Inflammatory myofibroblastic tumor: The experience of the European pediatric Soft Tissue Sarcoma Study Group (EpSSG)

Recurrent Inflammatory Myofibroblastic Tumor of Larynx Harboring a Novel THBS1::ALK Fusion

Inflammatory myofibroblastic tumor (IMT) is a rare soft tissue tumor primarily occurring in the abdominopelvic region of young patients, and it is characterized by spindle-shaped myofibroblasts, or fibroblasts surrounded by inflammatory infiltrate. Herein, we report a case of a 24-year-old male with a firm submucosal mass in the anterior right vocal fold diagnosed as an IMT that recurred 14 months later. The tumor demonstrated a novel THBS1::ALK fusion containing Exons 1-7 of the thrombospondin 1 (THBS1) gene fused to Exon 19 of the anaplastic lymphoma kinase (ALK) gene via next-generation sequencing with the NextSeq sequencer. The fusion of THBS1 to ALK potentially results in increased expression and constitutive activation of the ALK kinase domain. These findings not only broaden the repertoire of known ALK fusion partners implicated in tumorigenesis but also provide a novel avenue for investigating the etiology of recurrent IMT by considering this fusion event as a causal factor. To our knowledge, this is the second case of IMT of the larynx with this novel mutation reported in the literature and the first such case with a detailed description of this specific fusion and clinical recurrence.

Treatment and outcomes in pediatric inflammatory myofibroblastic tumors - A systematic review of published studies

Inflammatory myofibroblastic tumor (IMT) is a soft tissue neoplasm which can be locally invasive, recur, or in rare cases metastasize. Often originating from the abdomen or thorax, IMT most commonly affects children and young adults. Due to its rarity comprehensive reports detailing clinical management and outcome(s) are sparse and often based on limited index case numbers. This study systematically analyzes outcome metrics of pediatric IMT and identifies risk factors for mortality. Medline/Embase databases were searched in accordance with PRISMA guidelines. Final analysis included 57 studies with 673 IMT patients (355 males, 53 %). Individual patient data was available for 405 cases with a median follow-up period of 36 months. Tumor sites included abdomen/pelvis (n = 233, 58 %), thorax (n = 125, 31 %), head/neck (n = 34, 8 %), and extremities (n = 13, 3 %). Surgical tumor resection was the mainstay of treatment, while only 20 patients (5 %) were treated non-operatively. Recurrence(s) were reported in 80 patients (20 %) with 34 (12 %) requiring reoperation. Positive tumor margins were a significant risk factor for tumor recurrence (p < 0.0001). Chemo/radiotherapy was reported in 98 patients (25 %). Most patients (94 %) survived; 81 % (n = 237) with no evidence of recurrent disease, 14 % (n = 41) were alive with disease, and 25 (6 %) died of disease. Positive margins at primary operation, and metastatic disease were associated with mortality (p < 0.0001 for both). IMT is a rare tumor with favorable outcome for the majority of patients. Whilst most patients will present with benign tumors, complete surgical resection (R0) is crucial, as positive surgical margins are a significant risk factor for tumor recurrence and mortality.

Pediatric skull inflammatory myofibroblastic tumor: a rare case report and literature review

Inflammatory myofibroblastic tumors (IMTs) represent rare neoplasms, particularly infrequent in the pediatric skull. We present a novel case of a newborn male with a 5 cm right temporal mass and discuss current diagnostic and treatment options for IMTs. A multidisciplinary effort to surgically remove the lesion was successful, and the patient's skull defect healed without neurological deficits. The etiology of IMTs remains elusive, with proposed associations with chromosomal mutations in the anaplastic lymphoma kinase (ALK) gene. Surgical excision remains the primary treatment for IMTs. Promising pharmacological treatments, like Crizotinib, warrant further research into understanding potential alternatives in IMT management.

Individualized targeted treatment in a case of a rare TFG::ROS1 fusion positive inflammatory myofibroblastic tumor (IMT)

BACKGROUND

Inflammatory myofibroblastic tumor (IMTs) are rare mesenchymal neoplasms with slow growth. Resection is considered as therapeutic standard, with chemotherapy being insufficiently effective in advanced disease. ALK translocations are present in 50% of cases, ROS1 fusions (YWHAE::ROS1, TFG::ROS1) are extremely rare. Here, we present a case with TFG::ROS1 fusion and highlight the significance of molecular tumor boards (MTBs) in clinical precision oncology for post-last-line therapy.

CASE PRESENTATION

A 32-year-old woman presented with IMT diagnosed at age 27 for biopsy and treatment evaluation. Previous treatments included multiple resections and systemic therapy with vinblastine, cyclophosphamide, and methotrexate. A computed tomography scan showed extensive tumor infiltration of the psoas muscles and the posterior abdomen. Next generation sequencing revealed an actionable ROS1 fusion (TFG::ROS1) with breakpoints at exon 4/35 including the kinase domain and activating the RAS-pathway. TFG, the Trk-fused gene, exerts functions such as intracellular trafficking and exhibits high sequence homology between species. Based on single reports about efficacy of ROS1-targeting in ROS1 translocation positive IMTs the patient was started on crizotinib, an ATP-competitive small molecule c-MET, ALK and ROS1-inhibitor. With a follow-up of more than 9 months, the patient continues to show a profound response with major tumor regression, improved quality of life and no evidence for severe adverse events.

CONCLUSION

This case underscores the importance of the availability of modern molecular diagnostics and interdisciplinarity in precision oncology to identify rare, disease-defining genotypes that make an otherwise difficult-to-treat disease targetable.

Inflammatory endobronchial polyps unleashing recurrent pneumothorax: A case report

Inflammatory endobronchial polyps (IEPs) are rare benign lesions that originate from the bronchial mucosa. While pneumothorax is a well-known complication of various pulmonary conditions, its association with IEPs is exceedingly uncommon and poorly understood. This case report presents a unique and explosive encounter of a patient with an inflammatory endobronchial polyp who experienced a pneumothorax, shedding light on the clinical presentation, diagnostic challenges, and management strategies for this rare entity.

Inflammatory myofibroblastic tumor of the upper arm: A case report

RATIONALE

Inflammatory myofibroblastic tumor (IMT) is an uncommon benign myofibroblastic tumor that usually occurs in the lung, mediastinum, abdomen and vulvovaginal region. IMT of the upper arm is exceedingly rare with unknown etiology. Pathology plays a major role in the diagnosis of IMT, and radiological characteristics of the condition are crucial for differential diagnosis.

PATIENT CONCERNS

A 62-year-old woman was admitted to our hospital for a complaint of a mass in her left upper limb with progressive numbness in the extremity. Ultrasound examination of the brachial artery (BA) revealed a hypoechoic mass with well-defined borders and a substantial blood flow, and the mass was also shown to be greatly enhanced on computed tomography (CT) and magnetic resonance imaging (MRI).

DIAGNOSIS

The subsequent histopathological and immunohistochemical studies led to the diagnosis of IMT.

INTERVENTION

The patient was referred for surgery. The soft tissue tumor resection, left median nerve release operation, brachial artery vascular grafting, and arterial anastomosis were performed.

OUTCOME

Favorable outcome was observed. The patient recovered well from the procedure and did not experience any further complications or tumor recurrence.

LESSONS

In this report, we describe a case of IMT of the upper arm with BA involvement. The case expands the differential diagnosis of limb neoplasm and broadens the understanding of its ultrasonic and radiological imaging features. It also serves as a further example of an uncommon region distinct from conventional IMT. Further studies on the etiology and therapeutic strategies are needed.

Update of Diagnosis and Targeted Therapy for ALK+ Inflammation Myofibroblastic Tumor

OPINION STATEMENT: Inflammatory myofibroblastic tumor (IMT), characterized by intermediate malignancy and a propensity for recurrence, has presented a formidable clinical challenge in diagnosis and treatment. Its pathological characteristics may resemble other neoplasms or reactive lesions, and the treatment was limited, taking chemotherapies as the only option for those inoperable. However, discovering anaplastic lymphoma kinase (ALK) protein expression in approximately 50% of IMT cases has shed light on a new diagnostic approach and application of targeted therapies. With the previous success of combating ALK+ non-small-cell lung cancers with ALK tyrosine kinase inhibitors (TKIs), crizotinib, a first-generation ALK-TKI, was officially approved by the U.S. Food and Drug Administration in 2020, to treat unresectable ALK+ IMT. After the approval of crizotinib, other ALK-TKIs, such as ceritinib, alectinib, brigatinib, and lorlatinib, have proven their efficacy on ALK+ IMT with sporadic case reports. The sequential treatments of targeted therapies in may provide the insight into the choice of ALK-TKIs in different lines of treatment for unresectable ALK+ IMT.

Diagnosis of inflammatory myofibroblastic tumor in a pediatric patient initially suspected of tuberculosis

BACKGROUND

Symptoms of inflammatory myofibroblastic tumor (IMT) are atypical, and histopathological misdiagnosis of IMT is still inevitable. Here we present a pediatric case that an eight-year-old boy with recurrent fever for fifteen months, received anti-tuberculosis therapy for five months and was ultimately confirmed to be IMT.

CASE PRESENTATION

An eight-year-old boy experienced a recurrent fever for fifteen months, accompanied by cough, vomiting, meteorism, night sweating, and emaciation. Thoracoabdominal computer tomography revealed multiple enlarged lymph nodes in the thorax, abdomen, and axilla, as well as minimal bilateral pleural effusion. Histopathological examinations of the intestines and greater omentum implied fibrous tissue hyperplasia along with eosinophil and lymphocyte infiltration. The patient was initially misdiagnosed with tuberculosis, and symptoms were relieved partially following anti-tuberculosis treatment. However, after four months, the symptoms aggravated again and a subsequent histopathological analysis of a second sample from the greater omentum revealed the presence of IMT. Eventually, after surgical resection of the lesions and chemotherapy, the clinical symptoms in the child gradually alleviated.

CONCLUSIONS

The clinical course of IMT is variable, and pediatricians should pay attention to differentiating IMT from tuberculosis.

Case report: Uniportal video-assisted thoracoscopic sleeve lobectomy in a 6-year-old patient with inflammatory myofibroblastic tumor (IMT)

Inflammatory myofibroblastic tumor (IMT) is a rare neoplasm that can occur in various organs, including the lung. Surgical resection is usually the preferred treatment for localized IMT.A 6-year-old female was admitted to our hospital with complaints of "coughing and vomiting for 6 days". A chest CT scan revealed occlusion of the left main bronchus, segmental atelectasis of the left lower lung, and cystic low-density shadows along the bronchial pathway. Subsequent fiberoptic bronchoscopy confirmed the diagnosis of IMT through pathological biopsy. After excluding surgical contraindications, the patient underwent uniportal video-assisted thoracoscopic sleeve lobectomy for treatment. The patient had an uneventful postoperative course and was discharged four days after surgery. After one month, the patient received a follow-up examination and reported no significant discomfort. A chest CT scan revealed no postoperative complications.Our experience suggests that uniportal video-assisted thoracoscopic surgery may be a safe and effective approach for the treatment of pediatric patients with IMT requiring complex surgical procedures such as sleeve lobectomy and tracheoplasty.

Inflammatory myofibroblastic tumors: recent progress and future of targeted therapy

An inflammatory myofibroblastic tumor is a rare component of bone and soft-tissue sarcomas that has distinct pathological features as a lymphoplasmacytic inflammatory infiltrate. As is the case for other non-small round cell sarcomas, surgical resection remains the standard treatment strategy for inflammatory myofibroblastic tumors, but recurrence is possible. Concerning systemic therapy, the available data for conventional chemotherapy (such as those of doxorubicin-based regimens) are limited, and case reports of anti-inflammatory inflammatory myofibroblastic tumor treatments describe some degree of symptom relief and efficacy against tumor progression. However, as more information about cancer genomics accumulates, the potential for molecularly targeted therapies for inflammatory myofibroblastic tumors has become more promising. Approximately half of inflammatory myofibroblastic tumors harbor anaplastic lymphoma kinase (ALK) fusion genes, and the other half could have potentially targetable fusion genes or mutations such as ROS1, NTRK and RET; case reports demonstrating the clinical efficacy of treatments targeted to inflammatory myofibroblastic tumor have been published, as have several prospective clinical trials. Few drugs are approved for the treatment of inflammatory myofibroblastic tumor, and most of them were approved for tumor-agnostic indications. Drugs that could be used for pediatric indications and dosing in inflammatory myofibroblastic tumor have also not been established. To provide effective targeted therapy for rare diseases such as inflammatory myofibroblastic tumor, it is necessary to obtain clinical evidence by designing and performing clinical trials and to find a path toward regulatory approval.

Tracheal Inflammatory Myofibroblastic Tumour ALK+ as Cause of Dyspnea in a 10 Years Old Child

Inflammatory myofibroblastic tumours are rare lesions that could occur in airways. We report a 10 years old male who complains about dyspnea after physical exercise. Making CT and RMI images and a biopsy, we make an accurate diagnosis of an inflammatory myofibroblastic tumour ALK+. After treatment with a subtotal resection and crizotinib as adjuvant, we achieve a complete remission.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03775-5.

Cardiac and Pericardial Neoplasms in Children: Radiologic-Pathologic Correlation

Primary cardiac and pericardial neoplasms are rare in the pediatric population and can include both benign and malignant lesions. Rhabdomyomas, teratomas, fibromas, and hemangiomas are the most common benign tumors. The most common primary cardiac malignancies are soft-tissue sarcomas, including undifferentiated sarcomas, rhabdomyosarcomas, and fibrosarcomas. However, metastatic lesions are more common than primary cardiac neoplasms. Children with primary cardiac and pericardial tumors may present with nonspecific cardiovascular symptoms, and their clinical presentation may mimic that of more common nonneoplastic cardiac disease. The diagnosis of cardiac tumors has recently been facilitated using noninvasive cardiac imaging. Echocardiography is generally the first-line modality for evaluation. Cardiac MRI and CT are used for tissue characterization and evaluation of tumor size, extension, and physiologic effect. The varied imaging appearances of primary cardiac neoplasms can be explained by their underlying abnormality. Treatment of these lesions varies from conservative management, with spontaneous regression of some lesions such as rhabdomyomas, to surgical resection, particularly in patients with associated heart failure. With adequate imaging techniques and knowledge of the pathologic basis of the neoplasm, it is often possible to differentiate benign from malignant tumors, which can greatly affect adequate and timely treatment. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Inflammatory Myofibroblastic Tumor With ROS1 Gene Fusions in Children and Young Adolescents

PURPOSE

Inflammatory myofibroblastic tumors (IMTs) are often driven by anaplastic lymphoma kinase fusions and less frequently by alternative fusions such as ROS1. We describe the clinical characteristics, treatment approach, and outcome for a series of young patients with IMTs and ROS1 alterations.

METHODS

This was a retrospective, international, multicenter study analyzing young patients (younger than 21 years) with ROS1-altered IMTs treated in 10 European referral centers between 2014 and 2022. Patients were included in the European pediatric Soft tissue sarcoma Study Group NRSTS-2005 protocol or registered in the Soft Tissue Sarcoma Registry. Primary surgery was recommended if a microscopic radical resection was feasible without mutilation. No standard systemic treatment protocol was available, but several medical options were recommended.

RESULTS

A total of 19 patients (median age 8.3 years) were included. Most patients had a biopsy at diagnosis (Intergroup Rhabdomyosarcoma Study [IRS] I; n = 2, IRS II; n = 1, IRS III biopsy; n = 11, IRS III resection; n = 3, IRS IV; n = 2). Twelve patients received neoadjuvant systemic therapy in first line (four received multiple treatments): high-dose steroids (n = 2), vinorelbine/vinblastine with methotrexate (n = 6), or ROS1 inhibitors (n = 8). After a median follow-up of 2.8 years (range, 0.2-13.4), seven patients developed an event. The 3-year event-free survival was 41% (95% CI, 11 to 71), and the 3-year overall survival was 100%.

CONCLUSION

Outcome for ROS1-altered IMTs appears excellent. A complete resection at diagnosis was often not feasible, and most patients needed neoadjuvant therapy. Patients who developed a tumor event could be cured with reinitiation of systemic therapy and/or surgery. This approach illustrates a switch in treatment philosophy moving from immediate, often mutilating, surgery to systemic (targeted) therapy as a bridge to more conservative surgery later in the treatment course.

Current management of benign retroperitoneal tumors

Benign retroperitoneal tumors (BRT) represent a rare group of heterogeneous diseases. The literature lacks high-quality evidence about the optimal management of BRT, and most of the information available takes the form of case reports or case series. The aim of this review is to provide an overview of current management strategies for adult patients with BRT. A literature search using PubMed indexed articles was conducted and BRT were classified into five different biological subgroups: 1) lipomatous tumors, 2) smooth muscle tumors, 3) peripheral nerve sheath tumors, 4) myofibroblastic tumors, and 5) others. Tumors that are primarily pelvic in origin were excluded. Despite the significant heterogeneity of the disease, several generic considerations have emerged and can be applied to the management of BRT. Specifically, the risk of misdiagnosing a BRT with another pathology such as retroperitoneal sarcoma is notable. When encountered, suspected BRT should therefore be referred to a specialized sarcoma center. Multidisciplinary tumor boards, present at these centers, have a pivotal role in managing BRT. The decision of whether to offer surgery, nonsurgical treatment or a "watch-and-wait" approach should be made after multidisciplinary discussion, depending on tumor histology. Moving forward, collaborative research efforts dedicated to BRT remain crucial in gathering evidence and knowledge to further optimize patient care.

Inflammatory myofibroblastic tumor of the thyroid gland

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal tumor with low incidence, which is extremely rare in the thyroid. At present, there is a lack of understanding regarding the etiology, pathogenesis, diagnosis and treatment of thyroid IMT. To improve the understanding of the disease, this article reviews the pathogenesis, clinical manifestations, pathology and immunohistochemistry, diagnosis, therapy and prognosis of thyroid IMT.

Fetal Lung Interstitial Tumor (FLIT): Review of The Literature

Fetal lung interstitial tumor (FLIT) is an extremely rare pediatric lung tumor that shares radiological features with congenital pulmonary malformations (cPAM) and other lung neoplasms. A review of the literature, together with the first European case, are herein reported. A systematic and manual search of the literature using the keyword "fetal lung interstitial tumor" was conducted on PUBMED, Scopus, and SCIE (Web of Science). Following the PRISMA guidelines, 12 articles were retrieved which describe a total of 21 cases of FLIT, and a new European case is presented. A prenatal diagnosis was reported in only 3 out of 22 (13%) cases. The mean age at surgery was 31 days of life (1-150); a lobectomy was performed in most of the cases. No complications or recurrence of disease were reported at a mean follow-up of 49 months. FLIT is rarely diagnosed during pregnancy, may present at birth with different levels of respiratory distress, and requires prompt surgical resection. Histology and immunohistochemistry allow for the differentiation of FLIT from cPAM and other lung tumors with poor prognosis, such as pleuropulmonary blastoma, congenital peri-bronchial myofibroblastic tumor, inflammatory myofibroblastic tumor, and congenital or infantile fibrosarcoma.

Spectrum of kinase gene rearrangements in a large series of paediatric inflammatory myofibroblastic tumours

INTRODUCTION

Inflammatory myofibroblastic tumours (IMTs), being an exceptionally rare category of paediatric neoplasms, often contain druggable gene rearrangements involving tyrosine kinases.

METHODS AND RESULTS

This study presents a large consecutive series of IMTs which were analysed for the presence of translocations by the PCR test for 5'/3'-end ALK, ROS1, RET, NTRK1, NTRK2 and NTRK3 unbalanced expression, variant-specific PCR for 47 common gene fusions and NGS TruSight RNA fusion panel. Kinase gene rearrangements were detected in 71 of 82 (87%) IMTs (ALK: n = 47; ROS1: n = 20; NTRK3: n = 3; PDGFRb: n = 1). The test for unbalanced expression had 100% reliability in identifying tumours with ALK fusions, but failed to reveal ROS1 rearrangements in eight of 20 (40%) ROS1-driven IMTs; however, ROS1 alterations were detectable by variant-specific PCR in 19 of 20 (95%) cases. ALK rearrangements were particularly common in patients below 1 year of age (10 of 11 (91%) versus 37 of 71 (52%), P = 0.039). ROS1 fusions occurred more often in lung IMTs than in tumours of other organs (14 of 35 (40%) versus six of 47 (13%), P = 0.007). Among 11 IMTs with no kinase gene rearrangement identified, one tumour demonstrated ALK activation via gene amplification and overexpression, and another neoplasm carried COL1A1::USP6 translocation.

CONCLUSIONS

PCR-based pipeline provides a highly efficient and non-expensive alternative for molecular testing of IMTs. IMTs with no detectable rearrangements need further studies.

Pediatric inflammatory myofibroblastic tumor of the bladder with ALK-FN1 fusion successfully treated by alectinib

An inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm characterized by the proliferation of myofibroblasts and inflammatory cell infiltration. Although radical resection is the only established treatment strategy for IMT, it can cause functional disorders when vital organs are affected. We describe a case of pediatric IMT of the bladder with FN1-ALK (fibronectin 1-anaplastic lymphoma kinase) fusion. Radical resection might lead to urinary disturbance due to the large tumor size at diagnosis. However, the tumor was successfully treated with alectinib, a second-generation ALK inhibitor, followed by transurethral resection of the bladder tumor without any complications.

Inflammatory myofibroblastic tumor of the mesentery with a SQSTM1::ALK fusion responding to alectinib

BACKGROUND

Inflammatory myofibroblastic tumor (IMT) is an ultra-rare soft tissue neoplasm associated with fusion proteins encompassing the anaplastic lymphoma kinase (ALK) protein fused to a variety of partner proteins. Data regarding response to ALK-targeting agents based on fusion partner is limited.

CASE

A 30-year-old female sought emergency care after onset of abdominal and lower back pain in 2019. Computed tomography (CT) demonstrated a cystic, mesenteric mass within the pelvis measuring up to 8.9 cm. Complete laparoscopic excision of the mass from the mesentery of the right colon and terminal ileum was performed. Pathologic assessment revealed IMT with a fusion between sequestosome 1 and ALK (SQSTM1::ALK), described in only two other cases of IMT. Four months after surgery, CT revealed multi-focal, unresectable disease recurrence. She was referred to the University of Washington/Fred Hutchinson Cancer Center and placed on therapy with alectinib, after which she experienced a partial response. Three years after IMT recurrence, disease remains under control.

CONCLUSION

This is the third reported case of IMT associated with the novel SQSTM1::ALK fusion protein, and the second treated with alectinib. Treatment with the ALK inhibitor alectinib appears to be active in this setting.

Multifocal spinal inflammatory myofibroblastic tumors in a juvenile paraparetic dog

A 1-year-old, female English Bulldog presented with a 10-day history of progressive paraparesis. Neuroanatomical localization was consistent with T3-L3 segment myelopathy. Magnetic resonance imaging (MRI) revealed a severely compressive, mildly contrast enhancing, extradural, dorsal, broad-based mass at the level of L3-4. Similar, non-compressive, smaller nodules were present along the extradural space and dura mater of the caudal lumbar spine. Owners elected euthanasia based on these imaging findings and progressive clinical signs. Necropsy, histopathology and immunohistochemistry revealed a mesenchymal mass and nodules, admixed with numerous inflammatory cells. The diagnosis of an extradural inflammatory myofibroblastic tumor (IMT) with a multifocal presentation was made.

The significance of margins in pediatric Non-Rhabdomyosarcoma soft tissue sarcomas: Consensus on surgical margin definition harmonization from the INternational Soft Tissue SaRcoma ConsorTium (INSTRuCT)

BACKGROUND

Margin status following surgery in children, adolescents, and young adults with soft tissue sarcomas is controversial and has been defined differently by various specialties, with definitions changing over time and by cooperative group. The International Soft Tissue Sarcoma Consortium (INSTRuCT) is a collaboration of the Children's Oncology Group (COG) Soft Tissue Sarcoma Committee, European pediatric Soft Tissue sarcoma Study Group (EpSSG), and the European Cooperative Weichteilsarkom Studiengruppe (CWS) devoted to improving patient outcomes by pooling and mining cooperative group clinical trial data.

METHODS

The INSTRuCT non-rhabdomyosarcoma soft tissue sarcoma (NRSTS) working group aimed to develop international harmonized recommendations regarding surgical margin assessment and definitions in children and adolescents with soft tissue tumors.

RESULTS AND CONCLUSION

This review addresses accepted principles and areas of controversy, including the perspectives of surgeons, pathologists, radiation oncologists, and pediatric oncologists, to develop a framework for building common guidelines for future research.

Uterine inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumor (IMT) is recognized as a true neoplasm of unknown etiology, but its pathogenesis is related to abnormalities in the ALK gene. This is an uncommon tumor with a wide anatomic distribution and often constitutes a challenging diagnosis owing to its histological similarities with other tumors. Uterine IMTs are rare and their detailed characteristics should be described based on case reports and small case series. Thus, we performed a comprehensive review of the literature showing that uterine IMTs show a wide range of age at diagnosis (median, 39 years), and a symptomatology similar to that of common leiomyomas, only rarely presenting with inflammatory manifestations. IMTs represent 0.1% of "leiomyomas," an estimate that increases to 10% for pregnant women and to 14% for the smooth muscle tumors of uncertain malignant potential (STUMP) category of tumors, implying that tumors excised during pregnancy, STUMPs, and leiomyosarcomas should be systematically screened with ALK immunohistochemistry, as this is a targetable abnormality. Most reported cases are ALK-positive; the fusion partners vary, but in pregnancy-associated tumors, TIMP3 prevails. Almost 25% of the patients will show an aggressive course, and this is associated with older age, non-pregnancy-associated tumors, larger tumors, infiltrative tumor border, absence of abundant inflammation, atypia, important mitotic activity, and necrosis.

Treatment modalities of ALK-positive relapsed/refractory inflammatory myofibroblastic tumor of the brain and lungs in 7-year-old girl: case-based reviews

PURPOSE

Inflammatory myofibroblastic tumor (IMT) belongs to mesenchymal neoplasm of intermediate malignancy in WHO classification. Primary CNS disease or CNS metastases (CNS-IMT) occur in minority. We describe a case of relapsed/refractory IMT of lungs with multiple brain metastases in young child who achieved long-term complete response after alectinib. This systematic review also summarizes treatment modalities and outcome of children and adolescent with CNS-IMT.

METHODS

PRISMA 2020 guideline was applied to select an article from PubMed, Scopus, and Cochrane databases without time limits. This review focused on children and adolescent 0-24 years of age with CNS-IMT or inflammatory pseudotumor (CNS-IPT). The clinical characteristics and treatment outcome were explored.

RESULTS

A total of 51 patients in 49 publications were identified. Median age of patients with CNS-IMT/IPT was 15-year-old and 60.8% were male. The most common location of tumor was cerebral cortex (54.9%). Complete resection of CNS-IMT/IPT was performed in 27 cases with 100% complete response and 18.5% recurrence. Nearly half of patients who received partial resection without adjuvant therapy experienced progressive disease, while the contrast group totally achieved partial response. Overall responses in 7 patients treating with ALK inhibitors were 57.1% durable complete response and 42.9% transient partial response.

CONCLUSION

First-line treatment of CNS-IMT/IPT is complete resection. Patients who received partial tumor removal might have benefit from adjuvant therapy. ALK inhibitors reveal a promising result in unresectable CNS-IMT/IPT. Our case has shown a success in treating relapsed and refractory CNS-IMT as well as the primary site using 2nd-generation ALK inhibitor.

Inflammatory Myofibroblastic Tumor of the Sigmoid Colon in an Infant: A Case Report and Literature Review

Inflammatory myofibroblastic tumor (IMT) infrequently involves the sigmoid colon, and has not previously been described in an infant sigmoid colon. An inflammatory myofibroblastic tumor arose from the sigmoid colon of an 11-month-old boy, confirmed by anaplastic lymphoma kinase (ALK), smooth muscle actin (SMA) and desmin immunohistochemical staining. The patient recovered well after complete resection of the tumor. Sigmoid IMT can occur in infancy. This eighth case is the youngest so far. The child did well after surgical resection.

Case Report: Clinical response to anaplastic lymphoma kinase inhibitor-based targeted therapy in uterine inflammatory myofibroblastic tumor harboring ALK-IGFBP5 fusion

Background

An inflammatory myofibroblastic tumor (IMT) is a mesenchymal tumor with a prevalence ranging from 0.04% to 0.7% worldwide, in which the lung is the most common predilection site, accounting for 33% of cases, followed by the abdomen, pelvis, mesentery, and uterus. Approximately 50% of uterine IMTs present as anaplastic lymphoma kinase (ALK) positive along with ALK gene fusion, which lays a solid foundation for the development of ALK-based target therapy to optimize treatment strategies.

Case presentation

Herein we describe a 57-year-old woman who presented with a slow-growing mass in the uterus for over 10 years and then received surgical resection because of significant progressive enlargement of the mass during follow-up. She was diagnosed with uterine leiomyosarcoma (LMS) with no further interventions until recurrence. We revised the diagnosis to uterine IMT based on diffuse ALK expression, ALK-IGFBP5 gene fusion, and the morphologic features of the tumors by pathology consultation. Based on these, we recommended an ALK tyrosine kinase inhibitor (TKI) treatment, crizotinib (250 mg bid), and she achieved a complete response (CR) with at least 18 months of progression-free survival (PFS). We monitored the dynamics of target lesions and peripheral blood cells at regular intervals through CT scans and routine blood tests during the treatment process. We present patient responses to ALK inhibitor-based targeted therapy with uterine IMT harboring ALK-IGFBP5 fusion, and the neutrophil-to-lymphocyte ratio (NLR) may be an effective indicator to predict prognosis.

Infantile Fibrosarcoma and Other Spindle Cell Neoplasms of Infancy. A Review of Morphologically Overlapping yet Molecularly Distinctive Entities

BACKGROUND

Regardless of age at presentation, many soft tissue neoplasms have overlapping histopathologic and immunophenotypic features to serve as a diagnostic challenge.

CASE REPORT

We reported a case of a spindle cell neoplasm in an infant, which was initially considered a vascular anomaly clinically and an eventual biopsy revealed marked inflammation with a spindle cell component that was resolved as an infantile fibrosarcoma with an ETV6 break-apart.

CONCLUSION

The context of this case lead to a further consideration of various other spindle cell neoplasms arising predominantly in the soft tissues during the infancy period as defined by the first two years of age. Though sharing similar morphologic features, these tumors can be categorized into several molecular genetic groups, which have provided both diagnostic and pathogenetic insights as well as treatment options in some cases.

Pediatric Non-Rhabdomyosarcoma Soft Tissue Sarcomas: Standard of Care and Treatment Recommendations from the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG)

This paper describes the standard of care for patients with non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) and the therapeutic recommendations developed by the European paediatric Soft tissue sarcoma Study Group (EpSSG). NRSTS form a very mixed group of mesenchymal extraskeletal malignancies. Their rarity, heterogeneity, and aggressiveness make the management of children and adolescents with these tumors complex and challenging. The overall cure rate for patients with NRSTS is around 70%, but survival depends on several prognostic variables, such as histotype and tumor grade, extent of disease and stage, tumor size, and tumor site. While surgery remains the mainstay of treatment for most of these tumors, a multimodal therapeutic approach including radiotherapy and chemotherapy is required in many cases. The EpSSG NRSTS 2005 study was the first prospective protocol tailored specifically to NRSTS. Together with the ARST0332 study developed by the North-American Soft Tissue Sarcoma Committee of the Children's Oncology Group (COG), the EpSSG NRSTS 2005 study currently represents the benchmark for these tumors, establishing risk-adapted standards of care. The EpSSG has developed common treatment recommendations for the large group of adult-type NRSTS (including synovial sarcoma), and specific treatment recommendations for other particular adult-type histologies (ie, alveolar soft-part sarcoma, clear cell sarcoma and dermatofibrosarcoma protuberans); other highly malignant tumors with a biology and clinical behavior differing from those of adult-type NRSTS (ie, rhabdoid tumors and desmoplastic small round cell tumor); and soft tissue tumors of intermediate malignancy (ie desmoid-type fibromatosis, inflammatory myofibroblastic tumors, and infantile fibrosarcoma). New effective drugs are needed for patients whose NRSTS carries the worst prognosis, ie, those with unresectable tumors, metastases at diagnosis, or relapsing disease. Progress in this area relies on our ability to develop international integrated prospective collaborations, both within existing pediatric oncology networks and, importantly, between the communities of specialists treating pediatric and adult sarcoma.

Treatment, pathological characteristics, and prognosis of pulmonary inflammatory myofibroblastic tumor–a retrospective study of 8 cases

Objective

Inflammatory myofibroblastic tumor (IMT) is a rare disease. We reviewed data from eight patients diagnosed with pulmonary IMT (PIMT) at our hospital with the aim of summarizing and analyzing the characteristics of PIMT to improve our understanding of the disease.

Methods

From January 2012 to December 2019, eight patients underwent surgical intervention for PIMT at The First Affiliated Hospital of Bengbu Medical College. Resected tumors were subjected to pathological and immunohistochemical analyses. The follow-up duration for all patients ranged from 2 years and 3 months to 9 years and 9 months (median: 6 years and 9 months).

Results

The male:female ratio was 5:3, and the mean age was 48.50 years (21–74 years). Two patients (25%) with lung disease discovered via chest computed tomography during physical examinations had not experienced any symptoms. Six patients (75%) presented at the hospital because of cough, expectoration, blood in sputum, and chest tightness. Lesions from all eight patients were surgically removed, and PIMT was confirmed based on pathological examinations and immunohistochemical results. No patient received additional treatment after discharge. All cases have been followed up to the time of writing, without any tumor recurrence or distant metastasis.

Conclusion

The age of onset of PIMT is usually over 40 years, and its clinical symptoms are easily confused with those of lung cancer. PIMT can only be diagnosed by histopathology and immunohistochemistry. Complete surgical resection is the preferred treatment, as patients undergoing surgery require no additional treatment, such as chemotherapy, and the survival rate is good.

Inflammatory Myofibroblastic Tumor: A Multi-Institutional Study from the Pediatric Surgical Oncology Research Collaborative

Inflammatory myofibroblastic tumor (IMT) is a mesenchymal neoplasm of intermediate malignancy. We describe the largest cohort of IMT patients to date, aiming to further characterize this rare, poorly understood tumor. This is a multi-institutional review of IMT patients ≤39 years, from 2000-2018, at 18 hospitals in the Pediatric Surgical Oncology Research Collaborative. 182 patients were identified with median age of 11 years. 33% of tumors were thoracic in origin. Presenting signs/symptoms included pain (29%), respiratory symptoms (25%), and constitutional symptoms (20%). Median tumor size was 3.9 cm. Anaplastic lymphoma kinase (ALK) overexpression was identified in 53% of patients. 7% of patients had distant disease at diagnosis. 91% of patients underwent resection: 14% received neoadjuvant treatment and 22% adjuvant treatment. 12% of patients received an ALK inhibitor. 66% of surgical patients had complete resection, with 20% positive microscopic margins, and 14% gross residual disease. Approximately 40% had en bloc resection of involved organs. Median follow-up time was 36 months. Overall 5-year survival (OS) was 95% and 5-year event-free survival (EFS) was 80%. Predictors of recurrence included respiratory symptoms, tumor size, and distant disease. Gross or microscopic margins were not associated with recurrence, suggesting that aggressive attempts at resection may not be warranted. This article is protected by copyright. All rights reserved.

Cutaneous Inflammatory Myofibroblastic Tumor with CARS-ALK Fusion: Case Report and Literature Review

Cutaneous inflammatory myofibroblastic tumors (IMT) constitute a rare entity, generating a diagnostic pitfall when diagnosing spindle cell proliferation within the dermis. Raising awareness of this tumor among dermatopathologists remains vital in differentiating it from common cutaneous tumors such as fibrous histiocytoma, atypical fibroxanthoma, melanoma, poorly differentiated carcinoma, and other more aggressive tumors. Accurate diagnosis of IMT aid in ensuring appropriate management and follow-up for patients while preventing unnecessary harm and overtreatment. Here we report a case of a 38-year-old female with a painless, slow-growing nodule of the left posterior scalp initially diagnosed as a dermatofibroma. The histological examination revealed an ill-defined dermal nodule of spindled cells without connection or infiltration of the epidermis. At high power, the cells were arranged in fascicles with a prominent background of lymphocytic infiltrate. Immunohistochemical analysis showed strong diffuse immunoreactivity for anaplastic lymphoma kinase (ALK), targeted RNA sequencing identified a CARS-ALK fusion ultimately confirming the accurate diagnosis of a cutaneous IMT. This article is protected by copyright. All rights reserved.

Clinical, pathologic, and molecular features of inflammatory myofibroblastic tumors in children and adolescents

BACKGROUND

Inflammatory myofibroblastic tumors (IMT) are rare, intermediate malignant tumors harboring frequent somatic molecular rearrangements. The management of IMT has not been standardized.

METHODS

A retrospective multicenter study was conducted on all pediatric patients treated for IMT between 2000 and 2019.

RESULTS

This series included 39 cases of IMT, with a median age at diagnosis of 7 years (range 20 days to 16 years). Tumor location included pelvis-abdomen (n = 16), thorax (n = 14), head and neck (n = 7), and limbs (n = 2). One patient had metastatic disease. Immunochemistry showed 21/39 (54%) anaplastic lymphoma kinase (ALK)-positive tumors. Somatic tyrosine kinase rearrangement was present in 31/36 (86%) of the tumors analyzed: 21 ALK, five ROS1, and five NTRK. Immediate surgery was performed in 24 patients (62%), with adjuvant therapy for three patients. Delayed surgery after neoadjuvant therapy was possible in 10 cases. Exclusive systemic therapy was delivered to four patients; one patient with orbital IMT was managed by watchful waiting. After a median follow-up of 33 months (range 5-124), eight (20%) recurrences/progressions occurred after surgery (seven after primary surgery and one after delayed surgery), after a median interval of 7 months (range 2-21), all in thoracic locations. The 3-year overall and disease-free survivals were 96.8% (95% CI: 79.2%-94.0%) and 77.4% (95% CI: 59.6%-88.1%), respectively. Relapses/progressions were more common in patients with a thoracic primary (p < .001) or after incomplete surgery with no adjuvant therapy (p = .027).

CONCLUSION

Surgery is effective in most cases of pediatric IMT. Systematic analysis of tyrosine kinase rearrangement is recommended. When the tumor is deemed only partially resectable to preserve organs and function, neoadjuvant therapy may be proposed to allow adequate conservative surgery.

What do we know about inflammatory myofibroblastic tumors? - A systematic review

BACKGROUND

Inflammatory myofibroblastic tumors (IMTs) are rare intermediate-grade neoplasms that have a high recurrence rate after excision and exhibit low metastatic potential. These tumors contain proliferating neoplastic, fibroblastic and myofibroblastic cells, and are also characterized by chronic inflammatory infiltration by lymphocytes, plasma cells, eosinophils, and histiocytes. They belong to the group of inflammatory spindle cell lesions. Some reactive lesions, such as inflammatory pseudotumors, may appear to be IMTs, which makes their differential diagnosis extremely difficult. The aim of this article is to compile the recent information on IMTs to aid in their diagnosis and treatment.

METHODS

We reviewed articles published between 2017 and 2021, which were selected from online medical databases. In addition, some earlier articles and latest scientific monographies were analyzed.

RESULTS

The terminology used for inflammatory spindle cell lesions seems to be confusing. The terms "inflammatory myofibroblastic tumors" and "inflammatory pseudotumors" are interchangeably used by many scientists. However, a detailed analysis of the development of terminology suggests that the term "inflammatory myofibroblastic tumors" should be used to refer to a neoplastic lesion.

CONCLUSIONS

IMTs are rare neoplasms, which have not been investigated in detail due to the difficulty in collecting a large number of cases. Thus, our knowledge about this disease remains unsatisfactory. Recently developed techniques such as next-generation sequencing and computer-aided histopathological diagnosis may be useful in understanding the etiopathology of IMTs, which will help in the selection of the most appropriate therapy for patients.

Treatment of Pediatric Inflammatory Myofibroblastic Tumor: The Experience from China Children’s Medical Center

Background: Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor with intermediate malignancy that tends to affect children primarily. To date, no standardized therapies exist for the treatment of IMT. This study aimed to share experience from China Children’s Medical Center for the explorative treatment of IMT. Methods: Patients with newly diagnosed IMT between January 2013 and December 2018 were included. Patients were grouped according to surgical margins and Intergroup Rhabdomyosarcoma Study Group (IRSG) staging. The clinical characteristic, therapeutic schedules, treatment response and clinical outcome were described. Results: Six patients were enrolled in this study, including two boys and four girls, with a median age of 57 months (range 10–148 months). Among them, five patients were anaplastic lymphoma kinase positive. Four patients achieved complete remission and two patients attained partial remission after treatment with this protocol. All patients were alive after a median follow-up of 4 years (range 3–7 years). The most common treatment-related adverse reaction was myelosuppression. Conclusion: In this study, we demonstrated that IMT has a good prognosis and the treatment selected according to risk stratification was effective and feasible.

A clinical signature predicting the malignant transformation of inflammatory myofibroblastic tumor in the head and neck

BACKGROUND

Inflammatory myofibroblastic tumors in the head and neck (HNIMTs) sometimes show aggressive clinical features and can be diagnosed as HNIMT with malignant transformation.

METHODS

The clinicopathological features of 45 HNIMTs with or without malignant transformation were retrospectively investigated. Logistic regression and receiver operating characteristic analysis were used to establish the predictive model.

RESULTS

HNIMT with malignant transformation was associated with worse prognosis. HNIMT with a tumor size of >4.4 cm, tumors located in the maxillary sinus, or a preoperative neutrophil-to-lymphocyte ratio (NLR) greater than 1.958 were associated with higher chance of malignant transformation, with an AUC value of 0.9189. Postoperative radiotherapy could benefit HNIMT patients with high risk of malignant transformation.

CONCLUSIONS

HNIMT patients with a tumor size of >4.4 cm, tumors located in the maxillary sinus, and a preoperative NLR over 1.958 were associated with a higher risk of malignant transformation. These patients can benefit from postoperative radiotherapy.

Paediatric Gastrointestinal, Hepatic and Pancreatic Inflammatory Myofibroblastic Tumours, A Single Centre Experience

ABSTRACT

Inflammatory myofibroblastic tumours (IMTs) are rare soft tissue tumours. Reports of gastrointestinal tract, liver and pancreas tumours are limited. The objective of this study is to identify presenting features, contributing prognostic / etiological factors and any variability in outcomes in the context of different historical treatments. We retrospectively reviewed the records of seven children treated at our hospital between 2006 and 2019 and assessed the demographic, presentation, treatment, immunohistochemistry, and outcomes of their tumours. Age range at presentation was 4 months-15 years with a male predominance. Presentations were typically due to local mass effect or incidental discovery. Systemic symptoms were rare. Outcomes were good with six out of seven stable or in remission irrespective of treatment. Surgical resection where possible is the treatment of choice. Medical therapy had good outcomes with chemotherapy acting as first line treatment when required. The only negative prognostic factor identified was local spread at the time of presentation.

Case Report: Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Application in Intraperitoneally Disseminated Inflammatory Myofibroblastic Tumor and in the Youngest Patient in the World: New Indication and Modification of Technique

Introduction: Peritoneal metastases occur in cancers that spread to the peritoneal cavity and indicate the advanced stage of the disease. In children they are mainly seen in sarcomas, Gastrointestinal Stromal Tumors and primary disseminated ovarian tumors. Inflammatory Myofibroblastic Tumor (IMT) is a very rare lesion, characterized by an unpredictable clinical course. The absorption of chemotherapeutic agents through the peritoneal-plasma barrier (PPB) is minimized, thus HIPEC procedure limits the systemic exposure to chemotherapy and permits the administration of its higher doses. The main purpose of HIPEC is to remove the visible macroscopic disease in order to achieve complete cytoreduction (CRS).

HIPEC Procedure in Children: Several papers deal with the CRS and HIPEC in children and adolescents, however pediatric experience is still limited. Thus far, the HIPEC procedure has been carried out on patients over 2 years old. The most common indication for the surgery and the best outcome was experienced by patients with desmoplastic small round cell tumor (DSRCT). Most patients received intraperitoneal cisplatin.

HIPEC Modification: A 5-month-old infant was admitted to the Department of Pediatric Oncology due to the abdominal distention and blood in the stool. The Computed Tomography (CT) revealed a solid-cystic mass in the right abdominal area. The primary tumor and numerous peritoneal metastasis were removed and the Inflammatory Myofibroblastic Tumor (IMT) was diagnosed. The patient underwent subsequently CRS and modified HIPEC procedure. To avoid overheating of the infant, the intraperitoneal normothermic chemoperfusion was performed. Due to the low body weight a modified dosage of intraperitoneal doxorubicin was used. The child underwent standard postoperative chemotherapy and received crizotinib therapy. At 12 months follow-up since treatment completion the patient remains in complete remission. To our knowledge this is the youngest patient, the only infant and the first pediatric patient with IMT who underwent the modified HIPEC procedure in the world.

Conclusions: CRS and HIPEC is technically possible also in infants. For its safe course patients selection and technique modification are necessary. Use of HIPEC should be also considered in intraperitoneally disseminated IMT. A complete cytoreductive surgery as the first HIPEC step seems to be the key factor in survival.

Inflammatory Myofibroblastic Tumor 12 Years After Treatment for Synovial Sarcoma: A Case Report

Inflammatory myofibroblastic tumors (IMTs) are mesenchymal neoplasms most seen in the abdominopelvic region, lung, and retroperitoneum; and less commonly seen in virtually any other site. We report a case of two lower limb masses consistent with diagnosis of IMTs. This is a 39-year-old woman with a history of right lower extremity popliteal fossa synovial sarcoma diagnosed 12 years prior and treated with chemotherapy, surgery, and radiation. She presented with two new - one anterior and one posterior - right thigh masses. Biopsies of the lesions demonstrated low-grade inflammatory spindle cell lesions at both sites. Wide resection was performed for both masses and further characterization of the surgical specimens was most consistent with IMT. At follow-up, the patient is well with no signs of recurrence 19 and 7 months postoperative to the resection of the anterior and posterior thigh masses, respectively. This case represents the first reported IMTs occurring as late as 12 years after primary cancer treatment, and the first occurring after synovial sarcoma.

Second Paediatric Strategy Forum for anaplastic lymphoma kinase (ALK) inhibition in paediatric malignancies: ACCELERATE in collaboration with the European Medicines Agency with the participation of the Food and Drug Administration

The first (2017) and sixth (2021) multistakeholder Paediatric Strategy Forums focused on anaplastic lymphoma kinase (ALK) inhibition in paediatric malignancies. ALK is an important oncogene and target in several paediatric tumours (anaplastic large cell lymphoma [ALCL], inflammatory myofibroblastic tumour [IMT], neuroblastoma and hemispheric gliomas in infants and young children) with unmet therapeutic needs. ALK tyrosine kinase inhibitors have been demonstrated to be active both in ALK fusion-kinase positive ALCL and IMT. ALK alterations differ, with fusions occurring in ALCL, IMT and gliomas, and activating mutations and amplification in neuroblastoma. While there are many ALK inhibitors in development, the number of children diagnosed with ALK driven malignancies is very small. The objectives of this ALK Forum were to (i) Describe current knowledge of ALK biology in childhood cancers; (ii) Provide an overview of the development of ALK inhibitors for children; (iii) Identify the unmet needs taking into account planned or current ongoing trials; (iv) Conclude how second/third-generation inhibitors could be evaluated and prioritised; (v) Identify lessons learnt from the experience with ALK inhibitors to accelerate the paediatric development of other anti-cancer targeted agents in the new regulatory environments. There has been progress over the last four years, with more trials of ALK inhibitors opened in paediatrics and more regulatory submissions. In January 2021, the US Food and Drug Administration approved crizotinib for the treatment of paediatric and young adult patients with relapsed or refractory ALCL and there are paediatric investigation plans (PIPs) for brigatinib and for crizotinib in ALCL and IMT. In ALCL, the current goal is to investigate the inclusion of ALK inhibitors in front-line therapy with the aim of decreasing toxicity with higher/similar efficacy compared to present first-line therapies. For IMT, the focus is to develop a joint prospective trial with one product in children, adolescents and adults, taking advantage of the common biology across the age spectrum. As approximately 50% of IMTs are ALK-positive, molecular analysis is required to identify patients to be treated with an ALK inhibitor. For neuroblastoma, crizotinib has not shown robust anti-tumour activity. A focused and sequential development of ALK inhibitors with very good central nervous system (CNS) penetration in CNS tumours with ALK fusions should be undertaken. The Forum reinforced the strong need for global academic collaboration, very early involvement of regulators with studies seeking possible registration and early academia-multicompany engagement. Innovations in study design and conduct and the use of 'real-world data' supporting development in these rare sub-groups of patients for whom randomised clinical trials are not feasible are important initiatives. A focused and sequenced development strategy, where one product is evaluated first with other products being assessed sequentially, is applicable for ALK inhibitors and other medicinal products in children.

Thoracic Multidetector Computed Tomography Evaluation of Inflammatory Myofibroblastic Tumor of the Lung in Pediatric Patients in the Era of Modern Diagnosis

PURPOSE

The purpose of this study was to investigate the characteristic thoracic multidetector computed tomography (MDCT) findings of pathologically proven inflammatory myofibroblastic tumor (IMT) of the lung in children in the era of modern understanding based on refined pathologic diagnosis.

MATERIALS AND METHODS

All pediatric patients (age 18 y and above) with a known pathologic diagnosis of IMT of the lung who underwent thoracic MDCT studies from May 2008 to December 2020 were included. Two pediatric radiologists independently evaluated thoracic MDCT studies for the presence of abnormalities in the lung (nodule, mass, cyst, ground-glass opacity, consolidation), pleura (pleural effusion, pneumothorax), and mediastinum and hilum (lymphadenopathy). When a lung abnormality was present, the number, size, composition (solid, cystic, or combination of both), location (laterality, lobar distribution, and intraparenchymal vs. pleural-based), borders (well-circumscribed vs. ill-defined), the presence and type of associated calcification (punctate, dense, curvilinear, or flocculent), the presence of associated cavitation, contrast enhancement pattern (homogeneous, heterogenous, central, or peripheral), and other associated findings (neural foramen involvement, anomalous vessels, mass effect, and invasion of adjacent thoracic structures) were also evaluated. Interobserver agreement between 2 independent reviewers was evaluated with κ statistics.

RESULTS

In all, 12 thoracic MDCT studies from 12 individual pediatric patients (5 males [42%] and 7 females [58%]; mean age: 9.9 y; SD: 4.4 y; range: 2 to 16 y) comprised the final study population. All 12 thoracic MDCT studies (100%) were performed with intravenous contrast. The most frequent MDCT finding of IMT of the lung in children is a solitary (92%), pleural-based (83%), well-circumscribed (100%), solid (92%) mass with heterogenous contrast enhancement (100%), often with dense calcification (50%), which occurred in both lungs and all lobes with similar frequency. No pleural abnormality (pleural effusion, pneumothorax) or mediastinal abnormality (lymphadenopathy) was detected. In addition, although mass effect on adjacent thoracic structures was frequently seen (42%), no invasion, neural foramen involvement, or associated anomalous vessels was identified. There was excellent interobserver κ agreement between 2 independent reviewers for detecting abnormalities on thoracic MDCT studies (κ>0.95).

CONCLUSIONS

IMT of the lung in children typically presents as a solitary, pleural-based, well-circumscribed, solid mass with heterogenous contrast enhancement, often with dense calcification, without significant laterality or lobar preference. In addition, pleural or mediastinal abnormalities are characteristically absent. These notable MDCT attributes of IMT of the lung are an important and novel finding, with great potential to help differentiate pediatric IMT of the lung from other thoracic masses in children.

Long-term efficacy update of crizotinib in patients with advanced, inoperable inflammatory myofibroblastic tumour from EORTC trial 90101 CREATE

PURPOSE

European Organisation for Research and Treatment of Cancer (EORTC) 90101 (CREATE) was a prospective, multicentric, non-randomised, open-label phase II basket trial to assess the efficacy and safety of crizotinib in patients with different types of cancers, including advanced inflammatory myofibroblastic tumour (IMT) with or without anaplastic lymphoma kinase (ALK) rearrangements. Here, we report updated results with long-term follow-up.

PATIENTS/METHODS

After central reference pathology, eligible ALK-positive and ALK-negative patients with advanced/metastatic IMT deemed incurable with surgery, radiotherapy or systemic therapy received oral crizotinib 250 mg twice daily. The ALK status was assessed centrally using immunohistochemistry and fluorescence in situ hybridisation. The primary end-point was the proportion of patients who achieved an objective response (i.e. complete or partial response). If ≥6 ALK-positive patients achieved a confirmed response, the trial would be deemed successful.

RESULTS

At data cut-off on 28th January 2021, we performed the final analysis of this trial. Of the 20 eligible and treated patients (19 of whom were evaluable for efficacy), with a median follow-up of 50 months, five were still on crizotinib treatment (4/12 ALK-positive and 1/8 ALK-negative patients). The updated objective response rate (ORR) was 66.7% (95% confidence interval [CI] 34.9-90.1%) in ALK-positive patients and 14.3% (95% CI 0.0-57.9%) in ALK-negative patients. In the ALK-positive and ALK-negative patients, the median progression-free survival was 18.0 months (95% CI 4.0-NE) and 14.3 months (95% CI 1.2-31.1), respectively; 3-year overall survival rates were 83.3% (95% CI 48.2-95.6) and 34.3% (95% CI 4.8-68.5). Safety results were consistent with previously reported data.

CONCLUSION

These updated results confirm previous findings that crizotinib is effective, with durable responses, in patients with locally advanced or metastatic ALK-positive IMT. With further follow-up after the original primary analysis, the ORR increased, as patients derived long-term benefit and some responses converted from stable disease to partial responses.

CLINICAL TRIAL NUMBER

EORTC 90101, NCT01524926.

Complicated course of biliary inflammatory myofibroblastic tumor mimicking hilar cholangiocarcinoma: A case report and literature review

BACKGROUND

The inflammatory myofibroblastic tumor (IMT) is a rare, idiopathic, usually benign, mass-forming disease with myofibroblastic proliferation and a varying amount of inflammatory cells. Although it can affect various organs, the biliary tract is a rare localization of primary IMT, clinically, endoscopically and radiologically imitating cholangiocarcinoma. The treatment options are based only on clinical practice experience.

CASE SUMMARY

A 70-year-old woman was referred to our center due to progressive fatigue, weight loss, abdominal pain, night sweats, and elevated liver enzymes. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography (ERCP) revealed proximal common hepatic duct and hilar biliary strictures extending bilaterally to lobular bile ducts. Although initial clinical, endoscopic and radiological signs were typical for hilar cholangiocarcinoma, histological examination showed no signs of malignancy. In total, 8 biopsies using different approaches were performed (several biopsies from dominant stricture during ERCP and direct cholangioscopy; ultrasound-guided liver biopsy; diagnostic laparoscopy with liver and lymph node biopsies). Histological examination revealed signs of IMT, and the final diagnosis of biliary IMT was stated. Although IMT is usually a benign disease, in our case, it was complicated. All pharmacological treatment measures were ineffective. The patient still needs permanent stenting, suffers from recurrent infections and mechanical jaundice. Despite that, the patient already survived 24 mo.

CONCLUSION

IMT presenting with hilar biliary strictures is a unique diagnostic and clinical challenge as it is indistinguishable from cholangiocarcinoma, and there are no evidence-based treatment options. Our goal is to increase the understanding of this rare disease and its possible course.

Inflammatory myofibroblastic tumor: molecular landscape, targeted therapeutics, and remaining challenges

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumor of intermediate malignant potential that predominantly affects children, adolescents and young adults. IMT has a predilection for the lung, abdomen, pelvis, and retroperitoneum, however, can affect any part of the body. IMT is typically localized, and multifocal or metastatic disease is uncommon. Complete surgical resection is the treatment of choice when feasible. There is no established standard of care for unresectable and advanced IMT. Approximately half of IMTs harbor anaplastic lymphoma kinase (ALK) gene rearrangements, and fusions involving ROS1, PDGFRβ, RET and NTRK have also been described. Given the molecular landscape of IMT, management of these tumors has evolved to include tyrosine kinase inhibitors and novel targeted therapeutics. This review highlights the molecular characteristics, evolution of targeted therapies and the remaining challenges in the management of IMT.