Steroid responsive inflammatory myofibroblastic tumor of the lung evaluated by FDG PET/CT imaging

Inflammatory myofibroblastic tumor of the lung: a comprehensive narrative review of clinical and therapeutic insights

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal neoplasm classified by the World Health Organization as an intermediate malignancy with less than a 5% chance of metastasis. IMTs consist of myofibroblastic and spindle fibroblastic cells accompanied by inflammatory infiltration, primarily affecting patients under 16 years old, though they can also occur in adults. The etiology and pathogenesis of IMTs remain unclear, with possible contributing factors including inflammation, trauma, autoimmune diseases, prior surgery, viral infections, and uncontrolled myofibroblast proliferation. The primary treatment is complete surgical resection, which is associated with long-term survival and a significantly reduced recurrence rate of 2%, compared to 60% for incomplete resections. Chemotherapy is generally not recommended but may be necessary for unresectable tumors. Advances in histopathological diagnosis provide deeper insights into IMT biology, aiding in the selection of appropriate treatments. This paper presents a comprehensive review of the literature on this rare clinical entity.

Inflammatory myofibroblastic tumor from molecular diagnostics to current treatment

Inflammatory myofibroblastic tumor (IMT) is a rare neoplasm with intermediate malignancy characterized by a propensity for recurrence but a low metastatic rate. Diagnostic challenges arise from the diverse pathological presentation, variable symptomatology, and lack of different imaging features. However, IMT is identified by the fusion of the anaplastic lymphoma kinase (ALK) gene, which is present in approximately 70% of cases, with various fusion partners, including ran-binding protein 2 (RANBP2), which allows confirmation of the diagnosis. While surgery is the preferred approach for localized tumors, the optimal long-term treatment for advanced or metastatic disease is difficult to define. Targeted therapies are crucial for achieving sustained response to treatment within the context of genetic alteration in IMT. Crizotinib, an ALK tyrosine kinase inhibitor (TKI), was officially approved by the US Food and Drug Administration (FDA) in 2020 to treat IMT with ALK rearrangement. However, most patients face resistance and disease progression, requiring consideration of sequential treatments. Combining radiotherapy with targeted therapy appears to be beneficial in this indication. Early promising results have also been achieved with immunotherapy, indicating potential for combined therapy approaches. However, defined recommendations are still lacking. This review analyzes the available research on IMT, including genetic disorders and their impact on the course of the disease, data on the latest targeted therapy regimens and the possibility of developing immunotherapy in this indication, as well as summarizing general knowledge about prognostic and predictive factors, also in terms of resistance to systemic therapy.

Common and Uncommon Mimics of Thoracic Malignancy on PET/CT: Part 2—Pearls and Pitfalls of Lung Parenchyma and Mediastinum

In the thorax, there are multiple benign entities that may demonstrate hypermetabolism of fluorodeoxyglucose (FDG) leading to false-positive interpretation. Part 2 of this article aims to provide an overview of some benign thoracic entities that may mimic malignancy on positron emission tomography (PET)/CT in the lung parenchyma and mediastinum. Clinical history, anatomical correlation, and imaging features can help in narrowing the differential diagnosis. This review is divided into two parts: part 1 covers the pleura and chest wall; part 2 will cover lung parenchyma and mediastinum.

Inflammatory myofibroblastic tumor directly invading the right first rib treated with oral steroids: a case report

BACKGROUND

We present a case of an inflammatory myofibroblastic tumor cured with a short period of steroid administration, a treatment previously unreported for such cases.

CASE PRESENTATION

A 49-year-old man had a chief complaint of chest pain for more than 3 days. Computed tomography (CT) revealed a tumoral lesion suspected to have infiltrated into the right first rib and intercostal muscles, with changes in lung parenchymal density around the lesion. The maximal standardized uptake value on 18 F-fluorodeoxyglucose positron emission tomography/computed tomography was high (16.73), consistent with tumor presence. CT-guided biopsy revealed an inflammatory myofibroblastic tumor with no distant metastases. Surgery was indicated based on the disease course. However, he had received an oral steroid before the preoperative contrast-enhanced CT scan due to a history of bronchial asthma, and subsequent CT showed that the tumor shrank in size after administration; he has been recurrence-free for more than a year.

CONCLUSIONS

Surgery is still the first choice for inflammatory myofibroblastic tumors, as the disease can metastasize and relapse; however, this condition can also be cured with a short period of steroid therapy.

PET/CT Imaging of Inflammatory Myofibroblastic Tumor of the Thigh

A 13-year-old male patient presented with right leg pain and walking difficulty. Contrast-enhanced magnetic resonance imaging showed a softtissue lesion between muscle groups in the anterior half of the right thigh. The excisional biopsy result ended in an inflammatory myofibroblastic tumor (IMT). The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan showed hypermetabolism in the multifocal soft tissue lesion and also confirmed that no other distant foci were present. A three-phase Tc-99m-methylene diphosphonate study of the region showed heterogeneously increased vascularity within the region. We described an unusual case of IMT in a pediatric patient and the importance of PET/CT scanning to delineate the lesion.