Solid Pseudopapillary Neoplasm of the Pancreas: Arjun Mehta, MD, Wafaa Elatre, MD

23 year old female who presented to the ED with abdominal pain was found to have a 9.0 cm mass in the body and tail of pancreas without evidence of ductal obstruction or involvement. Attached are the photomicrographs

 

PAP stained images show numerous vascular channels with tumor cells “budding” off the capillaries. The individual cells display eccentrically placed nuclei and slender cytoplasmic projections.

  

H&E stained image shows pseudopapillae comprised of capillary cores bordered by tumor cells
 
B- Catenin                            CD10                               PR
IHCs: Beta catenin (nuclear positive) , CD10 (Membranous staining) , Progesterone receptor (Nuclear positive)

Definition

  • Low grade, malignant epithelial tumors with uncertain cellular differentiation
  • First described by V.K Frantz in 1959

Essential features

  • Presents in young women, classically as large body / tail mass
  • Variable amount of solid and cystic formation at gross exam
  • Papillary fronds on myxoid or hyalinized vascular stalk lined by poorly cohesive, uniform cells with nuclear grooves comprising solid and cystic areas
  • β-catenin 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

  • Represents 1-2% of pancreatic neoplasms
  • Mainly young females are affected – the female to male ratio is 10:1
  • Usually presents in the third to fourth decade of life (mean age 35 years)
  • In men tends to occur at an older age with more aggressive behavior (Surgery 2008;143:29)

Sites

Clinical features

  • The most common symptoms are abdominal pain and a palpable, non-tender, upper abdominal mass
  • Also symptoms related to an intra-abdominal mass effect, such as discomfort, nausea, vomiting and early satiety

Laboratory

Radiology description

  • Well circumscribed, encapsulated, heterogeneous pancreatic lesion with cystic degeneration on CT or MRI

 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)

Cytology description

  • Cellular smears with delicate papillary fronds
  • Tumor cells 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;27:118Arch Pathol Lab Med 2017;141:990)

Positive stains

Negative stains

 Molecular / cytogenetics description

  • Point mutation in exon 3 of β-cateningene (CTNNB1) is present in more than 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 MYCand Cyclin D1 (Am J Clin Pathol 2017;149:67)