Solid pseudopapillary tumor of the pancreas

Clinical History

A 32-year-old, female Caucasian patient, presented to the emergency department of our hospital complaining of a post-prandial epigastric pain during the last 4 months. She had no history of ulcer or any other pathology of the upper gastrointestinal (GI) tract. Physical examination and laboratory tests were unremarkable.

Imaging Findings

Endoscopy of the upper GI tract revealed no pathologic findings. The patient underwent ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) of the upper abdomen.
Fig. 1: On US a lesion measuring 3cm in diameter was demonstrated in the pancreatic body. The lesion presented mixed hypo-and hyperechoic features. Cystic areas as well as calcifications were evident. Fig. 2-4: On contrast-enhanced CT the mass was well circumscribed with solid and cystic components. Mild enhancement was present in the solid parts. The pancreatic duct was slightly dilated in the tail region. The peripancreatic vessels appeared normal (Fig. 2: Unenhanced CT image, Fig. 3: Contrast enhanced CT image, Fig. 4: Curved reconstrunction). Fig. 5-7 MRI demonstrated a well-defined lesion with heterogeneous signal intensity on T1-and T2-w images. A cystic area was evident on T2-w images in the anterior aspect. After contrast administration the lesion enhanced partially and gradually but remained hypointense in relation to the normal pancreatic parenchyma (Fig. 5: T2 WI, Fig. 6: T1 WI, Fig. 7: Contrast enhanced T1 WI).
Differential diagnoses include serous cystadenoma, mucinous cystic tumor, solid-pseudopapillary tumor, islet cell tumor and complicated pseudocyst.

Discussion

Endoscopic US-guided FNA revealed characteristics of a low malignancy pancreatic tumor. The patient underwent a left pancreatectomy with preservation of the spleen. Histologic and immunohistochemical findings were consistent with the presence of a solid-pseudopapillary tumor (SPT) of the pancreas (Fig. 8, 9).
Fig. 8: Solid pseudopapillary tumor of the pancreas on the right side of the figure in association with the normal pancreatic parenchyma (H+E x 10). Fig. 9: The papillary pattern of growth and small cysts in the tumor are shown (H+E x 400).
SPT of the pancreas is rare and was first described by Franz in 1959. The tumor is indolent, associated with long patient survival, even in the presence of extension into adjacent organs or metastases. It occurs most frequently in young non-Caucasian women and it is slightly more common in the pancreatic tail.
On gross examination a solid, cystic, solid-cystic and/or hemorrhagic appearance may be possible. The tumor histology is generally characterized by solid areas with a pseudopapillary pattern and cystic spaces due to degenerative changes. The differential diagnosis includes acinar tumors, pancreatoblastoma and endocrine tumors.
On imaging the combined solid and cystic nature is usually evident. Sometimes the mass appears totally solid or has internal septa and calcifications. Areas of high signal intensity on T1-w images and low or inhomogeneous signal intensity on T2-w images may help to identify blood products. Moreover, SPT do not demonstrate the hypervascularity typically seen in islet cell tumors.
Although the radiologic features are often informative, significant overlap exists. Fine-needle aspiration or biopsy and cytologic or histologic analysis is needed for a definitive diagnosis in certain cases.

Differential Diagnosis List

Final Diagnosis

Solid pseudopapillary tumor of the pancreas

URL:	https://www.eurorad.org/case/7469
DOI:	10.1594/EURORAD/CASE.7469
ISSN:	1563-4086