Solitary gastric plasmacitomas are infrequent tumors. They account for 5% of the extramedullary plasmacitomas. We report an unusual case in a 14 years old boy. The patient has had gastric symptoms for 2 years prior to an endoscopic examination. A fungating, ulcerated lesion was observed in the antrum. The biopsies showed a monoclonal, Lambda positive, diffuse, plasmocitic proliferation infiltrating the mucosa. Also a moderate number of Helicobacter pylori were identified in the gastric pits and numerous lymphoid follicules were observed in the deep portion of the mucosa. In view of the presence of HP infection the patient was treated with Orneprazole and Clarithromycin. Endoscopic examination and biopsies performed 3 and 5 months later showed a complete remission of the gastric lesion. At the time of this report the patient is in good physical condition, has recovered his weight and has grown 5 cm. Differential diagnosis with plasmo limpho in chronic gastritis and with lympheicitic lymphoma with plasmocitoid features had to be done. The macroscopic appearance of the gastric lesion, the absence of other inflammatory cells and monoclonality of the plasmocitic infiltration ruled out chronic gastritis. The negative staining for CD 20 as well as the abscence of lymphoid cells in the mucosal infiltrate give support: to the diagnosis of plasmocitoma. The close association between gastric MALT lymphoma and HP infection has been reported as well as its regression after antibiotic treatment for its erradication. In our review of the literature we failed to find any references to the association of HP with gastric plasmocitoma nor to its regression after antibiotic therapy.