Primary Gastric Alveolar Rhabdomyosarcoma: A Potent Mimicker of Neuroendocrine Carcinoma.

Alveolar rhabdomyosarcoma (ARMS) is a malignant tumor with skeletal muscle differentiation that usually occurs in soft tissues of the extremities or trunk. To date, only a few cases of primary gastric ARMS have been reported. Herein, we describe a case of ARMS in a man in his 80s and present a literature review. A submucosal tumor-like lesion was detected endoscopically. Histologically, the tumor cells exhibited a poorly differentiated morphology with hyperchromatic nuclei. Neuroendocrine markers, such as synaptophysin and CD56, were positive, and neuroendocrine carcinoma (NEC) was considered a differential diagnosis. However, both myogenic markers and OLIG2, which reflect FAX3 or FAX7 fusion, were positive, leading to a diagnosis of ARMS. Primary gastric ARMS is an extremely rare condition. Better awareness of this entity and its similarity to NEC is necessary for appropriate diagnosis and treatment.
Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.
(Copyright © 2024, Okuno et al.)