Rare Pancreatic Neoplasm: Solid Pseudopapillary Epithelial Tumor (SPEN) – Imaging features. YENEPOYA UNIVERSITY Dr. Ayshath Shamseena 2nd Yr Post Graduate Dept. Of Radio Diagnosis Yenepoya Medical College Mangalore, Karnataka.

Aim To describe the imaging features of solid pseudopapillary epithelial neoplasm of pancreas on ultrasound and contrast enhanced computed tomography.

Materials and Methods Two female patients aged 16 and 25 year who presented with vague abdominal pain were included in the study. Ultrasound was done with GE Voluson E8. Plain and contrast enhanced computed tomography was done using GE 16 slice multidetector computed tomography for further evaluation. Computed tomography guided fine needle aspiration cytology was done for histopathological confirmation.

Ultrasound Images a b Images a and b show a well defined solid cystic predominantly hypoechoic lesion in relation to the pancreas.

Computed Tomography Images b Axial computed tomography images depict a well defined hypodense lesion in relation to the head and body of pancreas with focal calcification in (a) plain and (b) in arterial phase.

a b Computed tomography images in venous phase showing a heterogeneously enhancing well defined lesion in the head and body region of pancreas – (a) axial and (b) coronal reformatted images.

a b Axial computed tomography images depict a well defined hypodense lesion in relation to the tail of pancreas in (a) plain and (b) in arterial phase.

a b Computed tomography images in venous phase showing a heterogeneously enhancing well defined lesion in the tail of the pancreas – (a) axial and (b) coronal reformatted images.

a b Axial plain computed tomography images during fine needle aspiration cytology procedure.

Results In both cases, ultrasound demonstrated a well defined solid cystic predominantly hypoechoic lesion in relation to the pancreas with no significant vascularity. Contrast enhanced computed tomography revealed heterogeneously enhancing well defined mixed density lesion in the pancreas. Computed tomography guided fine needle aspiration cytology confirmed the diagnosis of solid pseudopapillary epithelial neoplasm of pancreas in both cases.

Discussion Solid pseudopapillary epithelial neoplasms (SPEN) of the pancreas are rare exocrine pancreatic tumors.(1) It was first described by Franz in 1959 as a “papillary tumor of the pancreas, benign or malignant.”(1) Epidemiology – Rare – 1-2% Predominantly affects non-Caucasian individuals with predilection for Asians and Afro Americans. Age – Young with peak in the 2nd and 3rd decade. Sex – Female (male:female ratio – 1:10)(2)

Clinical Presentation – Usually asymptomatic. Occasionally may present with mass per abdomen or vague abdominal pain.(3) Pathology - Gross – large, well encapsulated with varying amount of necrosis, hemorrhage and cystic change. Microscopy – two distinct types – solid and papillary. Solid – necrosis, foamy macrophages, cholesterol granulomas and calcifications may be seen. Papillary – composed of fibrovascular stalk surrounded by several layers of epithelial cells.(1)

Imaging – Ultrasound – well defined mass consisting of solid as well as cystic components. Multi detector Computed Tomography (MDCT) – Large solid-cystic masses in the pancreas with peripheral capsule formation. Enhancing solid components and septae. Calcification may be present in the mass.(1,5) Fine-needle aspiration biopsy and cytologic analysis or excisional biopsy and histologic analysis are needed for definitive diagnosis. (6)

Treatment and Prognosis The treatment of choice is surgery with complete resection. In most patients, prognosis is excellent. However, malignant transformation has been reported. Metastasis may occur to the liver and peritoneum in some rare cases.(7)

Conclusion Solid pseudopapillary tumors of the pancreas are a rare but treatable pancreatic tumor most frequently seen in young women. Typical appearance consists of an encapsulated mass with varying cystic and solid components caused by hemorrhagic degeneration; calcification and heterogeneous enhancement of intralesional components. Ultrasound and Multidetector computed tomography are useful in the identification of such lesions and thus for a formation of a good differential diagnosis.

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