IPMN Natural History: A Story Very Much Still Evolving

Abstract

Purpose: First described in 1982, intraductal papillary mucinous neoplasm (IPMN) has been recognized with increasing frequency in patients with and without symptoms referable to the pancreas. The literature on IPMN has been fast accumulating, including an international consensus guidelines publication in 2006. However, much remains to be learned about the natural history of this entity as evidenced by the case report below: In 2000, a 79-year-old white nonsmoker, tea-totaler asymptomatic woman sought medical attention because of the new diagnosis of ovarian cancer in her older sister. Her CA 19-9 was 200 (nl <37), leading to a CT showing small pancreatic cysts. For the ensuing 3 years, CA 19-9 fluctuated between 116 and 444. Because of the CA 19-9, patient was seen at our institution in 2003 when her CA 19-9 was 129. Since then, multiple MRCP, CT pancreas protocol, EUS examinations, and one ERCP were performed at annual interval. In 2008, a secretin MRCP was compared to her first MRCP in 2003, demonstrating no change. Seen were multiple sub-centimeter cysts throughout the pancreas, some of which were connected to a nondilated pancreatic duct, consistent with side branch IPMN. Because of the stability of these lesions and the patient's age, these lesions were reported by Radiology as being of doubtful clinical significance. However, a repeat MRCP 13 months later showed a new 2 cm mass at the head of the pancreas. EUS-guided biopsy showed adenocarcinoma. The patient described herein lacked all of the features commonly thought of as high-risk predictors for progression to high grade dysplasia or malignancy. Specifically, she had side branch IPMN, with pancreatic duct diameter <10 mm, cysts <10 mm, and no internal cystic nodules. Yet, her pancreas underwent a malignant transformation, contrary to published reports of majority (84%) having no change within a 5-year follow-up and no carcinoma. The possibility therefore exists that the so-called low risk group of patients with side-branch IPMN are quite heterogeneous, with some capable of developing adenocarcinoma. Until the risk factor profile for this subgroup is defined, clinical management of patients with IPMN will require individualized flexibility and IPMN natural history is still very much an evolving story.