Gastric tumors share many characteristics, making a definitive diagnosis challenging. Gastric adenocarcinomas represent 90% of malignant stomach tumors, meanwhile the frequency of gastric lymphoma range between 1-5% of all gastric cancers. Gastric carcinoma bears resemblance with particular forms of non-Hodgkin's lymphoma of the stomach, not only in morphological presentation, but also in clinical configuration and laboratory tests. We report a case of gastric carcinoma with abnormal hematological picture dominated by leukemoid reaction and peculiar histopathological aspect. Pleomorphism of neoplastic cells and distinct arrangement of these give rise to the need of differentiation between a carcinoma and a non-Hodgkin's lymphoma of the stomach. On immnohistochemical grounds, we succeeded in our action of segregation between the two lesional entities and we establish as definitive diagnosis that of poorly differentiated gastric adenocarcinoma. Additionally, leukemoid reaction proved to be a manifestation of a bone marrow metastasis from gastric cancer.