Although Cyst of the pancreas is distinctly not a rarity, it cannot be classed among the common abdominal tumors. In a classical, comprehensive review of this subject in 1898, Korte (1) collected 121 cases from the medical literature. Judd et al. (2), in a more recent survey of the subject, state that out of more than 700,000 admissions to the Mayo Clinic between 1921 and 1931, only 88 patients were treated surgically for pancreatic cyst. Rabinovitch and Pines (3) reported 17 cases, in 14 of which operation was done. Virtually all other published articles regarding this entity have dealt with but one or a few patients. The relatively infrequent occurrence of pancreatic cyst is further emphasized by a review of the case records of the University Hospital (Ann Arbor), which reveals that, since July 1935, only 13 patients have received surgical treatment for. this entity. Because of this relatively low incidence of pancreatic cyst and the difficulties commonly encountered in its diagnosis, a brief analysis of pertinent findings which may facilitate that diagnosis seems warranted. Emphasis will be placed upon a particular combination of clinical and roentgenological signs occurring in conjunction with cysts arising in the tail of the pancreas. These signs have not been utilized to their fullest extent in the past, although frequently they are of great diagnostic value. Classification The classification of pancreatic cysts is at considerable variance. Suffice it to say that the majority of true cysts are either of the retention or the proliferative type. The former type is more common and is usually due to dilatation of a pancreatic duct. Korte (1) proposed the term pseudocyst for that type found in more or less close proximity to the pancreas, but apparently not arising in the gland substance, and existing without an epithelial lining. Apparently this type of lesion occurs more frequently than any of the true cysts; it usually arises near the tail of the pancreas. Clinical Findings The symptoms of pancreatic cyst are not at all distinctive and may be closely simulated by numerous other intra-abdominal lesions. Certainly the most constant and important subjective complaint is pain, but it is so variable in location and extent that it has but little diagnostic value. Loss of weight, weakness, nausea, vomiting, and diarrhea are common but even less consistent symptoms. Jaundice may occur when a cyst grows large enough to obstruct the biliary duct system. If the cyst is large enough to produce symptoms, a smoothly rounded mass usually may be palpated in the upper portion of the abdomen. This mass may appear suddenly, may slowly enlarge over an interval of months or years, or may fluctuate in both size and shape. The position and mobility of the mass are largely dependent upon the site of origin of the cyst, i.e., the portion of the pancreas from which the cyst arises.