Over the past several years, mucin-producing pancreatic tumors have become a much more widely recognized entity. With increasing awareness has also come an evolution of concepts and nomenclatures regarding this set of pancreatic neoplasms. Understandably, this maturation process has led to confusion over categorization, management, and prognosis. This article will propose a unifying view of these mucin-producing tumors and provide imaging examples for illustrations.
Mucin-producing pancreatic tumors should be considered when cystic lesions of the pancreas are found. Most pancreatic "cysts" are nonneoplastic, usually inflammatory pseudocysts. Approximately 5-15% of these cystic masses will be neoplastic [1]. Until 1978, the term "cystadenoma" was used to describe cystic neoplasms of the pancreas [2,3]. At that time, the mucinous tumors were subdivided from the serous cystadenoma. More recently, the mucinous tumors have been furthur subclassified into two major groups: intraductal papillary mucinous neoplasm and mucinous cystic neoplasm.
These two entities share a common array of epithelia that ranges from adenomatous, to proliferative ductal epithelium, to invasive carcinoma. These different epithelia may be present within a single tumor or may evolve toward the more aggressive form, similar to that of colon carcinoma [4]. Most consider both mucinous lesions as at least premalignant if not a low-grade malignancy [5]. In general, both lesions are associated with a better prognosis than the more common ductal carcinoma. However, the intraductal papillary mucinous neoplasm and mucinous cystic neoplasm differ sufficiently in clinical presentation, anatomic location, radiographic appearance, and patient demographics (Table 1) to justify their division.