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

• Inflammatory Pseudotumor of Kidney
• Plasma Cell Granuloma of Kidney
• Renal Inflammatory Fibrosarcoma

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

• Inflammatory Myofibroblastic Tumor of Kidney is a very rare, benign tumor affecting the kidney. These tumors generally occur in younger populations and may sometimes grow to large sizes
• 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 Renal Inflammatory Myofibroblastic Tumor is generally unknown, but it may be due to genetic mutations. There are no well-established risk factors for this tumor type
• The tumor may be in the parenchymal tissue of the kidney or in the renal pelvis. The signs and symptoms are generally non-specific, but may include abdominal pain, hematuria, fever, and weight loss. Complications, such as organ dysfunction due to large tumor sizes may occur
• The mainstay of treatment of Inflammatory Myofibroblastic Tumor of Kidney is a surgical excision (nephrectomy) that can be curative. The prognosis is generally good on tumor removal, but some tumors are known to recur and rarely they can even metastasize

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

• Inflammatory Myofibroblastic Tumor of Kidney is typically seen in young adults, though cases have been reported among older adults too
• Very few cases (less than 50) have been recorded in the medical literature, and so, Renal Inflammatory Myofibroblastic Tumor is an extremely rare tumor
• Both males and females are affected and no gender preference is seen. Typically, extrapulmonary tumors are known to have a slight female preference
• 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 Kidney? (Predisposing Factors)

• Presently, the specific risk factors for Renal 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 one’s 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 Kidney? (Etiology)

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

• Some research scientists believe that the cause is mostly due to genetic mutations, which results in inflammatory myofibroblastic 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 that it is 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 Signs and Symptoms of Inflammatory Myofibroblastic Tumor of Kidney?

The signs and symptoms depend on the size of the tumor. In many individuals, the tumor is known to be asymptomatic. The signs and symptoms of Inflammatory Myofibroblastic Tumor of Kidney may include:

• Small tumors usually do not cause any symptoms. But, occasionally they may become painful, if they compress surrounding structure
• Presence of an abdominal mass
• Swollen kidney may result in loss of kidney function
• Abdominal discomfort/pain or flank pain, which is the most common symptom noted
• Blood in urine (hematuria) without pain
• Fever
• Weight loss
• Anemia
• Some tumors may mimic renal cell carcinoma (RCC)

The tumor may be present in the renal pelvis, parenchymal tissue of kidney, or perirenal tissues. Large tumors may compress other abdominal organs, such as the pancreas and adrenal gland. Inflammatory Myofibroblastic Tumor of Kidney is typically well-defined and non-homogenous in appearance.

How is Inflammatory Myofibroblastic Tumor of Kidney Diagnosed?

A diagnosis of Inflammatory Myofibroblastic Tumor of Kidney is typically made during surgery. The following tests and exams may be undertaken:

• Complete evaluation of family (medical) history, along with a thorough physical examination
• Plain X-ray of the abdomen
• Ultrasound scan of the abdomen
• CT or CAT scan with contrast of the abdomen usually shows a well-defined mass. This radiological procedure creates detailed 3-dimensional images of structures inside the body
• MRI scans of the abdomen: 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

Invasive diagnostic procedures such as:

• Laparoscopy: A special device is inserted through a small hole into the abdomen, to visually examine it. If necessary, a tissue sample is obtained for further analysis. Exploration of the abdomen using a laparoscope is called ‘exploratory laparoscopy’
• Laparotomy: The abdomen is opened through an incision for examination, and if required, a biopsy sample obtained. Exploration of the abdomen using laparotomy procedure is called ‘exploratory laparotomy’

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
• Core biopsy of the tumor 
• Open biopsy of the tumor

Tissue biopsy of the tumor:

• A tissue biopsy of the nodule 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

A differential diagnosis may be considered to eliminate certain tumors, prior to arriving at a definitive diagnosis. The differential diagnosis includes:

• Angiomyolipoma
• Leiomyosarcoma
• Neurogenic tumors
• Renal cell carcinoma (RCC) and RCC with sarcomatoid features
• Rhabdomyosarcoma
• Xanthogranulomatous pyelonephritis polyps

Note: Inflammatory myofibroblastic tumors are generally rare. Due to this, it frequently 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 Kidney?

Some potential complications of Inflammatory Myofibroblastic Tumor of Kidney include:

• They can mimic kidney cancer and cause considerable emotional stress in the affected individual
• Narrowing of the ureter can lead to urination difficulties
• Rarely, recurrence of the tumor after treatment, especially due to partial removal of IMT
• Organ dysfunction due to large tumor sizes
• There is a less than 5% chance of metastasis of the tumor to other locations

How is Inflammatory Myofibroblastic Tumor of Kidney Treated?

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

• Surgical removal of the entire tumor is the preferred treatment method; generally, a partial nephrectomy is the treatment of choice
• In young children, if the tumors cannot be surgically removed, then corticosteroid administration is found to be beneficial
• Occasionally, some tumors are known to disappear over time, without any treatment
• Chemotherapy may help, if the condition recurs , if there is a local invasion, or a distant metastasis is noted (in very rare cases)

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

How can Inflammatory Myofibroblastic Tumor of Kidney be Prevented?

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

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

• An early diagnosis and prompt treatment of Inflammatory Myofibroblastic Tumor of Kidney generally yields better outcomes than a late diagnosis and delayed treatment
• The prognosis on timely surgical removal of the tumor is generally good. Some tumors are known to spontaneously regress and disappear
• Some tumors are known to recur following treatment. In rare cases, metastatic tumors are also observed; in which case, the prognosis may be unpredictable

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

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

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