A rare case of abdominal plasmacytoma is described. A computed guided biopsy of abdominal mass permitted an accurate diagnosis. Blood findings revealed an increased gamma-globulin level and serum immunoelectrophoresis revealed high IgG-kappa spike. Bone marrow biopsy resulted negative for neoplastic infiltration. Plasmacytoma is a malignant proliferation of differentiated B lymphocytes which produce immunoglobulin. In our case, microscopically, biopsy of abdominal mass revealed the presence of plasmablasts with bizarre multiforme nuclei, spindled contours and positive immunoenzymatic reaction for CD38, suggestive for plasma cell proliferation.