ABSTRACT Benign polyps of the stomach undergo malignant transformation at a rate correlating to the histological type and size of the proliferative lesion. We report a case of a 50-year-old Caucasian woman, affected by a diffuse gastric polyposis of both hyperplastic and adenomatous type. At endoscopy polyps were more than 1,000, scattered over the entire gastric cavity. The patient underwent total gastrectomy. The perilesional gastric mucosa was characterized by the presence of either atrophic or metaplastic areas and by a mild dysplasia. A single tubu- lo-villous adenomatous polyp was also present in the ascending tract of the colon. The absence of both high-grade dysplastic lesions and outbreaks of neoplastic transformation well correlated with the histo- chemical and molecular features, confirming the highly proliferative pattern of the polyps in the lack of signs of malignant progression. Key words: Diffuse gastric polyposis. Hyperplastic polyps. Ade- nomatous polyps. Malignant potential. Immunohistochemistry. Mol- ecular assay. INTRODUCTION Benign polyps of the stomach present as a heterogeneous group of lesions. The two most common types are the hyperplastic and the adenomatous polyps, which have dis- tinct features and different rates of progression toward malignancy (1). The rate of malignant transformation is related to the histological type and size of the polyp and it is estimated to be 18% for adenomatous polyps compared to the rate of 1.5-4.5% for hyperplastic polyps, according to recent studies (2,3). Metaplastic changes occur in 16.7% of hyperplastic polyps and in 72.7% of adenomatous polyps, mostly within the perilesional mucosa, which is constantly infiltrated with polymorphonuclear elements (2). Polyps with mixed characteristics, i.e. showing both adenomatous and hyperplastic areas have been also described (4). Patients with adenomatous-hyperplastic polyps feature high levels of gastrin and only occasionally showed to carry Helicobac- ter pylori infection (5,6). Gastrin is believed to favor neo- plastic growth (5,6). In diffuse gastric polyposis, a less com- mon disorder, the gastric mucosa is largely filled with polyps (at least more than 50) and patients are usually affected by severe anemia (5,7). Among the various pathogenetic hypotheses explaining the histomorphologic progression of gastric lesions, the one proposed by Correa (with the sequence: gastritis-intesti- nal metaplasia-dysplasia-gastric carcinoma) is greatly favored, whereas the direct sequence from adenoma to car- cinoma, though generally accepted for colon cancer, is ques- tioned (8-10). We report a rare case of diffuse gastric polyposis of both hyperplastic and adenomatous type. Histological and mol- ecular findings of the lesions are discussed with respect to their proliferative pattern and malignant potential. Evaluation of the oncogenic risk of diffuse gastric polyposis. A case report Erasmo Spaziani 1 , Marcello Picchio 2 , Annalisa Di Filippo 1 , Piero Narilli 3 , Luca Pacini 4 , Valentina Moretti 4 , Pierino Lucarelli 5 , Francesco De Angelis 1 , Giuseppe Ragona 4 and Vincenzo Petrozza 4 1 Department of Medico-Surgical Sciences and Biotechnologies. University of Rome Sapienza. Hospital “A. Fiorini”. Terracina, Latina, Italy. 2 Department of Surgery. Hospital “P. Colombo”. Velletri, Rome, Italy. 3 Department of Surgery. General Hospital “Nuova Itor”. Rome, Italy. 4 Department of Medico-Surgical Sciences and Biotechnologies, University of Rome, Sapienza, Latina, Italy. 5 Department of Surgery. Hospital “Madonna delle Grazie”. Velletri, Rome, Italy 1130-0108/2012/104/9/493-496 REVISTA ESPAÑOLA DE ENFERMEDADES DIGESTIVAS Copyright © 2012 ARÁN EDICIONES, S. L. REV ESP ENFERM DIG (Madrid) Vol. 104. N.° 9, pp. 493-496, 2012 Received: 24-02-2012 Accepted: 25-06-2012 Correspondence: Annalisa Romina Di Filippo email: annalisa.difilippo@alice.it CLINICAL NOTE Spaziani E, Picchio M, Di Filippo A, Narilli P, Pacini L, Moretti V, Lucarelli P, De Angelis F, Ragona G, Petrozza V. Evaluation of the oncogenic risk of diffuse gastric polyposis. A case report. Rev Esp Enferm Dig 2012;104:493-496. Copyright notice: With kind permission from Springer Science + Business Media: Spaziani E, Picchio M, Di Filippo A, Narilli P, Di Cristofano C, Petroz- za V, De Angelis F, Ragona G. Sporadic diffuse gastric polyposis: report of a case. Surgery Today 2011; 41(10):1428-31.