Results: Macroscopically, the resected specimen consisted of solid mass that was connected to the patient's duodenal wall but not to the parenchyma of the pancreas. Microscopic examination of the tumor showed spindle shaped and epithelioid cells with mild nuclear pleiomorphism. Immunohistochemistry revealed that the cells are strongly positive with CD117, with focal expression of CD34 and SMA. Conclusion: GISTs are low-grade malignant mesenchymal tumors of the GI tract and are believed to originate from the neoplastic transformation of the Cajal cells, which are located between the longitudinal and circular layers of the muscularis propria. They most frequently arise from the second part of the duodenum where they push or infiltrate into the pancreas. In our case report, the patient's tumor exhibited extramural growth and mimicked a pancreatic tumor. Mantle cell lymphoma (MCL) is relatively a rare subgroup of non-Hodgkin lymphoma. We have experienced an uncommon case of MCL. A 65-year-old man was admitted to emergency service for upper gastrointestinal bleeding as melena. Gastric corpus wall thickness found increased and splenomegaly determined at whole abdominal ultrasonography. Endoscopic examination revealed subsequently, 1 cm diameter polypoid lesion at corpus anterior wall and 2 cm dimensioned elevated and vascularised lesion at corpus posterior wall. Endoscopic biopsy had reported as active gastritis and mucosal reactive hyperplastic changes with ulcerative background. After than total gastrectomy and splenectomy specimens examined diffuse infiltration of monotonous medium-sized, atypical lymphoid cells with hyperchromatic nuclei. These cells were positive for CD20, CD5, CD43, bcl-2 and CD79a, but negative for CD10, CD23 and bcl-6. Atypical lymphoid cells were present even in splenic hilus and lesser curvature lymph nodes. We reported this case as Primary Gastric Mantle Cell Lyphoma according to morphologic and immunohistochemical staining features. We report a 74-year-old man who had been searched for bicytopenia (anemia and thrombocytopenia). Bone marrow examination revealed extensive bone marrow metastasis of signet ring cell carcinoma. PAS, d-PAS and mucin histochemical markers performed to bone marrow sample which were all positive. Immunohistochemical markers were positive with MUC-1, MUC-5 AC, MUC-2 (focal staining), CK7, CK20, EMA, CEA and negative with vimentin, CD10, chromogranin. According to morphologic and immunohistochemical results we thought primarily gastrointestinal system malignancy, particularly stomach carcinoma. Upper gastrointestinal endoscopy performed subsequently, hemorrhagic ulcerative lesion had seen and taken biopsies. Endoscopic biopsy results showed metastatic signet ring cells origin from stomach. We report this case because bone marrow metastasis can be found commonly in some malignant tumors but diagnosing a nonhematologic malignancy from bone marrow is an unusual event. 