Pancreas

Other tumors

Solid pseudopapillary neoplasm



Minor changes: 15 December 2021

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PubMed Search: Solid pseudopapillary tumor[TI] pancreas[TI] free full text[sb]

Pooja Navale, M.D.
Monika Vyas, M.D.
Page views in 2021: 31,921
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Cite this page: Navale P, Savari O, Tomashefski JF, Vyas M. Solid pseudopapillary neoplasm. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/pancreassolidpseudo.html. Accessed January 21st, 2022.
Definition / general
  • Low malignant potential tumors with unclear cell of origin and pathogenesis
  • May be derived from pluripotent stem cells of the genital ridges that become attached to the pancreas during embryogenesis (Semin Diagn Pathol 2014;31:484)
  • First described by V.K. Frantz in 1959; incorporated into the WHO classification in 1996 (Br J Surg 1959;47:334)
Essential features
  • Presents in younger women, classically as solitary body / tail mass
  • Variable amount of solid and cystic areas grossly
  • Papillary fronds on myxoid or hyalinized vascular stalk lined by poorly cohesive, uniform cells with nuclear grooves comprising solid and cystic areas beta catenin nuclear / cytoplasmic positive
Terminology
  • Also known as solid pseudopapillary tumor, papillary epithelial neoplasm, papillary cystic neoplasm, solid and papillary neoplasm, low grade papillary neoplasm and Hamoudi or Frantz tumor
Epidemiology
Sites
Clinical features
  • Most common symptoms are abdominal pain and a palpable, nontender, upper abdominal mass
  • Also symptoms related to an intra abdominal mass effect, such as discomfort, nausea, vomiting and early satiety
  • However, most cases are incidentally discovered on imaging
  • Reference: Arch Pathol Lab Med 2017;141:990
Diagnosis
  • Young woman with a well circumscribed, solid cystic mass in the body / tail of pancreas
  • Cyst fluid chemistry shows low CEA and amylase (Ann Gastroenterol 2013;26:122)
Laboratory
Radiology description
  • Well circumscribed, encapsulated, heterogeneous pancreatic lesion with cystic degeneration on CT or MRI
Radiology images

Contributed by Omid Savari, M.D.

MR of abdomen



Images hosted on other servers:

Hypodense lesion

Endoscopic ultrasound

Multiple metastases

Prognostic factors
  • Poor prognostic factors include: size > 5 cm, male gender, necrosis, cellular atypia, vascular invasion, perineural invasion and invasion into adjacent structures (Dig Liver Dis 2013;45:703)
Case reports
Treatment
  • Surgical resection is curative in > 95% of cases
Gross description
  • Range from 0.5 to 34.5 cm, with a mean diameter of 6 cm
  • Well defined, encapsulated, with variable amount of solid and cystic patterns
  • Smaller lesions tend to be more solid but less sharply circumscribed
  • Larger tumors demonstrate a fibrous pseudocapsule and have a variegated and friable cut surface
  • Cystic degeneration and hemorrhage are common findings in larger specimens
  • Rarely, may extend into adjacent structures, such as duodenum
  • Reference: Arch Pathol Lab Med 2020;144:829
Gross images

Contributed by Omid Savari, M.D., Dr. Andreas Schulz, Manfred Stolte, M.D., Dr. Helmut Luchtrath and Case #121

Predominately solid tumor

Partially necrotic tumor

Invasion of spleen

Cystic lesion

Multilocular cystic mass

Microscopic (histologic) description
  • Tumors are heterogeneous, with variable admixture of solid and pseudopapillary areas
  • Solid areas are comprised of uniform cells admixed with capillary sized blood vessels
  • Pseudopapillae are formed due to tumor cells getting detached from blood vessels forming fibrovascular stalks or rosette-like structures (Arch Pathol Lab Med 2020;144:829)
  • Stroma usually shows various degrees of hyalinization or evidence of degeneration, such as hemorrhage, foamy macrophages, calcification and cholesterol clefts
  • Tumor cells usually have a moderate amount of eosinophilic cytoplasm with intracytoplasmic hyaline globules (PAS+ and diastase resistant, positive for alpha-1-antitrypsin) and perinuclear vacuoles (Am J Surg Pathol 2011;35:981)
  • Relatively uniform nuclei with finely textured chromatin, inconspicuous nucleoli and characteristic longitudinal grooves
  • Variants include clear cell, oncocytic and pleomorphic
  • Rare mitotic figures
  • Although grossly well circumscribed, microscopic finding of infiltration to the surrounding pancreatic tissue is not uncommon
  • Rare cases of highly aggressive behavior; histological features in those cases included diffuse growth pattern, extensive necrosis, significant nuclear atypia, high mitotic count (35 - 70/50 high power fields) or sarcomatoid features (Am J Surg Pathol 2005;29:512)
Microscopic (histologic) images

Contributed by Monika Vyas, M.D., Omid Savari, M.D. and Raul S. Gonzalez, M.D.

Pleomorphism and cytologic atypia

Intracytoplasmic eosinophilic hyaline globules

Tumor infiltration by foamy histiocytes

Solid pseudopapillary neoplasm



Solid pattern

Clear cell changes

Cholesterol cleft, scattered giant cells

Tumor invading parenchyma



Beta catenin

CD10

Ki67

Metastasis to liver

Cytology description
  • Cellular smears with delicate papillary fronds
  • Tumor cells are usually bland and uniform with a moderate amount of cytoplasm, which usually contains variable sized clear perinuclear vacuoles or cytoplasmic eosinophilic hyaline globules
  • Nuclei are round to oval with grooves and finely granular chromatin (J Cytol 2010;27:118, Arch Pathol Lab Med 2017;141:990)
  • Cercariform cells, cytoplasmic vacuolation, reniform nuclei, hyaline globules and degenerative features, such as cholesterol crystals, calcifications, foam cells or giant cells, are more commonly seen in solid pseudopapillary neoplasms, compared with acinar cell carcinomas / neuroendocrine tumors (Cancer Cytopathol 2013;121:298)
Cytology images

Contributed by Omid Savari, M.D.

Diff-Quik

Pap

Cell block

Positive stains
Negative stains
Electron microscopy description
  • Mitochondria rich cytoplasm with electron dense granules and rough endoplasmic reticulum
Electron microscopy images

Contributed by Dr. H.D. John, Mainz

Abundant mitochondria

Granules

Molecular / cytogenetics description
  • Point mutation in exon 3 of β catenin gene (CTNNB1) is present in > 90%
  • Gene mutation results in the accumulation of β catenin in the cytoplasm and formation of a β catenin Tcf / Lef complex, through which the Wnt signaling pathway activates several oncogenic genes, such as MYC and cyclin D1 (Am J Clin Pathol 2017;149:67)
  • Rarely, mutations in APC gene (also associated with familial adenomatous polyposis) have been described (Pathol Int 2019;69:193)
Sample pathology report
  • Pancreas and spleen, distal pancreatectomy and splenectomy:
    • Solid pseudopapillary neoplasm (XX cm), confined to pancreas (see comment)
    • Resection margins are free of tumor
    • Unremarkable spleen, (x g)
    • X benign lymph nodes (0/12)
    • Comment: Immunohistochemical stains show the neoplastic cells are positive for CD10 and exhibit nuclear expression of beta catenin while negative for synaptophysin and chromogranin.
  • Pancreas, mass, biopsy:
    • Epithelial neoplasm, most consistent with solid pseudopapillary neoplasm (see comment)
    • Comment: By immunohistochemistry, the neoplastic cells are positive for CD56, pancytokeratin (focal) and show rare focal positivity for synaptophysin while being negative for chromogranin. Aberrant nuclear expression of beta catenin is present. The histologic and immunohistochemical findings are in keeping with a solid pseudopapillary neoplasm.
  • Pathological staging (AJCC 8th edition) - similar to exocrine pancreatic tumors
Differential diagnosis
Board review style question #1
What is the most common gene mutation in pancreatic solid pseudopapillary neoplasm?

  1. CTNNB1
  2. KIT
  3. PDGFRA
  4. RAS
Board review style answer #1
A. Somatic point mutation of β catenin gene (CTNNB1) is present in > 90% of pancreatic solid pseudopapillary neoplasms

Comment Here

Reference: Solid pseudopapillary neoplasm
Board review style question #2

What is the composition of intracytoplasmic hyaline globules in solid pseudopapillary neoplasms?

  1. Alpha-1-antitrypsin
  2. Fibrinogen
  3. Glycogen
  4. Mucin
Board review style answer #2
A. The hyaline globules are immunoreactive for alpha-1-antitrypsin and are also PAS+ and diastase resistant

Comment Here

Reference: Solid pseudopapillary neoplasm
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