Inflammatory Myofibroblastoma

Essential Information

Summarize

1. General remarks

 

Overview: Inflammatory myofibroblastic tumor (IMT) is a rare junctional or mesenchymal tumor that may occur anywhere in the body.

Prevalence: more common in children and adolescents.

Manifestations: mainly affect soft tissue and visceral organs, pulmonary inflammatory myofibroblastoma is more common, but can occur throughout the body.

Treatment: Surgical resection is the preferred treatment. Chemotherapy and hormone therapy are also used. Recent studies have shown that tumors with specific genetic mutations are suitable for targeted therapy.

Prognosis: Inflammatory myofibroblastoma is prone to recurrence, but rarely become cancerous and metastasize.

 

2. Disease definition

 

Inflammatory myofibroblastoma is a true mesenchymal tumor, where myofibroblasts are the primary cellular component, accompanied by an inflammatory response, characterized by the infiltration of numerous plasma cells and/or lymphocytes. Most cases of inflammatory myofibroblastoma do not progress to malignancy and are classified as benign tumors. However, a small number of cases may undergo distant metastasis, leading to cancerous changes with characteristics more akin to cancer. Considering the heterogeneity of these conditions, inflammatory myofibroblastoma is currently considered a low-grade malignant tumor, meaning it has a lower likelihood of becoming cancerous.

Historically, there has been a controversy about whether inflammatory myofibroblastoma is an inflammatory response or a tumor. It was once classified as an inflammatory pseudotumor, but in 1994 the World Health Organization (WHO) listed it as an independent disease and officially named it inflammatory myofibroblastoma.

 

 

 

Epidemiological

 epidemiology

 

Inflammatory myofibromatosis is a rare disease, with approximately 4 to 70 cases per 10,000 people worldwide. It is most commonly seen in children and adolescents, but has been reported in adults at all stages of life.

 

Etiology & Risk Factors

1. General remarks

 

The etiology and pathogenesis of inflammatory myofibromatosis are not clear. Some scholars believe that this kind of tumor directly originates from the malignant proliferation of human cells, but some scholars believe that it originates from the immune response of human body to infection or non-infection factors.

 

2. Basic etiology

 

Approximately 50% of patients have cancer cells with mutations in the anaplasticlymphoma kinase (ALK) gene, which is considered one of the contributing factors to the disease. ALK is a kinase protein that plays a crucial role in the development of certain neurons in the brain and nervous system. However, it can also act as a proto-oncogene, leading to cancer. It has been confirmed that in some inflammatory myofibroblastic tumors, the ALK gene undergoes rearrangement and fuses with other genes, resulting in abnormal overexpression or activation of the ALK protein.

 

3. Triggering factors

 

Many infections or non-infections have been suggested as possible associations with the development of inflammatory myofibromatosis.

These factors include pneumonia, various bacterial or viral infections (such as hepatitis B virus and EB virus), intrahepatic venous thrombophlebitis, previous trauma or surgery, past radiotherapy, steroid hormone use, and the body's immune mechanisms. There is also a hypothesis that inflammatory myofibroblastic tumors may arise from the body's immune response to another low-grade tumor. It is important to note that due to the rarity of inflammatory myofibroblastic tumors, there is insufficient evidence to confirm or refute these potential triggers.

Classification & Staging

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Clinical Manifestations

1. General remarks

 

Inflammatory myofibromatosis can occur throughout the body, most commonly in the lungs, abdomen, pelvis, and retroperitoneum, but also in soft tissues such as the larynx, head and neck, uterus, bladder, and kidney. Symptoms depend on the location and size of the tumor.

 

2. Typical symptoms

 

Inflammatory myofibromatosis occurs in about one-third of cases in the lungs and two-thirds in other sites. Symptoms are difficult to distinguish from other diseases, and sometimes there are symptoms of mass compression:

-Lung: cough, chest pain, even coughing up blood, difficulty breathing

-Abdomen, gastrointestinal tract, pelvis: abdominal pain, gastrointestinal discomfort, intestinal obstruction

-Head and neck: symptoms of compression by soft tissue masses, such as local pain, progressive swelling of the jaw and face, limited mouth opening, and difficulty swallowing

In a small number of patients, systemic symptoms such as fever, weight loss, night sweats or swollen lymph nodes were found during hospital visits.

There are also patients who have no clinical symptoms and are found during a physical examination. This type is called occult, and its patients have a longer survival period

 

3. Clinical classification

 

Due to the rarity of inflammatory myofibroblastic tumors, there is currently a lack of effective classification methods. However, tumor mutations provide some basis for molecular classification. For example, about half of these tumors have an ALK mutation. A study found that among patients without ALK mutations, some had tumors carrying ROS1 or PDGFRB fusion genes. These molecular features may guide future targeted therapies, although this research is still in its early stages.

Clinical Department

1. General remarks

 

Inflammatory myofibroblastoma is very rare, and the symptoms vary greatly depending on the location of the tumor, making diagnosis difficult. In clinical practice, many patients are diagnosed with inflammatory myofibroblastoma after excluding other diseases, and the final diagnosis depends on tissue biopsy.

 

2. Department of treatment

 

Because inflammatory myofibromatosis is rare and the location of the tumor is diverse, there is no clear department for patients to visit. Depending on the location of the tumor and symptoms, patients may visit different departments.

Examination & Diagnosis

 coherence check

 

● Imaging examinations: If a doctor suspects that a patient may have an inflammatory myofibroblastoma, they might use imaging techniques such as ultrasound, CT scans, and MRI to assess the tumor's location and size within the body. Typically, these imaging studies show that the size of an inflammatory myofibroblastoma can range from 1 cm to 20 cm, with most tumors appearing as soft tissue masses with uneven density. Among imaging methods, MRI is particularly effective in revealing the internal structure of the tumor and its relationship with the surrounding tissues.

● Organ biopsy: In order to confirm whether the tumor is an inflammatory myofibroma, doctors need to do a tissue biopsy, which involves taking a small amount of tumor tissue through a needle. The pathologist will identify the cell type in the biopsy tissue under a microscope to determine what kind of tumor it is.

● Blood tests: Some inflammatory myofibromatosis can also be associated with varying degrees of anemia, accelerated erythrocyte sedimentation rate, thrombocytosis or hypergammaglobulinemia, but these do not provide definitive diagnostic evidence. The biopsy described above is required for pathological diagnosis.

● Molecular Diagnosis: Molecular diagnosis is used to identify the molecular characteristics of diseases, including DNA, RNA, and proteins. Since inflammatory myofibroblastic tumors can be easily confused with other tumors or inflammatory infections, molecular diagnosis is sometimes necessary for a definitive diagnosis. Additionally, the results of molecular diagnosis can guide the decision on whether to use specific targeted therapies for the tumor

 

 antidiastole

 

Inflammatory myofibroblastoma, despite its wide range of clinical manifestations, shares common pathological features. Diagnosis primarily relies on percutaneous biopsy guided by ultrasound (using ultrasound as a guide to select the skin site with the shortest distance to the lesion, using a thick needle to puncture the skin and accurately obtain the diseased tissue) or biopsy taken during surgery.

In a biopsy, inflammatory myofibroblastoma is characterized by a chronic inflammatory reactive hyperplasia, which appears as granulomas composed of varying numbers of fibroblasts, leukocytes, and histiocytes. These granulomas may also exhibit necrosis and atypical cell proliferation. A few recurrent tumors exhibit features of malignant infiltration growth, necessitating differentiation from conditions such as spindle cell sarcoma, histiocytoma, and cancer.

Clinical Management

1. General remarks

 

The treatment of inflammatory myofibromatosis depends on the location of the tumor, the molecular characteristics of the tumor, and whether it has spread to other parts of the body, including surgery, chemotherapy, hormone therapy, and targeted therapy, with surgery as the preferred option.

 

2. Surgical treatment

 

Regardless of the location, the preferred treatment for inflammatory myofibroblastoma is surgical removal. According to current case studies, if the surgical removal is thorough, the risk of recurrence can be reduced, especially in tumors without significant infiltration, some cases may even achieve a complete cure. However, this condition tends to recur, and even with satisfactory resection, patients should still undergo regular follow-up examinations.

It is also important to note that even for tumors suitable for surgical removal, there are still challenges in practice. To ensure complete removal of the tumor, the extent of the surgery often needs to be much larger than the tumor itself. If the tumor is located in a vital organ, this may not be feasible. Furthermore, even if it is possible, the extensive tissue removal can place a significant strain on the patient's body.

 

3. Chemotherapy

 

Some patients with inflammatory myofibromatosis may develop into malignant tumors, and some patients may experience tumor progression or metastasis after surgery. If metastasis occurs, the prognosis is poor and can even be life-threatening. For these patients, chemotherapy is the next treatment option. Additionally, for those with recurrent or hard-to-remove tumors, chemotherapy is also a necessary option.

Due to its rarity, the chemotherapy regimen for inflammatory myofibroblastoma is still under exploration. Multiple regimens have been reported in various cases. Foreign reports include the combination of low-dose methotrexate and vinorelbine; and the alternating use of cisplatin, doxorubicin, ifosfamide, and etoposide. In China, chemotherapy has been reported using vincristine, cyclophosphamide, and actinomycin D.

 

4. Radiotherapy

 

In some case reports, radiotherapy has been used as a postoperative treatment after surgery for inflammatory myofibroblastic tumors. Given the rarity of such cases, it is not yet clear whether this approach is universally effective. Additionally, for patients who face difficulties with direct surgery, radiotherapy has been attempted to reduce tumor size first. The effectiveness of this method varies significantly among different patients, and caution is advised in practice.

 

5. Other treatments

 

A controversial treatment approach involves the use of either hormone-based or non-hormonal anti-inflammatory drugs. Given that inflammatory myofibromatosis is characterized by significant immune cell infiltration, in cases where the tumor is large and surgery is challenging, these drugs are sometimes used to reduce the tumor size before surgical intervention. The effectiveness of these medications varies widely, with reports indicating that they may be effective for some patients, and there have been cases where tumors were completely eliminated by hormones alone.

However, since these applications are generally in non-infiltrative inflammatory myofibromas, and most of these patients will be operated directly, hormone therapy is relatively rare in clinical practice.

 

6. Frontier treatment

 

Nearly half of the patients with inflammatory myofibroblastomas have tumors that exhibit ALK mutations. For these patients, if the tumor progresses or metastasizes after surgery, ALK inhibitors can be an option. Currently, ALK inhibitors available both domestically and internationally include crizotinib (Crizotinib), ceritinib (Ceritinib), aletinib (Aletinib), and brigatinib (Brigatinib).

Currently, data from phase I clinical trials of crizotinib and sericatinib indicate their effectiveness in treating inflammatory myofibroblastic tumors in patients with certain ALK mutations. Additionally, crizotinib is also an ROS1 inhibitor, and clinical cases have reported that inflammatory myofibroblastic tumors with ROS1 fusion genes but without ALK mutations also respond to crizotinib.

Prognosis

1. General remarks

 

Sarcomatoma of skeletal muscle fibers is a non-invasive tumor, and the treatment and prognosis of these patients are good. However, as it is a low-grade clinical tumor, some patients unfortunately encounter cancer, and the treatment of these patients still has many challenges, and the prognosis is poor, even life-threatening.

Most inflammatory myofibromatosis progresses slowly, with a local recurrence rate of less than 2% for lung tumors, a recurrence rate of 25% for extrapulmonary tumors, and a distant metastasis rate of less than 5%. Most recurrences occur within 2-3 years after surgery, and some patients have rapid disease progression.

Due to the small number of cases, there is currently insufficient statistical data on survival rates for inflammatory myofibromatosis. Overall, most patients survive more than 10 years if the tumor is completely removed by surgery.

 

2. Factors affecting recurrence

 

Because inflammatory myofibromatosis is so rare, the factors that influence recurrence have not been definitively concluded. Patients who have had incomplete surgical resection may be more likely to relapse, but these need to be confirmed with more research.

Follow-up & Review

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Daily Care

1. General remarks

 

Due to the variety of locations and rarity of inflammatory myofibromatosis, there is currently a lack of systematic information on daily care. However, due to the high recurrence rate of the disease, follow-up examination is required after treatment.

 

2. Follow-up

 

According to current research, follow-up for inflammatory myofibromatosis is primarily conducted through ultrasound and CT imaging, with intervals ranging from 3 months to 1 year. Furthermore, while most recurrences occur within 2-3 years after surgery, there have been reports of cases with recurrence occurring up to 10 years post-surgery. Therefore, patients should be prepared for long-term follow-up examinations.

 

3. Daily disease monitoring

 

Long-term follow-up and imaging examinations should be carried out to prevent missed visits and missed diagnosis.

 

4. Prevention

 

Because the cause of the disease is unknown, there is no better way to prevent the occurrence of inflammatory myofibroblastoma. Parents need to pay attention to their children's physical condition, and if they find related symptoms, they should seek medical treatment in time, as early detection and treatment can achieve the best results.

Cutting-edge therapeutic and clinical Trials

 not have

References

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Audit specialists

Wang Huanmin, director of the Department of Oncology, Beijing Children's Hospital affiliated to Capital Medical University

 

 Self-introduction

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