Seoro Park, Soyoung Jeung, Yewon Ji, Matti Kiupel, Kichang Lee, Hakyoung Yoon
Background
Gastric plasmacytomas are extremely rare in dogs, representing less than 1% of gastric tumors. Clinical signs are often nonspecific, making diagnosis challenging. Although imaging plays a crucial role in identifying gastric masses, detailed ultrasonographic (AUS) and computed tomographic (CT) features of plasmacytomas have not been well described in veterinary literature. This report contributes two additional cases to the scant existing documentation, aiming to clarify their imaging characteristics.
Methods
Two canine cases (a Pomeranian and a Maltese) underwent abdominal ultrasonography and contrast-enhanced CT to evaluate gastric masses. Imaging findings were correlated with surgical resection and histopathological analysis. Pre- and post-contrast Hounsfield unit (HU) measurements were taken, and ultrasound Doppler was used to assess vascularity. Histological confirmation of plasmacytoma was obtained in both cases.
Results
Both dogs presented with solitary, round gastric masses located in the pyloric antrum or greater curvature. AUS findings showed variable echogenicity, partial wall-layer disruption, and peripheral vascularity. CT revealed transmural masses with strong post-contrast enhancement (>40 HU difference), suggestive of submucosal or muscularis origin. One mass exhibited heterogeneous enhancement and ulceration; the other had homogeneous enhancement. Histopathology confirmed plasmacytoma in both cases, with ulceration documented histologically in one. No immediate postoperative complications occurred.
Limitations
The study is limited by its case-report nature and small sample size. No histological evaluation was performed on enlarged lymph nodes or other organs, limiting the ability to assess metastasis. Additionally, arterial-phase CT was not included, and immunohistochemistry to rule out B-cell lymphoma was not performed. These factors limit definitive tumor classification and metastatic assessment.
Conclusions
Gastric plasmacytomas in dogs, although rare, should be considered in the differential diagnosis of solitary, well-demarcated, contrast-enhancing gastric masses, particularly in the pyloric antrum or greater curvature. AUS and CT can provide critical preoperative clues, but histopathology and immunohistochemistry remain essential for definitive diagnosis. Recognition of specific imaging patterns may improve early detection and clinical decision-making.
Abdominal ultrasound (A) and post-contrast computed tomography (CT) images (B–D) of a mass in the pyloric antrum in Case 1. (A) On ultrasound, a mixed echogenic mass (arrowhead) attached to the gastric wall, narrowed pyloric lumen (*), hypoechoic area indicating necrosis or hemorrhage (arrow), and hyperechoic content suggestive of ingesta (dotted arrow). (B–D) Post-contrast CT images of the mass (arrowhead) in transverse (B), sagittal (C), and dorsal (D) planes. The mass (arrowhead) shows continuity with both inner and outer gastric wall layers, suggesting transmural involvement, with heterogeneous contrast enhancement. Disrupted mucosal continuity in the pyloric region (arrow) suggests ulceration.
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