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I read with great interest the recent paper by Sanada and Yoshida on benign intraductal papillary mucinous neoplasm (IPMN) of the pancreas containing two major subtypes [1]. In this case report the authors describe the coexistence of a gastric type IPMN with an intestinal type. The former was composed of benign pyloric-type mucosa (hence, IPM adenoma) and was located mainly in the branch pancreatic ducts. This lesion then transitioned into the main pancreatic duct that also harbored an intestinal type IPMN of borderline cytological atypia. In addition, the small ducts contained lesions of PanIN 1A and 1B which communicated with the gastric type IPMN. The morphologic features were supplemented by MUC staining which clearly delineated gastric and intestinal type mucosae constituting the entire lesion [1]. These are indeed interesting observations and Sanada and Yoshida are to be complimented for their meticulous sampling of the lesion and documentation of the histopathologic fi ndings. However, they state combinations of the different histologic types of IPMN within the one lesion are uncommon. In the paper by Adsay et al, they delineated a category, which they deemed “unclassifi able” [2]. This category was reserved for cases that could not specifi cally be placed into one of the 3 major types or comprised areas of intestinal or pancreaticobiliary epithelium, neither of which was considered the dominant histologic type. Most importantly, this paper goes on to say, “many of the intestinal and pancreatobiliary types had null (gastric type) type components” [2]. In the Discussion section of this paper, the authors conclude that the null or gastric type “is often present in the background of the other two types” [2]. Furthermore, in the consensus paper of 2005, it is also stated, that “areas with gastric-type epithelium can be associated with the other subtypes, implying that the gastric type might be a common precursor of the other types” [3]. In a review of our own material of over 50 IPMNs, gastric type IPMN coexisting with the other types was frequent (seen in approximately 30-35% of cases), and in fact, coexistence of intestinal and pancreatobiliary, intestinal and oncocytic and pancreatobiliary with oncocytic subtypes were also encountered. The nomenclature used to designate an IPMN is based on the dominant histologic pattern seen. In the case described by Samada and Yoshida it would seem perfectly acceptable to consider the IPMN to consist of two types of epithelium because neither type appeared to predominate, although this is not stated explicitly in the description. However, the crux of the issue is that the different types of epithelium that constitute IPMNs frequently coexist, although one type tends to predominate and the IPMN should be labeled after the predominant epithelial type. Also of major interest and great speculation is the association between gastric type IPMN and PanIN. Not only do they share locations (localized to branch and small ducts), they are lined by similar if not identical pyloric-type epithelium and share the same MUC expression profi le. The arbitrary cut off fi gure of ducts 1cm or more harboring IPMN and ducts smaller than 1cm housing PanIN, is purely for the convenience of separating the two lesions. It does not take into account a possible temporal sequence of events where IPMNs at sometime may have been less than 1cm in size, despite being lined by similar epithelium as PanIN. Several have commented on the extreme diffi culty separating the two lesions and perhaps there is a continuum between PanIN and gastric type IPMN.