Inflammatory myofibroblastic tumor of the urinary bladder with FN1‑ALK gene fusion: A case report

Inflammatory myofibroblastic tumors (IMTs), which are rare tumors, exhibit myofibroblastic differentiation, often with anaplastic lymphoma kinase (ALK) gene rearrangements. A subset of IMTs identified in the urinary tract have been shown to harbor a fibronectin 1 (FN1)-ALK gene fusion. In this case report, a case of an IMT with FN1-ALK fusion in the urinary bladder was presented, and its clinicopathological characteristics were reviewed. A 45-year-old female was referred to Chungbuk National University Hospital with gross hematuria. Cystoscopy revealed a solid mass in the bladder. The patient subsequently underwent transurethral resection of the lesion. The mass comprised stellate and spindled myofibroblastic cells that were arranged in loose fascicles, with a myxoid background and a mixed inflammatory infiltrate. Immunohistochemical analysis revealed that the tumor cells were positive for vimentin, cytokeratin AE1/AE3 and ALK, and focal-positive for desmin. Targeted next-generation sequencing was subsequently employed to identify the FN1-ALK fusion. To date, the patient has undergone outpatient follow-up for 18 months, with no signs of tumor recurrence. To conclude, in total, FN1 has been identified as an ALK fusion partner almost exclusively in cases of genitourinary IMTs [13 bladder IMTs (including the present case) and two uterine IMTs]. In the present case, the FN1-ALK fusion was found to involve ALK exon 19 and FN1 exon 23. By contrast, the majority of the other IMTs with an ALK fusion have involved ALK exon 20, whereas ALK fusion involving ALK exon 18 or 19 has been reported only in genitourinary IMTs. Therefore, the FN1-ALK fusion involving ALK exon 18 or 19 may be specific to a subset of IMTs arising in the urinary bladder.

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.

[Immunohistochemical and molecular diagnosis of inflammatory myofibroblastic tumor of the uterus: a literature review and a clinical case]

Inflammatory myofibroblastic tumors of the uterus (uIMT) are rare and difficult to diagnose neoplasms, since the morphological characteristics of this tumor are not specific and are found in other pathological changes. In addition, until recently, specific uIMT markers have not been identified and their diagnostic standards not defined. However, in recent years, there have been more and more studies aimed to identify characteristic morphological, immunohistochemical, and molecular genetic features for the differential diagnosis of uIMT. Recent papers studying uIMT indicate anaplastic lymphoma kinase (ALK) as a potentially reliable marker of uIMT. This communication describes a clinical case of uIMT in a 40-year-old woman who has been preoperatively diagnosed with a large subserous interstitial myomatous nodule. The final diagnosis was made, by analysing a combination of morphological and immunohistochemical signs. This clinical case with a literature review is indicated to consider ALK as a key criterion in the diagnosis of uIMT, as well as the relationship between subsequent treatment and the presence of ALK in the studied tissues.

A case report of an inflammatory myofibroblastic tumor of the neck: A focus on the computed tomography and magnetic resonance imaging findings

Inflammatory myofibroblastic tumors (IMTs) of the neck are rare, with only a few patients reported in the literature. The present study discusses the clinical manifestations, radiographic characteristics and management of these tumors, with a focus on imaging modalities. A case of IMT of the neck is presented and the associated literature is reviewed. In total, seven patients in seven English-language studies, including the present case, and one patient in one Chinese-language study were found. On CT scans, all tumors appeared as soft-tissue densities. Upon magnetic resonance imaging (MRI), all tumors displayed a heterogeneous hypointense-isointense signal on T1-weighted sequences and an isointense-hyperintense signal on T2-weighted sequences. All tumors showed enhancement on enhanced CT and MR images. The imaging features of the neck IMTs can be summarized as follows: i) When enhanced, the tumor displays enhancement on CT and MR images; ii) MRI is superior to CT scans in the differential diagnosis of this disease; iii) in general, the lesion displays a hypointense-isointense signal on T1-weighted sequences and an isointense-hyperintense signal on T2-weighted sequences; iv) due to the fibrous tissue in the tumor, delayed enhancement may be observed on gadolinium-enhanced MR images; and v) due to its benign or intermediate features, the tumor is usually a well-defined mass.

Primary inflammatory myofibroblastic tumor of the trachea

Inflammatory myofibroblastic tumors (IMTs) are rare neoplasms that can involve the airway. Recent studies have shown their malignant behavior with local recurrence and potential metastatic spread; half of the cases are associated with anaplastic lymphoma kinase gene rearrangement. Complete surgical resection is recommended, when feasible. We present a case of a 26-year-old woman admitted to our institution with severe respiratory failure; she was affected with primary IMT of the trachea and underwent complete surgical resection.