Introduction: The gastrointestinal tract is the most common extranodal site for non-Hodgkin's lymphoma, with the most common being diffuse large B cell lymphoma. Unlike the stomach or the ileum, the jejunum is a rare site for primary extranodal lymphomas, given the scarcity of lymphoid tissue. Due to its location, inflammation in the jejunum may not be visualized on routine imaging or endoscopy, making jejunal lymphoma difficult to diagnose. Case Description: We present a case of a 90-year-old male with 1 week of intractable emesis, initially thought to be due to viral gastroenteritis. His symptoms never improved and he underwent serial CT imagings in addition to esophagogastroduodenoscopy. A stomach biopsy and a diagnostic paracentesis did not reveal any malignant cells, but a CT enterography revealed significant jejunal inflammation with obstruction. After a month of hospitalization, a jejunal biopsy was obtained, which showed proliferation of neoplastic B cells. He was ultimately diagnosed with primary jejunal diffuse large B cell lymphoma. Discussion: Chemotherapy and surgical resection are typically the definitive treatment for extranodal lymphoma. Clinicians, however, must carefully consider the patient's functional and nutritional statuses before offering such interventions. This case was a diagnostic challenge and demonstrated a rare GI malignancy's convoluted mimicking nature.