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Histological examination of the pancreatic and liver lesions confirmed the diagnosis of solid pseudopapillary carcinoma. The resection margins of the pancreas and the liver were clear of tumor. The patient recovered well from the operation and there was no evidence of recurrence 6 months afterward. No adjuvant therapy was given.
Solid pseudopapillary tumor (SPT) of the pancreas was first described by Frantz1in 1959. Since then, only about 450 cases of SPT of the pancreas have been reported.2Various other names such as papillary cystic and solid tumor of pancreasand papillary cystic neoplasm of pancreashave been used to describe this rare tumor, and it was classified as solid pseudopapillary tumor of the pancreasby the World Health Organization in 1996.2
The most important clue to the diagnosis of SPT is a large pancreatic tumor occurring in a young female. The female-male ratio is 9:1. About 15% of SPTs are malignant. Most of them would have liver or peritoneal metastasis at presentation. Calcification is also a common feature of the tumor. Although ductal adenocarcinoma of the pancreas is the most common tumor of the pancreas, it seldom occurs in this much younger age group. Mucinous cystadenocarcinoma may be associated with increased levels of carcinoembryonic antigen and usually occurs in older patients. Cystic islet cell tumors seldom grow to such a large size and may be associated with a hormonal syndrome. Hydatid disease in this case is unlikely since the computed tomography features were not suggestive of it and the disease is of low prevalence in this locality.
Solid pseudopapillary tumor accounts for about 1% to 2% of all nonendocrine pancreatic tumors. A majority of the patients have vague abdominal pain or an upper abdominal mass. Most SPTs have an indolent course. Increased malignant potential is associated with advanced age, male sex, invasion into adjacent normal pancreatic parenchyma, cellular atypia, and vascular or perineural invasion.2Although computed tomography usually shows a well-circumscribed lesion with a solid or cystic component, none of these radiological features are diagnostic. The role of fine-needle aspiration cytology in establishing the diagnosis is limited since the histological features vary from area to area and, therefore, the false-negative rate is high.2
The gross appearance of solid pseudopapillary tumors depends on the degree of necrosis. They are usually well demarcated, and on cross section, they reveal hemorrhage and cystic degeneration admixed with more solid areas. Histologically, SPTs exhibit solid, cellular areas that lack gland formation or other specific architectural features. They are typically positive for vimentin, neuron-specific enolase, α1-antitrypsin, and α1-antichymotrypsin and are negative for chromogranin, epithelial membrane antigen, and cytokeratin.
The etiology of this tumor remains a mystery. It is believed that it comes from embryonic multipotential stem cells that can differentiate to ductal, acinar, or endocrine components. Because of the high female sex dominance in this tumor and the possible younger age of cancer development in females, a hormonal influence in the pathogenesis has been suggested for pancreatic SPTs. The role of estrogen receptors and progesterone receptors has been studied, but the results remain conflicting.3
Surgery is the mainstay of treatment for SPT. Complete surgical removal of the tumor, even in cases with metastasis or local invasion, offers an excellent prognosis. The overall 5-year survival rate can be greater than 97% after curative surgical resection.4The role of adjuvant therapy is largely experimental and its value has not yet been established. The use of radiotherapy has only been reported in 1 case5in which the tumor was considered unresectable because it involved the porta hepatis. That patient was free of disease at the 3-year follow-up.
Correspondence:Paul B. S. Lai, FRCSEd, MD, Division of Hepato-Biliary and Pancreatic Surgery, Prince of Wales Hospital, Chinese University of Hong Kong, Shatin, Hong Kong (email@example.com).
Accepted for Publication:June 14, 2005.
Image of the Month—Diagnosis. Arch Surg. 2006;141(8):832. doi:10.1001/archsurg.141.8.832