LAUSR

A 42-year-old woman presented with a 3-month history of generalized abdominal pain. She had no history of pancreatitis. The examination of the abdomen was unremarkable. Tumour markers (Ca19-9 and CEA) were within normal range. Three-phase computed tomography (CT) of the abdomen revealed a circumscribed ovoid mass in the neck of the pancreas measuring 28 mm in maximal diameter, heterogeneously hypodense relative to pancreas on pre-contrast imaging and associated with small foci of cystic change (Fig. 1). There was mild heterogeneous enhancement, with the lesion predominantly hyperdense on venous phase. There was no proximal pancreatic duct dilatation. Based on the finding of a mixed density pancreatic neck mass, a radiological diagnosis of solid pseudopapillary tumour was given. Endoscopic ultrasound confirmed these findings and supported the diagnosis of solid pseudopapillary tumour. A central pancreatectomy was performed and concomitant vascular resection was not required. At 8 months of follow-up, the patient has no evidence of recurrence or abdominal pain and has returned to normal activities. Macroscopically, the tumour was a well-circumscribed tan lesion with focal cystic areas. Microscopically, the tumour demonstrated a pushing margin beneath a thin fibrous capsule. The tumour comprised disordered pancreatic ducts lined by cuboidal to low columnar epithelium embedded in an inflammatory fibroblast-rich stroma with admixed mature fat (Fig. 2). Some pancreatic acini were seen at the periphery of the tumour, but discrete endocrine islets were lacking. No cytological atypia was seen and there was no abnormality in the surrounding pancreatic parenchyma. The tumour was completely excised. Elastic staining (Verhoeff-Van Gieson) demonstrated a lack of concentric elastic fibres in the walls of the pancreatic duct, but preserved in the pancreas surrounding the tumour. S100 immunohistochemistry demonstrated a lack of peripheral nerves in the tumour but highlighted mature fat within the tumour. The fibrous stroma was diffusely positive for CD34, and chromogranin was negative (Fig. 3). Based on the lack of normal components of the pancreas (i.e. concentric elastic fibres in the duct walls, peripheral nerves and well-formed islets of Langerhans), chronic pancreatitis was ruled out as a diagnosis, and confirmed the diagnosis of a pancreatic hamartoma (PH). PH is a rare benign lesion most commonly in the head of the pancreas, but has also been described in the body and tail. The tumour affects patients of a broad age spectrum, ranging from neonates to the elderly, with no gender predilection. Due to the rising prevalence of cross-sectional abdominal imaging, an increasing number of PH are being diagnosed incidentally. However, larger lesions may present with abdominal pain, an abdominal mass and/or weight loss. Tumour marker levels (Ca19-9, CEA, Ca-125, Chromogranin A) remain unelevated in the presence of PH. Fig. 1. Axial computed tomography images demonstrating the pancreatic hamartoma in the neck of the pancreas (green arrow). Panel (a) demonstrates a hypodense lesion on non-contrast phase. Panel (b) demonstrates a heterogeneously enhancing lesion on arterial phase. Panel (c) demonstrates the peak of contrast enhancement in venous/delayed phase with focal cystic change.