Abstract Introduction/Objective Gastric glomus tumor (GGT) is a rare mesenchymal tumor that is challenging to diagnose, especially when the immunoprofile overlaps with other more common gastric mesenchymal tumors. The majority of GGT are benign, however, rarely it can be atypical or even malignant. Herein, we present a case of a young female with atypical gastric glomus tumor of uncertain malignant potential. Methods/Case Report A 16-year-old female presented to the emergency with abdominal pain, coffee ground emesis, and melena. Imaging showed a 3.2 cm well-defined gastric mass arising from the muscularis propria. Results (if a Case Study enter NA) The FNA biopsy revealed clusters of tumor cells with uniform characteristics, exhibiting distinct cell membranes and eosinophilic to clear cytoplasm, surrounding prominent vasculature. Immunohistochemical analysis showed that the tumor cells were positive for SMA, synaptophysin, vimentin, calponin, and caldesmon, with weak, patchy positivity for DOG1. CD34 highlighted the vessels separating the tumor cellular clusters into lobules. CD117 and Desmin were negative. The Ki67 proliferation index varied with hotspot foci 25-30%. Morphology and immunoprofile suggest glomus tumor, however, neuroendocrine tumor and epithelioid GIST needed to be excluded. Subsequent resection specimen showed that the tumor was located within the muscularis propria with extension into the serosal vessels, suggesting vascular invasion, along with foci of cellular spindling and nuclear irregularity are identified. No necrosis noted. Tumor cells were positive for cyclin D1 while negative for myogenin, chromogranin, and DOG1. Overall, findings were consistent with GGT of uncertain malignant potential. Conclusion Although GGT are rare, they should be considered in the differential diagnosis of gastric mesenchymal tumors. The presence of diffuse SMA staining can help distinguishing them from GIST. It is crucial to scrutinize for signs of cellular and nuclear atypia, particularly in deeply seated glomus tumors.
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