Gastrointestinal Endoscopy
Volume 57 • Number 7 • June 2003
Copyright © 2003 American Society for Gastrointestinal Endoscopy
Diagnosis of solid-pseudopapillary neoplasm of the pancreas by EUS-guided FNA
Sonali S. Master MD
Thomas J. Savides MD
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Current affiliations: Division of Gastroenterology, University of California, San Diego, California.
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Reprint requests: Thomas J. Savides, MD, UCSD Division of Gastroenterology, 200 W. Arbor Dr., San Diego, CA 92103-8413.
Copyright © 2003 by the American Society for Gastrointestinal Endoscopy
Solid-pseudopapillary tumors (SPT) of the pancreas account for approximately 1% of all pancreatic neoplasms. They occur predominantly in young women, often do not cause symptoms, have low malignant potential, and are most commonly located in the body or tail of the pancreas. They generally are treated by surgical resection. Two cases of SPT of the pancreas diagnosed by EUS-FNA are described.
Case reports
Case 1
A 51-year-old woman presented with a 1-year history of abdominal pain, maximal in the epigastrium, associated with nausea and 2 episodes of vomiting. The symptoms were thought to be most consistent with functional dyspepsia. She noted no association of the symptoms with ingestion of food, and there had been no weight loss. There was no personal or family history of pancreatic disease. Examination and laboratory studies, including serum lipase, were unremarkable. Transabdominal US revealed a 1.8 × 1.6 × 1.2-cm hypoechoic mass in the body of the pancreas. CT confirmed the presence of an ill-defined, nonenhancing 1.5-cm soft tissue mass in the body of the pancreas, with decreased attenuation compared with the adjacent pancreatic tissue.
EUS with a radial echoendoscope revealed a 16 × 11-mm hypoechoic mass in the superior portion of the pancreatic genu. The mass was located within the pancreas and did not involve the pancreatic duct or any adjacent structure. At the request of the referring physicians, EUS-FNA was performed to document malignancy before subjecting the patient to a major pancreatic resection. The procedure was performed with a linear array echoendoscope (GF-UC30P, Olympus America Corp., Melville, N.Y.). A total of 2 passes were made with a 22-gauge fine needle (Wilson-Cook Medical Inc., Winston-Salem, N.C.). Evaluation of the cytologic specimens revealed a monomorphic population of small cells with scant to moderate cytoplasm and irregular nuclear membranes. Papillary fronds with fibrovascular stalks, trabecular areas, and microacinar structures were noted, as well as metachromatic hyaline globules. Immunohistochemical stains for chromogranin and synaptophysin were negative. These findings were consistent with a diagnosis of solid-pseudopapillary neoplasm.
The patient underwent a central pancreatectomy with Roux-en-Y pancreaticojejunostomy. Gross examination revealed a well-circumscribed, gelatinous-appearing, heterogeneous mass measuring 1.8 × 1.4 × 1.3 cm. Histopathologic evaluation demonstrated pseudopapillary areas, fibrosis, hyalinization, slit-like cystic spaces, and hemorrhage. There were no mitoses or nuclear pleomorphism. No perineural invasion or vascular invasion was identified. The surgical resection margins were free of tumor. The histopathologic findings confirmed the previous FNA-cytologic diagnosis of solid-pseudopapillary neoplasm of the pancreas.
Postoperative recovery was uneventful. At an 18-month follow-up, the patient continued to experience similar abdominal symptoms thought to be caused by nonulcer dyspepsia. There was no evidence of endocrine or exocrine pancreatic insufficiency and no evidence of tumor recurrence or metastatic disease.
Case 2
A 32-year-old woman with no GI symptoms or history of pancreatic disorder underwent magnetic resonance imaging to further evaluate an enlarged right ovary. This revealed a large, complex, cystic mass posterior to the gastric body. CT revealed a 4.6 × 4.1-cm well-circumscribed mass with a cystic portion originating within the junction of the body and neck of the pancreas (Fig. 1A).
Fig. 1. A, CT showing 4.6 × 4.1-cm well-circumscribed pancreatic mass with cystic component. B, Radial EUS image (7.5 MHz, range 12 cm) showing 34 × 37-mm cystic pancreatic lesion with debris/solid component.
EUS was performed with a radial echoendoscope with imaging at both 7.5 and 12 MHz. This revealed a 45 × 35-mm mixed cystic and solid lesion at the pancreatic genu (Fig. 1B). On imaging, it was unclear whether this lesion represented a benign pseudocyst with debris versus a solid mass with a cystic component. Transgastric FNA was performed with removal of all of the fluid from the cystic portion of the lesion. FNA was then performed of the solid/debris portion of the lesion, a total of 5 passes being made with a 22-gauge fine needle (Wilson-Cook).
Fluid analysis of the cystic portion revealed an amylase of 51 U/L, lipase of 32 U/L, CA 19-9 of 5 U/mL (0-37 U/mL), and CEA of less than 0.2 ng/mL (0-3.0 ng/mL). Examination of the cellular aspirate from the mass lesion revealed loosely cohesive aggregates and single monomorphic cells with moderately enlarged nuclei and a moderately increased nuclear/cytoplasmic ratio, as well as characteristic papillary structures (Fig. 2A).
Fig. 2. A, Photomicrograph of EUS-FNA specimen showing characteristic papillary structures (Papanicolau stain, orig. mag. ×100). B, Photomicrograph of tissue section demonstrating solid and papillary areas (H&E, orig. mag. ×100).
The chromatin was fine and evenly distributed. Immunostains showed a strong positive reaction with neuron specific enolase and a weak reaction with chromogranin in only rare cells. The tumor cells were also positive for vimentin (diffuse strong reaction) and alpha-1-antitrypsin. Synaptophysin and cytokeratin were negative. These findings were consistent with a diagnosis of solid-pseudopapillary neoplasm of the pancreas. The patient subsequently underwent a segmental resection of this lesion. Histopathologic evaluation demonstrated both solid and pseudopapillary areas (Fig. 2B). Immunocytochemical stains confirmed the findings for the aspirate, and, in addition, the tumor cells exhibited a positive reaction for progesterone receptor and a negative reaction for estrogen receptor.
At a 6-month follow-up, the patient was asymptomatic from a GI standpoint, with no signs of tumor recurrence, metastases, or signs of either endocrine or exocrine insufficiency of the pancreas.
Discussion
SPT of the pancreas was first described in 1959.[1] There have since been many synonyms for SPT used in various publications; some of these are solid and papillary epithelial neoplasm, solid and cystic tumor, papillary-cystic neoplasm, papillary cystic tumor, and Franz's tumor. In 1996, this tumor was renamed solid-pseudopapillary tumor by the World Health Organization for the histologic classification of tumors of the exocrine pancreas.[2]
Although these tumors have characteristic cytologic and histologic features, their cell of origin remains unclear. During embryogenesis, the genital ridges are in close proximity to the pancreatic anlage. Some have speculated that SPTs may come from genital ridge/ovarian anlage-related cells, which were attached to the pancreatic tissue during early embryogenesis.[3] Yet others have considered ductal, acinar, and endocrine cell origins without convincing evidence.
SPTs comprise approximately 1% of all pancreatic neoplasms, and in one center they accounted for 12% of 134 resected, clinically cystic pancreatic tumors.[4] These tumors most commonly are identified in young women. In one series of 59 SPTs, 88% of the patients were women.[3] Mean age at diagnosis is approximately 26 years, with a reported range of patient's age from 8 to 70 years.[3] [5] [7] Patients with SPTs are frequently asymptomatic, and the tumor is often found incidentally on imaging studies performed for other indications. When present, symptoms are nonspecific and may include nausea, vomiting, abdominal pain, and fullness. These lesions can present at any size, with reported dimensions ranging from 1.5 to 30 cm (mean 10.5 cm).[8] They most commonly are located in the pancreatic body and tail. On CT, SPTs may appear as well-circumscribed hypodense lesions with or without obvious cystic change.[9]
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