Epithelioid inflammatory myofibroblastic sarcoma of stomach: diagnostic pitfalls and clinical characteristics

Pei Xu; Pingping Shen; Yangli Jin; Li Wang; Weiwei Wu

Epithelioid inflammatory myofibroblastic sarcoma of stomach: diagnostic pitfalls and clinical characteristics

Int J Clin Exp Pathol. 2019 May 1;12(5):1738-1744. eCollection 2019.

Authors

Pei Xu¹, Pingping Shen², Yangli Jin³, Li Wang⁴, Weiwei Wu¹

Affiliations

¹ Department of Burns, Ningbo Huamei Hospital, University of Chinese Academy of Science (Ningbo No. 2 Hospital) Ningbo, China.
² Department of Gastroenterology, Yinzhou Second Hospital Ningbo, China.
³ Department of Ultrasonography, Yinzhou Second Hospital Ningbo, China.
⁴ Department of Pathology, Clinical Pathological Diagnosis Center Ningbo, China.

PMID: 31933992
PMCID: PMC6947137

Abstract

Inflammatory myofibroblastic tumor (IMT) is a neoplasm composed of spindled neoplastic myofibroblasts admixed with reactive lymphoplasmacytic cells, plasma cells, and/or eosinophils, which has an intermediate biological behavior. An IMT variant with plump round epithelioid or histiocytoid tumor cells, recognized as epithelioid inflammatory myofibroblastic sarcoma (EIMS), has a more clinically aggressive progression. To the best of our knowledge, only about 40 cases of EIMS have previously been reported in limited literature. Here, we report here a case of unusual EIMS with a relative indolent clinical behavior. We reviewed the literature for 18 similar cases. The patients present with a highly aggressive inflammatory myofibroblastic tumor characterized by round or epithelioid morphology, prominent neutrophilic infiltrate, and positive staining of ALK with RANBP2-ALK gene fusion or RANBP1-ALK gene fusion, or EML4-ALK gene fusion. Our case is the first case of primary stomach EIMS. Moreover, the mechanisms of the rare entity have not been widely recognized and require further study. Early accurate diagnosis and complete resection of this tumor is necessary. Some researchers suggest expression of PD-L1 may provide new strategies for ALK-targeted therapy.

Keywords: Inflammatory myofibroblastic tumor; RANBP1-ALK gene fusion; RANBP2-ALK gene fusion; epithelioid inflammatory myofibroblastic sarcoma; immunostaining; morphology; poor prognosis.