INTRADUCTAL PAPILLARY MUCINOUS NEOPLASM OF THE PANCREAS: PRESENTATION IN A YOUNG ADULT RITA PASSANTINO - LORENZO MARASA’ Department of Pathology, A.R.N.A.S. Civico, Palermo

INTRODUCTION Intraductal Papillary Mucinous Neoplasms (IPMNs) are a distinct type of intraductal pancreatic tumours that have been defined and segregated from other neoplams of this organ (particularly Mucinous Cystic Neoplasms, MCNs) only recently. IPMNs are the most common intraductal tumours of the pancreas. Although they show an adenoma-carcinoma sequence, they have proved to have a more favorable prognosis than ductal adenocarcinoma, when resected in a preinvasive state.

INTRODUCTION IPMNs are mucin-producing epithelial tumours that usually show a papillary architecture and are associated with involvement and dilatation of several major pancreatic ducts. Clinically, these lesions often produce pancreatitis because of the hypersecretion of mucous. Recently, it has become clear that IPMNs constitute a heterogeneous group with at least four subtypes with different biological properties and different prognostic implications.

CASE REPORT In this report, one of the youngest cases of IPMNs is de-scribed. The patient was a 34-year-old man with several episodes of acute recurrent pancreatitis in the past 6 months, on February 2008 admitted for dyspepsia, nausea and loss of appetite. Computed tomography showed a cystic lesion in the head of pancreas which communicated and extensively involved the large pancreatic ducts. Endoscopic retrograde cholangiopancreatography demon-strated mucin oozing from ampulla of Vater. Cephalopancreaticoduodenectomy was performed.

HISTOLOGICAL EXAMINATION GROSS EXAMINATION The tumour massively involved either the main pancreatic duct or its branches. There was marked dilatation of a major pancreatic duct with fibrosis and atrophy of the surrounding parenchima. This duct contained large amounts of mucin in its lumen. HISTOLOGICAL EXAMINATION There was a multicentric involvement of major ducts by a predominantly papillary lesion with an “intestinal” differentation: a large mucin-producing papillary neoplasm, with a main focus of 1.8 cm in greatest diameter, made up columnar cells with cigar-shaped nuclei and mild dysplasia, in a context of an obstructive chronic pancreatitis. IMMUNOHISTOCHEMICAL EXAMINATION The tumour showed the characteristic immunohistoche-mical profile of “intestinal type” of IPMN with expression of MUC-2, MUC5AC, CDX2 and absent expression of MUC-1.

HISTOLOGICAL EXAMINATION Involvement of major duct by a predominantly papillary lesion with an “intestinal” differentation

HISTOLOGICAL EXAMINATION An intraductal mucin-producing papillary neoplasm, in association with a chronic pancreatitis

IMMUNOHISTOCHEMICAL EXAMINATION MUC-2 MUC5AC CDX-2 MUC-1

CONCLUSIONS IPMNs are now being reported more frequently with larger case series. The reason for the increasing recognition of the disease is unclear, but is at least partially the result of a rising awareness of the disease and an increasing use of cross-sectional imaging. The natural history of these lesions is to spread slowly over the ductal system with eventual progression in some cases to invasive carcinoma. In the “intestinal type” of IPMNs the invasive component is an invasive mucinous (colloid) adenocarcinoma with a better prognosis than ordinary ductal adenocarcinoma.

CONCLUSIONS The potential for this neoplasms to diffusely involve the pancreatic ducts has been recognized, making treatment decisions difficult. The crux of the issue is whether a partial pancreasectomy is adequate treatment and what effect the histologic status of the margin has on outcome. More extensive surgery may be needed in IPMNs, such as total pancreasectomy, especially in cases of diffuse ductal dilation of the pancreas. Anyway, because of a limited number of cases, prognostic factors and the natural history of IPMNs have not been well defined.

MAIN REFERENCES Andrejevic-Blant S et al. Pancreatic intraductal papillary-mucinous neoplasms: a new and evolving entity. Virchows Arch. 2007 Nov; 451(5): 863-869. D’Angelica M et al. Intraductal papillary mucinous neoplasms of the pancreas. An analysis of clinicopathologic features and outcome. Ann Surg. 2004 March; 239(3): 400-408.