinum
• Mediastinal Inflammatory Fibrosarcoma
• Plasma Cell Granuloma of Mediastinum

What is Inflammatory Myofibroblastic Tumor of Mediastinum? (Definition/Background Information)

• Inflammatory Myofibroblastic Tumor of Mediastinum is a very rare, mostly benign tumor of the mediastinum (chest region). They generally occur in younger populations
• Inflammatory myofibroblastic tumor (IMT) is generally considered as a benign tumor with aggressive behavior (low-grade tumor), which can occur anywhere in the body
• The cause of Mediastinal Inflammatory Myofibroblastic Tumor is generally unknown, though an association with genetic mutations is observed. There are also no well-established risk factors for this tumor type
• The signs and symptoms of Inflammatory Myofibroblastic Tumor of Mediastinum may include chest pain and other obstructive symptoms such as cough. Complications, such as tumor recurrence after treatment, is known to occur
• The mainstay of treatment of Inflammatory Myofibroblastic Tumor of Mediastinum is a surgical excision that can be curative. The prognosis is generally good on tumor removal, but some tumors are known to recur and/or metastasize (rare cases)

Who gets Inflammatory Myofibroblastic Tumor of Mediastinum? (Age and Sex Distribution)

• Inflammatory Myofibroblastic Tumor of Mediastinum is typically seen in young adults and children, including in newborns and infants
• Very few cases of IMT of Mediastinum have been recorded in the medical literature
• Both males and females are affected and no gender preference is seen
• All races and ethnic groups are at risk for the condition

Note: Most inflammatory myofibroblastic tumors are found in the lung, which is the most common site of the tumor. In such cases, these tumors are frequently diagnosed in middle-aged adults. However, in contrast, the average age of presentation for extrapulmonary IMT (IMT outside the lung) is around 10 years.

What are the Risk Factors for Inflammatory Myofibroblastic Tumor of Mediastinum? (Predisposing Factors)

• Presently, the specific risk factors for Mediastinal Inflammatory Myofibroblastic Tumor are unknown or unidentified

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Inflammatory Myofibroblastic Tumor of Mediastinum? (Etiology)

The cause of development of Inflammatory Myofibroblastic Tumor of Mediastinum is generally unknown.

• Some research scientists believe that the cause of the condition is mostly due to genetic mutations, which results in tumor formation. In over 40% of the tumors, ALK gene mutation has been observed
• Some believe that the inflammatory myofibroblastic tumor is the result of an inflammatory reactive process and not a true tumor
• It is also believed by some researchers that the tumor may arise due to viral infections caused by human herpes virus 8 (HHV8) or Epstein-Barr virus (EBV)

What are the Sign and Symptoms of Inflammatory Myofibroblastic Tumor of Mediastinum?

The signs and symptoms depend on the size of the tumor. Specific signs and symptoms of Inflammatory Myofibroblastic Tumor of Mediastinum are based upon the tumor site and may include:

• Small tumors usually do not cause any symptoms. But, occasionally they may become painful, if they compress surrounding structure
• Chest pain
• Abnormal breathing due to compression may be present
• Mild pleural effusion (fluid in the lungs)
• Fever
• Cough; blood in cough sometimes
• Anemia

The tumor size may be about 3-7 cm.

How is Inflammatory Myofibroblastic Tumor of Mediastinum Diagnosed?

A diagnosis of Inflammatory Myofibroblastic Tumor of Mediastinum may be undertaken using the following tests and exams:

• Complete evaluation of family (medical) history, along with a thorough physical examination
• Plain X-ray of the chest
• CT or CAT scan with contrast of the chest usually shows a well-defined mass. This radiological procedure creates detailed 3-dimensional images of structures inside the body
• MRI scans of the lungs: Magnetic resonance imaging (MRI) uses a magnetic field to create high-quality pictures of certain parts of the body, such as tissues, muscles, nerves, and bones. These high-quality pictures may reveal the presence of the tumor

Although the above modalities can be used to make an initial diagnosis, a tissue biopsy of the tumor is necessary to make a definitive diagnosis to begin treatment. The tissue for diagnosis can be procured in multiple different ways which include: 

• Fine needle aspiration (FNA) biopsy of the tumor: A FNA biopsy may not be helpful, because one may not be able to visualize the different morphological areas of the tumor. Hence, a FNA biopsy as a diagnostic tool has certain limitations, and an open surgical biopsy is preferred
• Mediastinum core biopsy of the tumor
• Mediastinum open biopsy of the tumor using either thoracotomy or mediastinoscopy surgery

Tissue biopsy of the tumor:

• A tissue biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
• Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
• Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, and very rarely, electron microscopic studies to assist in the diagnosis

Note: Inflammatory Myofibroblastic Tumors are very rare. Due to this, it typically causes diagnostic challenges to the pathologist while trying to establish an accurate diagnosis.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Inflammatory Myofibroblastic Tumor of Mediastinum?

Some potential complications of Inflammatory Myofibroblastic Tumor of Mediastinum include:

• They can mimic cancer and cause considerable emotional stress in the affected individual
• Recurrence of the tumor after treatment, especially due to partial removal of IMT
• Large tumors can cause compression and thus dysfunction of the adjoining organs

IMTs are considered to be low-grade tumors and in a majority of individuals, they do not show any malignancy (95% or more cases). However, in about 5% of the individuals, the tumor can undergo a malignant transformation (called Malignant Inflammatory Myofibroblastic Tumor). In such cases, metastasis has been observed that may even result in fatal outcomes.

How is Inflammatory Myofibroblastic Tumor of Mediastinum Treated?

Inflammatory Myofibroblastic Tumor of Mediastinum may be treated through the following measures:

• Surgical removal of the entire tumor is the preferred method of treatment. The tumor may recur if they are removed partially
• In case of incomplete removal, radiation therapy may be a treatment option following surgery
• In young children, if the tumors cannot be surgically removed, then corticosteroid administration is found to be beneficial
• Chemotherapy may help, if the condition recurs , if there is a local invasion, or a distant metastasis is noted (in very rare cases)
• Occasionally, some tumors are known to disappear over time, without any treatment

Observation and periodic checkups to monitor the condition is recommended following treatment.

How can Inflammatory Myofibroblastic Tumor of Mediastinum be Prevented?

Presently, there are no specific methods or guidelines to prevent Inflammatory Myofibroblastic Tumor of Mediastinum.

What is the Prognosis of Inflammatory Myofibroblastic Tumor of Mediastinum? (Outcomes/Resolutions)

• An early diagnosis and prompt treatment of Inflammatory Myofibroblastic Tumor of Mediastinum generally yields better outcomes than a late diagnosis and delayed treatment
• The prognosis on timely surgical removal of the tumor is generally good. On a complete excision and removal, Mediastinal IMT is generally not known to recur
• Some tumors are known to spontaneously regress and disappear. But, some tumors are known to grow aggressively, recur, or even metastasize (occasionally)

Additional and Relevant Useful Information for Inflammatory Myofibroblastic Tumor of Mediastinum:

The following article link will help you understand other cancers and benign tumors:

http://www.dovemed.com/diseases-conditions/cancer/