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Mixed tumors

Reviewer: Deepali Jain, M.D. (see Reviewers page)
Revised: 25 November 2012, last major update August 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.


● Significant amount (some authors-25%) of each component
● “Collision tumours” have 2 topographically separate neoplasms, and are not considered "mixed"

Proposed classification system for mixed tumors

Mixed acinar-ductal
● Either (a) acinar component with extensive cytoplasmic or extracellular mucin pools, with positive mucin (mucicarmine, Alcian blue) and acinar (trypsin, chymotrypsin) staining or (b) ductal pattern of individual gland infiltration with desmoplasia, but acinar differentiation by IHC (WHO)
● Highly aggressive (Am J Surg Pathol 2010;34:510)

Mixed acinar-ductal carcinoma

Top-ductal elements (right) are glandular and contain intracellular mucin; acinar elements (left) are arranged in large nests
Bottom-acinar cells stain with trypsin, mucin associated with ductal cells stain with Alcian blue

Mixed acinar-endocrine tumor
● Behaves like acinar cell carcinoma
● For these tumors, diagnosis should be based on morphology, not immunohistochemistry, because endocrine tumors may routinely stain with acinar markers (Am J Surg Pathol 2002;26:893, Am J Surg Pathol 1994;18:765)
● Resembles pancreatoblastoma
Case reports: 74 year old man (Cases J 2009;2:6481)

74 year old man

Mixed ductal-endocrine
● Either (a) intermingled neoplastic ductal and neuroendocrine cells forming glandular/squamoid and solid structures, or (b) moderately differentiated neoplastic ductal structures embedded in solid neuroendocrine component (WHO)
● Must rule out trapped benign ducts within an endocrine tumor
● By definition, does not include ductal adenocarcinoma with scattered endocrine cells (see images below)
Case reports: 58 year old man with tumor types separated by fibrous band (Arch Pathol Lab Med 2000;124:284), 65 year old woman (JOP 2005;6:449), 74 year old man with mixture of tumor types (Arch Pathol Lab Med 2000;124:284)

Left: poorly differentiated carcinoma, middle: endocrine component stains with somatostain; right: PAS-diastase (purple) highlights mucin, somatostain highlights endocrine component

65 year old woman with 12 cm tumor that infiltrated spleen and splenic vessels
Line 1: ductal component is well differentiated and CA 19-9 positive
Line 2: endocrine component has irregular islands with central necrosis, is chromogranin+, synaptophysin+

Separation of tumor types by fibrous band

Various images-mixture of tumor types

Not a mixed tumor - well differentiated adenocarcinomas with scattered endocrine cells: left-synaptophysin+, right-tail tumor has numerous PP+ endocrine cells

Mixed acinar, ductal, endocrinel tumor
● Use immunohistochemistry to define
● Aggressive clinical course (Am J Surg Pathol 2010;34:510)
Case reports: 21 year old man (Pathol Int 1995;45:669), 56 year old man (Int J Clin Exp Pathol 2009;2:602)

56 year old man

End of Pancreas > Tumors > Mixed tumors

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