Inflammatory myofibroblastic tumor arising from soft tissues of extremities harboring a novel CLIP2-ALK fusion

A Novel CASC15-ALK and TFG-ROS1 Fusion Observed in Uterine Inflammatory Myofibroblastic Tumor

The majority of inflammatory myofibroblastic tumors (IMTs) in the gynecologic tract occur in the uterine corpus and harbor anaplastic lymphoma kinase ( ALK ) rearrangement. Herein, we report 1 uterine IMT case with a novel fusion involving ALK and 1 uterine IMT case with ROS1 rearrangement. The ages of the patients were 56 and 57 yr, respectively. The tumor size was 10.0 and 8.0 cm, respectively. Both patients had stage IB disease. Histologically, the 2 IMT cases had classic morphologic features and predominantly comprised bland spindle cells with hypercellular (fascicular/storiform) and hypocellular (myxoid rich) areas admixed with variably prominent lymphoplasmacytic infiltration. Immunohistochemically, the ALK -rearranged case was positive for ALK , and the ROS1 -rearranged case was positive for ROS1 . Both cases were diffusely positive for desmin. The tumor cells were variably positive for estrogen receptor (1/2 cases, 50.0%) and progesterone receptor (1/2 cases, 50.0%). Targeted RNA sequencing revealed one case each with either a novel CASC15-ALK or TFG-ROS 1 fusion. We identified a novel ALK fusion partner CASC15 in IMT and described the first uterine IMT with a TFG-ROS1 fusion. This study improves our understanding of molecular events in IMT.

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.

Clinical characteristics and outcomes of 17 cases of inflammatory myofibroblastic tumor at a University Hospital in China

The aim of the present study was to explore the clinical and pathological characteristics, diagnosis, and treatment of inflammatory myofibroblastic tumor (IMT). A total of 17 patients with IMT diagnosed between July 2010 and February 2020 were included in the present study, and the clinical characteristics, pathological features, treatment and prognosis were analyzed retrospectively. The cohort consisted of 17 participants, including 12 men and 5 women, with a mean age of 34.76 years. The most common locations of tumors were the bronchi and the lungs (9 cases, including 1 case involving the mediastinum), followed by the colon and bladder (2 cases each), and the omentum majus, mesocolon, stomach and peritoneal cavity (1 case each). Immunohistochemical staining demonstrated that the tumor cells exhibited positive staining for anaplastic lymphoma kinase p80 (13/17), smooth muscle actin (12/17), cytokeratin pan (6/17), vimentin (5/17) and desmin (4/17). The follow-up time was 18-114 months. A patient with epithelial inflammatory myofibroblast sarcoma (EIMS) succumbed to the disease, 1 case was lost to follow-up, 2 cases relapsed and the other 13 cases were considered cured. IMTs may be malignant or low-grade. EIMS is a rare and invasive variant of IMT. The clinical and imaging manifestations are often unique and vary among individuals. Once confirmed by pathology, radical surgery should be the first choice of treatment.