Solid cystic and papillary tumor of the pancreas with oncocytic differentiation

Pancreatic Solid Pseudopapillary Neoplasm: Key Pathologic and Genetic Features

CONTEXT.—

Solid pseudopapillary neoplasm of the pancreas is a low-grade malignant tumor generally associated with a good prognosis. Solid pseudopapillary neoplasms show peculiar morphologic features, but sometimes the differential diagnosis with other pancreatic neoplasms (ie, pancreatic neuroendocrine tumors) can be a challenging task, especially in cytologic or biopsy specimens. In these cases immunohistochemistry is a useful tool, but the diagnostic utility of several proposed immunohistochemical markers is questionable. In recent years, despite several attempts to characterize the pathogenetic, molecular, and prognostic features of solid pseudopapillary neoplasms, they still remain unclear.

OBJECTIVE.—

To give the reader a comprehensive update on this entity.

DATA SOURCES.—

The PubMed database (US National Library of Medicine) was searched using the following string: pseudopapillary tumor [AND/OR] neoplasm [AND/OR] pancreas. All articles written in English were included. In addition, because a heterogeneous terminology has been used in the past to define solid pseudopapillary neoplasms, the reference lists of each paper selected in the PubMed database were also reviewed.

CONCLUSIONS.—

This review gives a comprehensive update on the pathologic, clinical, and molecular features of solid pseudopapillary neoplasms, particularly addressing issues and challenges related to diagnosis. In addition, we have tried to correlate the molecular alterations with the morphologic and clinical features.

Nonductal Pancreatic Cancers

Nonductal pancreatic neoplasms, including solid pseudopapillary neoplasms, acinar cell carcinomas, and pancreatoblastomas, are uncommon. These entities share overlapping gross, microscopic, and immunohistochemical features, such as well-demarcated solid neoplasms, monotonous cellular tumor cells with little intervening stroma, and abnormal beta-catenin expression. Each tumor also has unique clinicopathologic characteristics with diverse clinical behavior. To differentiate nonductal pancreatic neoplasms, identification of histologic findings, such as pseudopapillae, acinar cell features, and squamoid corpuscles, is important. Immunostainings for acinar cell or neuroendocrine markers are helpful for differential diagnosis. This article describes the clinicopathologic and immunohistochemical features of nonductal pancreatic cancers.

Pancreatic analogue solid pseudopapillary neoplasm arising in the paratesticular location. The first case report

We describe the first pancreatic analogue of solid pseudopapillary neoplasm arising in paratesticular location. It was a tumor arising in 32-year-old man adhering closely to the testis. The tumor had several morphologic components. The greatest was represented by signet ring cells which gradually changed into solid, non-signet ring cell areas, often being mixed together. It also formed distinct trabeculae and pseudopapillae frequently adhering to cystic areas of the tumor. Immunohistochemically, the tumor had an identical profile to its pancreatic counterpart. The tumor cells reacted diffusely with S100 protein, β-catenin, cyclin D1, Fli-1, vimentin, CD10, galectin-3, and neuron-specific enolase and focally with synaptophysin. CD56 and E-cadherin reacted only in those parts of the tumor, which formed pseudopapillae. Cytokeratin antibody AE1-AE3 was strongly positive in the areas of trabecular formation of the tumor. The mutational analysis of exon 3 of the CTNNB1 gene confirmed mutation in this exon.

Non-cystic solid-pseudopapillary tumor of the pancreas showing nuclear accumulation and activating gene mutation of beta-catenin

Solid-pseudopapillary tumor (SPT) is an unusual pancreatic neoplasm that is characterized by a mixture of solid and cystic components and a fibrous capsule. Recently, the tumorigenesis of SPT has been reported to be associated with gene mutations of beta-catenin, which is a molecule participating in the Wnt signaling pathway. Reported herein is the case of a 53-year-old woman with SPT. The tumor, approximately 3 cm in diameter in the pancreas body, had a clear margin and central calcification but had neither a cystic component nor fibrous capsule. Several lines of pathological findings in the surgically resected specimen indicated SPT: (i) pseudopapillary proliferation of eosinophilic polygonal cells with oval nuclei; (ii) positive expression of several marker molecules indicating differentiation into acinar and endocrine cells; and (iii) zymogen granule-like structures in the cytoplasm on electron microscopy. Further, the tumor cells had intense nuclear accumulation of beta-catenin and an activating mutation, (34)Gly(GGA) to Arg(AGA), in exon 3 of the beta-catenin gene, as previously reported in most SPT. These findings suggest that association of the beta-catenin phenotype with development of the rare phenotype of SPT, a non-cystic and unencapsulated tumor, is unlikely.

The Clear Cell Variant of Solid Pseudopapillary Tumor of the Pancreas: A Previously Unrecognized Pancreatic Neoplasm

Solid pseudopapillary tumor is a rare but distinctive pancreatic neoplasm whose cell phenotype remains a mystery. We report 3 cases of a previously undescribed variant of solid pseudopapillary tumor of the pancreas composed almost entirely of multivacuolated clear cells (>90%). The cytoplasmic vacuoles did not contain glycogen, mucin, or lipid but seemed to be formed by dilatation of the endoplasmic reticulum and mitochondria. The tumors displayed prominent trabeculae and a solid growth pattern but lacked the characteristic pseudopapillary pattern of the classical solid pseudopapillary tumor. In contrast, the clinical features, gross characteristics, and immunoprofile were similar to those of classical solid pseudopapillary tumor. Two of the patients were young adult females with well-demarcated tumors involving the body and tail of the pancreas. Tumor cells showed immunoreactivity for vimentin, CD10, CD56, synaptophysin, and nuclear accumulation of beta catenin. In 2 patients, 1 male and 1 female, the tumors were discovered incidentally. Despite vascular invasion in one of the tumors all 3 patients are disease free after distal pancreatectomy. Clues to distinguish the clear cell variant of solid pseudopapillary tumor from endocrine pancreatic tumor composed of clear cells, clear and foamy cell variants of ductal carcinoma, metastatic renal cell carcinoma, serous cystadenoma and ectopic adrenocortical nodules are provided.

Lipid-Rich Variant of Pancreatic Endocrine Neoplasms

Most pancreatic endocrine neoplasms (PENs) show characteristic and well-recognized endocrine morphology; however, a lipid-rich pattern, which can present a diagnostic problem in biopsies, has been reported, mostly as individual cases. Some have been included in descriptions of the rare clear-cell variant associated with von Hippel-Lindau (VHL) syndrome. The histogenesis, clinicopathologic characteristics, and significance of this lipid-rich pattern have not been unraveled. In this study, 11 PENs exhibiting foamy, microvesicular cytoplasm were analyzed. In some cases, the nuclei were distorted by the vesicles, and the usual endocrine chromatin pattern was not evident. The growth pattern was relatively diffuse, with vague compartmentalization of the cells by a delicate vasculature; prominent nesting was noted in only 4 cases. Pathology reports indicated substantial diagnostic challenge in these cases; on biopsies, 1 case was originally diagnosed as adrenal cortical carcinoma, another as renal cell carcinoma, a third as solid-pseudopapillary tumor, and a fourth had a fine needle aspiration cytologic diagnosis of adenocarcinoma. All cases were chromogranin and synaptophysin positive. Electron microscopy in 3 cases confirmed the cytoplasmic vesicles to be lipid vacuoles. Neurosecretory granules were also evident. Clinically, as in conventional PENs, there appeared to be two distinct subsets: Two cases were familial or functional/syndromic (1 with VHL and the other with MEN-1 and glucagonoma syndrome) and occurred in younger adults (ages 41 and 47 years); the majority (n = 9) were nonfunctional/nonsyndromic and nonfamilial. The latter group was mostly represented by elderly males (mean age: 65 vs. 58 years in conventional sporadic PENs). Immunohistochemically, markers implicated in VHL-associated neoplasia, including HIF-1alpha, inhibin, and Melan-A (in clear-cell PENs) and MUC6 (in serous cystadenomas) were mostly negative in lipid-rich PENs (1 of 10, 1 of 10, 0 of 10 and 0 of 10, respectively). In conclusion, the lipid-rich pattern, reminiscent of adrenal cortical cells, represents a distinct subset of PENs. It presents a diagnostic challenge for surgical pathologists, especially in biopsies. EM supports the name lipid-rich for this variant. The findings suggest that the pathogenesis of lipid-rich tumors may be different from the VHL-associated clear-cell variants of PENs.

Solid and cystic tumor of the pancreas: clinicopathologic and genetic studies of four cases

BACKGROUND

Solid and cystic tumor (SCT) of the pancreas can be distinguished from other pancreatic neoplasms by its nearly exclusive occurrence in young women, and its favorable prognosis after complete resection.

METHODS

We experienced four cases with SCT of the pancreas, and analyzed these tumors by immunohistochemical and electron microscopic studies, as well as genetic analysis of ras oncogene mutation.

RESULTS

The presented cases expressed the neuron-specific enolase in two cases, alpha1-antitrypsin and alpha1-antichymotrypsin in two cases, and vimentin in one case, which indicated that this tumor originates from pleuripotential embryonic stem cells. No patients had mutations of K-ras gene in codon 12, and further genetic analysis is required to predict the malignant potential.

CONCLUSION

SCT of the pancreas appears to have limited malignant potential and the metastatic ratio is not high, although the tumor has local invasion. Therefore, an aggressive surgical approach seems fully justified.

Giant solid cystic tumor of the pancreas with a fibrous septum caused by extracapsular growth in middle-aged woman: report of a case

We report herein the case of a 57-year-old female who was admitted to our hospital for treatment of rectal carcinoma and incidentally found to have a giant cystic tumor, 20 cm in diameter, in the body and tail of the pancreas. Several imaging procedures, including ultrasonography, computed tomography, and magnetic resonance imaging, showed that this tumor was round and hypovascular, and had a septum with protuberant lesions. The capsule was 3-4 mm thick with partial calcification. A preoperative diagnosis of a solid cystic tumor (SCT) of the pancreas was made, even though these tumors are rarely found in females in their fifties. Moreover, few reports of SCT with a septum have been described. Distal pancreatectomy and splenectomy were performed, and the tumor was found to be filled with massive necrotic tissue. Microscopically, the tumor was confirmed to be a SCT with a fibrous septum. We present this case due to the atypical findings, including the age of the patient and the existence of a septum caused by extracapsular growth.

Solid and papillary tumor of the pancreas: ultrastructural observations on two contrasting cases

Two papillary and solid tumors of the pancreas are reported which differed in their clinical features, ultrastructure, and biologic behavior. Both tumors contained papillary and solid areas by light microscopy. One tumor followed the more usual indolent course. The second patient presented with a liver metastasis and died of progressive disease in a relatively short period of time. Neither neoplasm showed convincing immunohistochemical or ultrastructural evidence of endocrine differentiation, but the electron microscopic findings hinted that this tumor possesses at least latent endocrine properties.