A malignant inflammatory myofibroblastic tumor of the hypopharynx harboring the 3a/b variants of the EML4-ALK fusion gene

Case Report: Early Distant Metastatic Inflammatory Myofibroblastic Tumor Harboring EML4-ALK Fusion Gene: Study of Two Typical Cases and Review of Literature

Inflammatory myofibroblastic tumor (IMT) is a distinctive neoplasm that frequently arises in the lung and accounts for ~1% of lung tumors. Distant metastatic IMT is extremely rare and has been poorly investigated. This analysis was specifically performed to explore the clinicopathological and genetic features of early distant metastatic IMT. Two typical patients with distant metastatic IMTs were selected, which accounted for 1.13% of all diagnosed IMTs in the last 5 years. One patient was a 55 year-old male, and the other patient was a 56 year-old female. Both primary tumors arose from the lung, and the initial clinical symptoms of the two patients involved coughing. Both of the imaging examinations showed low-density nodular shadows in the lungs with enhancement around the mass. Microscopically, dense arranged tumor cells, prominent cellular atypia, and high mitotic activity with atypical form were more prominent in the metastatic lesions than in the primary lesions. All of the primary and metastatic tumors in both cases showed positive anaplastic lymphoma kinase (ALK) immunostaining and ALK rearrangement via fluorescence in situ hybridization. The EML4 (exon 6)-ALK (exon 20) fusion variant (v3a/b) was identified by using next-generation sequencing (NGS) and was verified by using reverse transcription polymerase chain reaction (RT-PCR). Furthermore, intronic variants of NOTCH1 and synonymous variants of ARAF were also detected via NGS in one IMT for the first time and were verified in all of the primary and metastatic lesions via PCR. Distant metastasis occurred during a short period of time (1 and 2 months) after the first surgery. One patient presented with multiple metastases to the subcutaneous tissue and bone that responded to ALK inhibitor alectinib therapy, and the tumor was observed to regress 10 months after the initial ALK inhibitor therapy. In contrast, the other patient presented with subcutaneous neck metastasis without ALK inhibitor treatment and succumbed to the disease within 3 months after the surgery. This study demonstrated the possible role of EML4-ALKv3a/b in the malignant progression of IMT and proposed certain therapeutic effects of ALK inhibitors on multiple metastatic IMTs.

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.

Inflammatory myofibroblastic tumor of bone harboring an ALK gene amplification

Inflammatory myofibroblastic tumor (IMT) is a neoplastic proliferation of myofibroblastic/fibroblastic cells with a variable admixture of inflammatory cells. It primarily affects soft tissue and viscera of children and young adults. IMT occurring in bone is extremely rare. Approximately 50% of IMTs carry a clonal rearrangement of the anaplastic lymphoma kinase (ALK) gene, while other receptor tyrosine kinase gene rearrangements have been seen in a small subset of IMT. Herein, we report the first case of IMT which harbors an ALK gene amplification rather than a rearrangement thus resulting in overexpression of the protein, arising from the femur of a 24-year-old man. Our case provides a novel pathogenesis for IMT. An overview of cytogenetic abnormalities of IMT is also integrated into this report.