From the Guidelines
For patients with myofibroblastic tumor, also known as inflammatory myofibroblastic tumor (IMT), crizotinib is a recommended treatment option, particularly for tumors that test positive for ALK gene rearrangements, as supported by recent guidelines 1. Myofibroblastic tumor is a rare neoplasm composed of myofibroblastic spindle cells accompanied by an inflammatory infiltrate. These tumors can occur anywhere in the body but most commonly affect the lungs, abdomen, and pelvis.
Key Considerations
- Treatment typically involves complete surgical resection when possible, as this provides the best chance for cure and prevents local recurrence.
- For unresectable or metastatic tumors, targeted therapies may be considered, particularly ALK inhibitors like crizotinib for tumors that test positive for ALK gene rearrangements.
- Approximately 50% of IMTs harbor ALK gene rearrangements, making ALK testing an important part of the diagnostic workup, as noted in recent studies 1.
Follow-up and Prognosis
- Patients should undergo regular follow-up imaging after treatment, typically every 3-6 months initially, as these tumors have a recurrence rate of about 25%.
- While generally considered benign or of intermediate biological potential, a small percentage can behave aggressively with local invasion or distant metastasis.
- The pathogenesis involves myofibroblastic proliferation triggered by various factors including trauma, surgery, or infection, though many cases have no identifiable trigger, as discussed in the literature 1.
Treatment Options
- Crizotinib is a recommended treatment option for IMT patients with ALK gene rearrangements, with a dosage of 250 mg twice daily.
- Other treatment options, such as chemotherapy and radiation therapy, may be considered for patients who are not candidates for crizotinib or who have progressed on this treatment.
- Clinical trials may also be an option for patients with advanced or metastatic disease, as noted in recent guidelines 1.
From the Research
Myofibroblastic Tumor Characteristics
- Myofibroblastic tumors are a distinct entity of mesenchymal tumors, with inflammatory myofibroblastic tumors (IMTs) being a rare and ambiguous type of unknown etiology that can occur anywhere in the body 2.
- IMTs are characterized by diffuse infiltration of mixed inflammatory cells over proliferating myofibroblasts, with smooth muscle antigen immunoreactivity noted in fibroblastic spindle cells 2.
- Anaplastic lymphoma kinase (ALK) expression is found in approximately half of all IMTs, while the other half may have potentially targetable fusion genes or mutations such as ROS1, NTRK, and RET 3.
Diagnostic Challenges
- Clinical and radiological features of myofibroblastic tumors may not be specific, making diagnosis challenging 2, 4.
- Extensive thorough workup with histopathology, along with immunohistochemistry, is conducive to better clinical outcomes 2.
- Differential diagnosis with other spindle cell lesions, either benign or malignant, is important in practice, especially in the breast 5.
Treatment Strategies
- Surgical resection remains the cornerstone treatment for myofibroblastic tumors, offering favorable outcomes with rare recurrence 4, 6.
- Complete resection and achieving negative margins leads to excellent outcomes, with adjuvant radiation therapy used in some cases 6.
- Targeted therapy may be a promising approach, especially for tumors with ALK fusion genes or other potentially targetable mutations, although more clinical evidence is needed 3.
- Steroid administration and immunomodulation may also be used to manage symptoms and tumor progression, especially in cases where surgical resection is not possible 2.