Pancreas

Other tumors

Pancreatoblastoma


Editorial Board Member: Aaron R. Huber, D.O.
Deputy Editor-in-Chief: Catherine E. Hagen, M.D.
Ryan Kendziora, M.D.
Lizhi Zhang, M.D.

Topic Completed: 22 July 2021

Minor changes: 22 July 2021

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PubMed Search: Pancreatoblastoma[TI] free full text[SB]

Ryan Kendziora, M.D.
Lizhi Zhang, M.D.
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Cite this page: Kendziora R, Zhang L. Pancreatoblastoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreaspancreatoblastoma.html. Accessed October 25th, 2021.
Definition / general
  • Rare pancreatic malignancy that is seen most often in children and displays multiple lines of differentiation
Essential features
  • Displays at least 2 pancreatic lines of differentiation, including acinar, ductal and neuroendocrine elements
  • Presence of squamoid nests is a defining diagnostic feature
  • Tumors are aggressive, with complete surgical resection being the most important prognostic factor
Terminology
ICD coding
  • ICD-O: 8971/3 - pancreatoblastoma
  • ICD-11:
    • 2C10.Y - other specified malignant neoplasm of pancreas
    • XH27L5 - pancreatoblastoma
Epidemiology
  • Children > adults
  • Only about 200 cases reported in the literature
Sites
Pathophysiology
  • Unknown
  • Loss of chromosome 11p or mutations in APC / B catenin pathway possibly implicated in pathogenesis (Gland Surg 2015;4:322)
Etiology
  • Unknown
  • Some cases associated with Beckwith-Wiedemann syndrome, familial adenomatous polyposis (Gland Surg 2015;4:322)
Clinical features
  • Generally nonspecific presentation; most common symptom is abdominal pain (Sci Rep 2020;10:11285)
  • Commonly advanced at presentation with local extension and metastases
    • Commonly metastasizes to liver > lymph nodes > lung
  • Associated with Beckwith-Wiedemann syndrome, familial adenomatous polyposis (Gland Surg 2015;4:322)
Diagnosis
  • Can be identified on CT or MRI
  • Difficult to diagnose by FNA due to variety of cell lines expressed (Gland Surg 2015;4:322)
Laboratory
  • Up to 50% of pediatric patients can show elevations in carcinoembryonic antigen (CEA) and alpha fetoprotein (AFP); less helpful in adults (Gland Surg 2015;4:322)
    • 66% of children will have AFP > 1000 μg/L
  • Some tumors reported to secrete adrenocorticotropic hormone (ACTH), resulting in Cushing syndrome (J Cancer Res Ther 2015;11:1027)
Radiology description
  • Generally solid, irregular lesion but can be cystic or degenerative
  • Can grow outward, as branches growing from a tree trunk (Sci Rep 2020;10:11285)
Radiology images

Images hosted on other servers:
Encapsulated heterogeneous mass with cystic components

Pancreatoblastoma, CT scan

Prognostic factors
  • Prognosis largely dependent on resectability of tumor (Pancreatology 2004;4:441)
    • 5 year survival for resectable tumors: 65%
    • 5 year survival for nonresectable tumors: 0%
  • Presence of distant metastases portends poorer prognosis
  • Prognosis worse in adults, as children tend to have well encapsulated tumors without metastases
Case reports
Treatment
  • Complete surgical resection is critical to prognosis
    • Chemotherapy or radiotherapy may be used to ensure complete resection
Gross description
  • Large (average size is 10 cm), lobulated, fleshy mass
  • Can have cystic components or soft areas of necrosis
Gross images

Images hosted on other servers:
Pancreatoblastoma, body / tail mass

Pancreatoblastoma,
body / tail mass

Encapsulated heterogeneous mass with cystic components

Encapsulated heterogeneous mass with cystic components

Microscopic (histologic) description
  • Multilineage components resembling embryologic pancreas
  • Geographic hypercellular solid tumor lobules separated by fibrous bands
  • Acinar differentiation is the predominant pattern, mimicking acinar cell carcinoma:
    • Acinar appearances resembling normal acini, with small lumen and luminal secretion
    • Focal solid, trabecular or pseudoglandular patterns
    • Cells with eosinophilic or amphophilic granular cytoplasm, mild atypical nuclei and small nucleoli
  • Squamoid nests:
    • Defining feature, present in every case
    • Plump to spindle shaped cells with abundant eosinophilic / clear cytoplasm arranged in whorls or nests
    • Typically bland cytology
    • May show keratinization
  • Neuroendocrine component:
    • More than 50% of cases show focal neuroendocrine differentiation
    • Neuroendocrine cells diffusely intermix with acinar component, being highlighted by immunostains or form focal organoid or trabecular growth
  • Ductal component:
    • Very focal glandular formation
    • May be highlighted by a mucicarmine stain
  • Primitive component:
    • Solid sheets of immature small round cells
  • Stroma:
    • Variable cellularity
    • Sometimes showing heterologous elements (e.g. bone, cartilage)
  • Reference: Am J Surg Pathol 1995;19:1371
Microscopic (histologic) images

Contributed by Lizhi Zhang, M.D.
Geographic tumor lobules

Geographic tumor lobules

Lobulated tumor nests

Lobulated tumor nests

Acinar differentiation Acinar differentiation

Acinar differentiation

Squamoid nests Squamoid nests

Squamoid nests


Squamoid nests with keratinization

Squamoid nests with keratinization

Neuroendocrine component

Neuroendocrine component

Ductal component

Ductal component

Primitive component

Primitive component

Stroma

Stroma

Caption

Keratin immunostain


Trypsin immunostain Trypsin immunostain

Trypsin immunostain

Beta catenin immunostain

Beta catenin immunostain

CK5 immunostain

CK5 immunostain

Synaptophysin immunostain

Synaptophysin immunostain

Cytology description
  • Loosely cohesive, blast-like tumor cells are small, with fine chromatin, granular cytoplasm and atypia with nucleoli (Cancer Cytopathol 2019;127:708)
    • Mimic acinar cell carcinoma
  • Squamoid nest cells can be well defined, whorled clusters or syncytial appearing groups (Cancer Cytopathol 2019;127:708)
    • Better appreciated on cell block preparations
Positive stains
Negative stains
Electron microscopy description
  • All showing zymogen granules (400 - 800 nm) for acinar differentiation (Am J Surg Pathol 1995;19:1371)
  • Some with neuroendocrine granules (125 - 250 nm) and mucigen granules (500 - 900 nm)
Molecular / cytogenetics description
Sample pathology report
  • Pancreas, duodenum and gallbladder, Whipple procedure:
    • Pancreatoblastoma, forming an 8 x 6 x 4 cm mass in the pancreatic head (see comment)
    • Tumor is confined within the pancreas without extension to peripancreatic soft tissue, common bile duct and duodenum
    • Tumor necrosis is present
    • Angiolymphatic and perineural invasion are present
    • All surgical margins are negative for tumor
    • Background pancreatic parenchyma is unremarkable
    • Multiple (3 of 14) regional lymph nodes are positive for metastatic tumor
    • Gallbladder is without diagnostic abnormality
    • Comment: Immunoperoxidase stains show the tumor cells are positive for trypsin with beta catenin nuclear staining in the scattered squamoid nests, confirming the diagnosis. Focal area is also positive for synaptophysin and chromogranin, representing a minor component of neuroendocrine tumor. No convincing component of ductal adenocarcinoma is seen.
Differential diagnosis
Board review style question #1

A 40 year old man presents with abdominal pain and unintentional weight loss. Subsequent imaging reveals an 8 cm mass in the pancreatic head invading into the duodenum and a likely metastasis in the liver. The patient undergoes neoadjuvant chemoradiation and a pancreaticoduodenectomy. A representative histology section is shown above. The cell population that most definitively identifies this diagnosis would be most specifically highlighted by which of the following immunohistochemical stains?

  1. Alpha fetoprotein
  2. Beta catenin
  3. Chromogranin
  4. Trypsin
Board review style answer #1
B. Beta catenin. Nuclear staining of beta catenin is a marker of alterations in the APC / beta catenin pathway, which commonly occurs in pancreatoblastoma associated with loss of chromosome 11p.

Comment Here

Reference: Pancreatoblastoma
Board review style question #2

A 5 year old boy presents with weight loss, abdominal pain and distention and hepatomegaly. An abdominal ultrasound reveals a pancreatic mass and multiple liver masses. A pancreas biopsy is performed. Based on the findings in the image shown above, what is the most likely diagnosis?

  1. Acinar cell carcinoma
  2. Malignant germ cell tumor
  3. Pancreatic neuroendocrine tumor
  4. Pancreatoblastoma
Board review style answer #2
D. Pancreatoblastoma. The characteristic squamoid nest shown in the image is a defining feature of pancreatoblastoma, present in every case.

Comment Here

Reference: Pancreatoblastoma
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