Among rare primary tumors of the pancreas we remember:

• Acinar Cells Carcinoma: although pancreatic acinar cells represent more than 80% of pancreatic tissue, acinar cell accounts only for 1% of primary pancreatic neoplasms (with the majority of patients being men). The tumors are usually large, well circumscribed with an inner nodular pattern, frequently involving the pancreatic head although jaundice is very rare. Occasionally “Schmid’s triad” is present (subcutaneous fat necrosis, polyarthralgia, eosinophilia). It may be associated with elevated serum levels of CEA, Ca19.9 and occasionally AFP. Radiological features are non-specific, the differential diagnosis includes ductal adenocarcinoma, pNETs and solid pseudopapillary tumors (the appearance is usually an hypodense mass with a well-defined enhancing capsule and intratumoral calcifications or necrosis). They are malignant tumors with an unfortunate prognosis, the therapy of choice is resection whenever possibile, even if neoadjuvant chemotherapy has yelded good results.

• Pancreatoblastoma: an extremely rare pancreatic tumor mostly occurring during childhood (in wich is the most common pancreatic neoplasm), although several cases in adults has been described. This tumor can also be seen in association with Beckwith-Wiedemann syndorme. It uusually present with upper abdominal pain and often a palpable epigastric mass, weight loss is charateristic. One-third of patients already presents with metastases at the time of diagnosis, most commonly in the liver. Complete surgical resection is the best treatement for localized tumors.

• Primary Pancreatic Lymphoma: tipically a non-Hodgkin’s abdominal lymphoma, is very rare, comprising <0.5% of pancreatic tumors and 1% of all extranodals lymphoma. A cytopathologic diagnosis by fine-needle aspiration is of paramount importance, because the primary treatment is non-surgical, based on a combination of chemo- and radio-therapy (unfortunatly it may initilly mimic pancreatic adenocarcinoma). Increased LDH serum level helps clarify the diagnosis. 

• Hepatoid Carcinoma: this tumors are extrahepatic neoplasms exhibiting morphologic and immunohistochemical features of hepatocellular carcinomas. Fewer than 20 have been reported. They can present in pure forms, more indolent, or in association with other morphological aspects.