Case Report

A 58-year-old man was referred for upper endoscopy during preoperative evaluation for bariatric surgery. His history included grade III obesity (BMI 36 kg/m²), obstructive sleep apnea on CPAP therapy, hypertension, active smoking (43 pack-years) and alcohol use disorder. Family history was notable for colorectal cancer in his mother and bladder cancer in his father. Laboratory tests and abdominal ultrasound were unremarkable except for hepatic steatosis.

Upper endoscopy revealed a 25-mm subepithelial lesion in the gastric antrum with a central erosion. Endoscopic ultrasound (EUS) demonstrated an 18-mm heterogeneous, predominantly avascular lesion apparently arising from the submucosal layer with possible focal perigastric extension. Additionally, a second hypoechoic mass >50 mm was identified in the gastric body, showing a predominantly blue elastographic pattern and close contact with the pancreatic head.

Contrast-enhanced computed tomography showed thickening along the lesser curvature with a 58×33-mm mass extending to adjacent fat planes without a clear cleavage plane with the pancreas. A second smaller antral lesion and multiple enlarged perigastric lymph nodes were present. Peritoneal nodules suggestive of carcinomatosis were also noted. Given the atypical imaging pattern, EUS-guided fine-needle biopsy was performed for histologic diagnosis.

What is the most likely diagnosis?

Submeter

Discussion

This case highlights the diagnostic challenges posed by gastric subepithelial lesions and the pivotal role of endoscopic ultrasound-guided tissue acquisition. Gastrointestinal lymphomas are uncommon, and gastric involvement may represent either primary disease or secondary dissemination. Imaging findings frequently overlap with other malignancies, particularly gastrointestinal stromal tumors and gastric adenocarcinoma.

The presence of perigastric lymphadenopathy and apparent peritoneal carcinomatosis initially suggested advanced epithelial malignancy. However, lymphomatous dissemination may produce similar radiologic patterns, underscoring the need for histologic confirmation before therapeutic decisions. EUS-guided fine-needle biopsy allows acquisition of core tissue suitable for histology, immunohistochemistry, and molecular studies, which are essential for classification of lymphoid neoplasms.

Aggressive mature B-cell lymphomas involving the stomach are typically diagnosed in older adults and often present with advanced-stage disease and extranodal involvement. Molecular alterations involving MYC, BCL2, or BCL6 are associated with increased proliferation, resistance to apoptosis, and poorer prognosis. These cases may respond less favorably to standard immunochemotherapy, sometimes requiring intensified regimens.

Despite the aggressive biological behavior, early recognition and appropriate systemic therapy may achieve favorable metabolic responses. This case emphasizes three key points: lymphoma should remain in the differential diagnosis of atypical gastric masses; imaging suggestive of carcinomatosis does not exclude lymphoproliferative disease; and EUS-guided biopsy is crucial for accurate diagnosis and optimal management.

Figure 1. Upper endoscopy showing a subepithelial antral lesion with central erosion.

Figure 2. Endoscopic ultrasound demonstrating heterogeneous gastric wall lesions.

Figure 3. PET/CT imaging showing metabolically active disease with nodal and peritoneal involvement (upper images) and CT scan revealing gastric wall thickening with mass effect near the pancreas (lower images)

References

1. Polkowski M, Jenssen C, Kaye P, et al. Endoscopic ultrasound-guided tissue acquisition: ESGE guideline. Endoscopy. 2017;49:989-1006.
2. Pimentel-Nunes P, Libânio D, Bastiaansen BAJ, et al. Endoscopic subepithelial lesions: ESGE Guideline. Endoscopy. 2022;54:412-429.
3. Swerdlow SH, Campo E, Pileri SA, et al. WHO classification of lymphoid neoplasms. Blood. 2016;127:2375-2390.
4. Kimbrough CW, Kim MP. Gastric lymphoma: current perspectives. J Surg Oncol. 2020;122:1131-1138.
5. Olszewski AJ, Winer ES, Castillo JJ. Rituximab-based therapy in aggressive B-cell lymphomas. Leuk Lymphoma. 2014;55:1247-1257.
6. Cheson BD, Fisher RI, Barrington SF, et al. Lugano classification for lymphoma staging. J Clin Oncol. 2014;32:3059-3068.

Authors

Diogo Feijó¹, Carlos Borges Chaves¹, Margarida Ferreira¹, Nuno Almeida¹², Pedro Figueiredo¹²
¹Gastroenterology Department, Coimbra Local Health Unit, Coimbra, Portugal
² Faculty of Medicine, University of Coimbra, Coimbra, Portugal