Despite the presence of squamoid nests, pancreatoblastomas are negative for squamous markers (negative for high molecular weight keratins CK14, CK5/6, and CK17) and CK7 (179) but positive for CK8, CK18, CK19, EMA and cytoplasm and membranous β-catenin (180). Up to half of the tumors

may exhibit neuroendocrine differentiation with focal chromogranin and synaptophysin positivity while the cells of ductal differentiation are highlighted by their production of mucin, Inhibitors,research,lifescience,medical CEA and CA19 positivity (181). Pancreatoblastomas have also been found to show alterations in the β-catenin/APC pathway in up to 80% of cases, hence its positivity by immunohistochemistry (180). Acinar cell carcinoma Acinar cell carcinoma is more common in adults and presents with non-specific gastrointestinal symptoms such as abdominal Inhibitors,research,lifescience,medical pain, nausea and weight loss. Some patients may have subcutaneous fat necrosis and SB939 supplier polyarthralgia due to increase

levels of serum lipase (159). These tumors are often large and can occur anywhere within the pancreas but are more often found at the head of the pancreas. Microscopically, acinar cell carcinomas show nests of pyramidal cells arranged in solid or acinar patterns. Tumor cells have basally oriented nuclei, single prominent nucleoli Inhibitors,research,lifescience,medical and granular cytoplasm. Acinar cell carcinomas are positive for pancytokeratin, CK8, CK18, zymogen, trypsin, chymotrypsin and lipase, but negative for CK7 and CK19 (182,183). Scattered cells positive for neuroendocrine markers are present in one-third of cases. A few cases may demonstrate the APC/β-catenin gene mutation (184). Mixed exocrine-endocrine tumors Inhibitors,research,lifescience,medical Mixed exocrine-endocrine tumors are defined as malignant epithelial neoplasms where the ductal and endocrine cells are intimately mixed in the primary tumor with at least one-third to one-half of tumor cells showing positivity for endocrine Inhibitors,research,lifescience,medical markers (185). Ductal differentiation is defined

as ductular formation and mucin production (174) and presence of ductal markers like CEA, CK19 and CA19.9, while ductal acinar cells can be highlighted by pancreatic enzymes like trypsin, chymotrypsin and lipase (186,187). Endocrine cells can be characterized by positivity aminophylline for endocrine markers chromogranin A and synaptophysin. These mixed tumors generally behave as ductal adenocarcinomas (187). It is important to remember that 40-80% of usual ductal adenocarcinomas may contain endocrine cells, but the metastases from these tumors generally lack endocrine cells (174,187). Liver Primary tumors of the liver are divided into epithelial and non-epithelial (mesenchymal) lesions and then further into benign and malignant categories. The majority of the mass lesions within the liver are benign lesions such as focal nodular hyperplasia (FNH), regenerative nodules, adenoma, cirrhosis, and vascular lesions.