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

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.

Abdominal inflammatory myofibroblastic tumour: Clinicopathological and molecular analysis of 20 cases, highlighting potential therapeutic targets

AIMS

Inflammatory myofibroblastic tumour (IMT) is a rare mesenchymal neoplasm of intermediate malignant potential, occurring at any age and at multiple sites. Epithelioid inflammatory myofibroblastic sarcoma (EIMS) is an aggressive subtype of IMT, typically involving the abdomen. Most IMTs harbour kinase gene fusions, especially involving ALK and ROS1, but 20-30% of IMTs show no detectable translocations. The aim of this study is to further delineate clinicopathological and molecular characteristics of abdominal IMT and discover potential new therapeutic targets.

METHODS AND RESULTS

In 20 IMTs, including four EIMS, RNA fusion analysis was performed, followed by multiplex DNA analysis if no ALK or ROS1 fusion was detected. Fourteen IMTs (70.0%) had an ALK translocation and the fusion partner was identified in 11, including a RRBP1::ALK fusion, not previously described in classical (non-EIMS) IMT. RANBP2::ALK fusion was demonstrated in all EIMS. One IMT had a ROS1 fusion. In all ALK/ROS1 translocation-negative IMTs mutations or fusions - as yet unreported in primary IMT - were found in genes related to the receptor tyrosine kinase (RTK)/PI3K/AKT pathway. Three of four patients with EIMS died of disease [mean survival 8 months (4-15 months)], whereas only one of 14 classical IMT patients succumbed to disease [mean follow-up time 52 months (2-204 months); P < 0.01].

CONCLUSION

This study shows the wide clinical spectrum of abdominal IMTs and affirms the poor prognosis of EIMS, raising discussion about its status as IMT subtype. Furthermore, the newly detected alterations of the RTK/PI3K/AKT pathway expand the molecular landscape of IMTs and provide potential therapeutic targets.

A rare huge bladder inflammatory myofibroblastic tumor treated by en bloc resection with diode laser: a case report and literature review

Background

Inflammatory myofibroblastic tumor (IMT) is a rare neoplasm with malignant potential. Bladder IMT is even rarer and mainly treated by surgical resection However, partial or radical cystectomy would affect the quality of life of patients due to major surgical trauma, and classical TURBT is hard to avoid intraoperative complications including obturator nerve reflex and bleeding etc. Therefore, the safe and effective better choice of surgical approaches become critical to bladder IMT.

Case presentation

A 42-year-old male patient was admitted to the department of urology with persistent painless gross hematuria for more than 10 days without the presentation of hypertension. Preoperative routine urine examination of red blood cells was 7738.9/HPF (normal range ≤ 3/HPF). CTU indicated a space occupying lesion (6.0 cm×5.0 cm) in the left posterior wall of the bladder with heterogeneous enhancement in the excretory phase. MRI also indicated bladder tumor with slightly equal SI on T1WI and mixed high SI on T2WI (6.0 cm×5.1cm×3.5cm) in the left posterior wall of the bladder. En bloc resection of bladder IMT with 1470 nm diode laser in combination of removing the enucleated tumor by the morcellator system was performed. Postoperative pathological examination revealed bladder IMT, with IHC positive for Ki-67 (15-20%), CK AE1/AE3, SMA, and Desmin of bladder IMT and negative for ALK of bladder IMT as well as FISH negative for ALK gene rearrangement. Second TUR with 1470 nm diode laser was performed within 6 weeks to reduce postoperative risk of recurrence due to highly malignant potential for the high expression of Ki-67 (15-20%) and negative ALK in IHC staining. The second postoperative pathology report showed chronic inflammation concomitant with edema of the bladder mucosa without bladder IMT, furthermore no tumor was observed in muscularis propria layer of bladder. No recurrence occurred during the period of 24-month follow-up.

Conclusion

En bloc resection of bladder IMT in combination of the following second transurethral resection with 1470 nm diode laser is a safe and effective surgical approach for the huge bladder IMT with highly malignant potential.

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.

An update on genomic aberrations in Spitz naevi and tumours

Spitz neoplasms continue to be a diagnostic challenge for dermatopathologists and are defined by distinctive morphological and genetic features. With the recent advancements in genomic sequencing, the classification, diagnosis, and prognostication of these tumours have greatly improved. Several subtypes of Spitz neoplasms have been identified based on their specific genomic aberrations, which often correlate with distinctive morphologies and biological behaviour. These genetic driver events can be classified into four major groups, including: (1) mutations [HRAS mutations (with or without 11p amplification) and 6q23 deletions]; (2) tyrosine kinase fusions (ROS1, ALK, NTRK1-3, MET and RET); (3) serine/threonine kinase fusions and mutations (BRAF, MAP3K8, and MAP2K1); and (4) other rare genomic aberrations. These driver genomic events are hypothesised to enable the initial proliferation of melanocytes and are often accompanied by additional genomic aberrations that affect biological behaviour. The discovery of theses genomic fusions has allowed for a more objective definition of a Spitz neoplasm. Further studies have shown that the majority of morphologically Spitzoid appearing melanocytic neoplasms with aggressive behaviour are in fact BRAF or NRAS mutated tumours mimicking Spitz. Truly malignant fusion driven Spitz neoplasms may occur but are relatively uncommon, and biomarkers such as homozygous 9p21 (CDKN2A) deletions or TERT-p mutations can have some prognostic value in such cases. In this review, we discuss the importance and various methods of identifying Spitz associated genomic fusions to help provide more definitive classification. We also discuss characteristic features of the various fusion subtypes as well as prognostic biomarkers.

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.

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.