Clinicopathological analysis of epithelioid inflammatory myofibroblastic sarcoma

Abstract

Abstract. Inflammatory myofibroblastic tumor (IMT) is a distinctive neoplasm composed of myofibroblastic and fibroblastic spindle cells, accompanied by the inflammatory infiltration of plasma cells, lymphocytes and/or eosinophils. Epithelioid inflammatory myofibroblastic sarcoma (EIMS), which primarily consists of cells with a round or epithelioid morphology, is associated with a poor prognosis and rapid development of local recurrence, and has been recognized to be a variant of IMT. Diagnosis of EIMS is difficult owing to its close resemblance to malignant mesothelioma, anaplastic large cell lymphoma, gastrointestinal stromal tumor and other malignant diseases. In the present study, a case of this rare tumor was evaluated in a 26-year-old male who was admitted to hospital after experiencing abdominal pain for ~18 days and abdominal distention for 1 week. The patient's tumor was examined by imaging, gross examination, histology, immunohistochemistry and fluorescence in situ hybridization (FISH). The magnetic resonance imaging enhanced-scanning image revealed that the morphology of the tumor was irregular, and signal was medley consisting of high and low hybrid reinforcement. Tumors were located in the bladder and rectal pit, in the lower part of the lower abdomen, indicating the presence of malignancy and involvement of the small intestine and rectum. Enhanced-scanning imaging revealed notable inhomogeneous enhancement. Gross examination revealed that the tumor was solid and had a variegated appearance with alternating fleshy and mucoid areas in the cut surface. Microscopically, the tumors were dominated by sheets of epithelioid-to-round cells with a prominent inflammatory infiltrate. The majority of the stroma was myxoid. Immunohistochemically, the tumor cells exhibited diffuse strong staining for ALK receptor tyrosine kinase (hereafter ALK), vimentin, tumor protein P53, desmin, Wilms' tumor 1 and programmed death-ligand 1. FISH analysis also revealed the existence of ALK rearrangement. The expression of PD-L1 in EIMS indicates that the immune checkpoint blockade could represent a novel therapy for the treatment of EIMS.

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

“…EIMS is a rare variant of IMT, which is clinically distinct from conventional cases in that it follows an aggressive clinical course and has a high mortality rate ( 6 ). EIMS predominantly originates intraabdominally, with most cases arising in the omentum and mesentery, and adult males appear to be more susceptible to EIMS ( 7 ). There are some common features observed in patients with EIMS, including round-to-epithelioid tumor cells, abundant myxoid stroma with inflammatory infiltrates composed primarily of neutrophils, immuno-positivity for nuclear membrane ALK staining, RANBP2-ALK gene fusion and Des positive staining ( 7 , 8 ).…”

“…EIMS predominantly originates intraabdominally, with most cases arising in the omentum and mesentery, and adult males appear to be more susceptible to EIMS ( 7 ). There are some common features observed in patients with EIMS, including round-to-epithelioid tumor cells, abundant myxoid stroma with inflammatory infiltrates composed primarily of neutrophils, immuno-positivity for nuclear membrane ALK staining, RANBP2-ALK gene fusion and Des positive staining ( 7 , 8 ). In IMTs, inflammatory infiltrates are composed primarily of plasma cells and lymphocytes ( 3 ), immuno-positive staining for ALK expression is predominantly observed in the cytoplasm and membrane ( 9 ), and SMA expression is more commonly observed than Des ( 3 ).…”

“…Although the prognosis of patients with EIMS is poor, there are still a few cases of successful remission with a sustained response to the ALK inhibitor crizotinib ( 10 ). Furthermore, programmed cell death 1 ligand 1 expression has been detected in patients with EIMS ( 7 ). Therefore, whether immune checkpoint blockade may serve as a novel therapeutic approach for treatment of EIMS should be studied further.…”

“…Epithelial inflammatory myofibroblast sarcoma (EIMS), a rare malignant variant of IMT, requires aggressive clinical measures, since patients with EIMS often exhibit rapid local recurrence, and the disease is associated with a high mortality rate ( 6 ). At present, only isolated case reports of EIMS exist due to its rarity ( 7 – 10 ).…”

Epithelioid inflammatory myofibroblastic sarcoma: the youngest case reported

“…2 It is often intra-abdominal and clinicopathologically different from conventional IMT in that it is more aggressive with a higher rate of recurrence and poorer prognosis. 3 It is mainly composed of plump round to epithelioid or histiocytoid tumor cells with a minor spindle cell component. Cells are arranged in clusters or non-cohesive sheets within a stroma, which is frequently myxoid.…”