Cytologically Yours: Unknowns: 201401: Case 2

Cytology

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Resident Questions

• Diagnosis?

• Pancreatic Endocrine Neoplasm
  • Include Islet cell tumor and pancreatic carcinoid tumors
  • Approximately 5% of pancreatic neoplasms
  • Most commonly seen in both male and female adults between 40-60 years old but can occur at any age
  • Small (1-5 cm) well circumscribed lesion may look cystic on imaging
  • Commonly seen in the tail of the pancreas
  • Can be part of Multiple Endocrine Neoplasia-1, von Hipple-Lindau disease, Neurofibromatosis type 1, Tuberous Sclerosis Complex

• What are some of the cytologic features that lead you to the diagnosis?

• Cellular smear with singly dispersed uniform cells
• Loosely cohesive or discohesive uniform cells
• Cells are uniform, plasmacytoid with abundant finely granular cytoplasm
• Background is clean
• Occasional pleomorphism can be seen
• Round/oval bland cells with salt and pepper chromatin

• Differential diagnosis?

• Acinar cell carcinoma
  • Clusters, acinar groups and single cells with abundant granular cytoplasm and prominent nucleoli
  • Lack salt and pepper chromatin
  • Positive staining for trypsin, chymotrypsin and alpha-1-antichymotrypsin
  • Negative for neuroendocrine markers
• Solid Pseudopapillary Neoplasm
  • May see hyaline globules and clear cytoplasmic vacuoles
  • Branching papillary clusters with distinct central fibrovascular cores, but this can be seen in PEN too
  • Positive for vimentin, CD10, beta catenin, neuron specific enolase, CD56
  • Negative for keratin markers
• Plasmacytoma
  • Look for a perinuclear hof and clock face chromatin
  • Positive staining for CD138
  • Negative for neuroendocrine markers
• Islet cell hyperplasia
  • Difficult/ impossible to distinguish from islet cell tumor by cytology alone
• Melanoma
  • Can see melanin pigment in the cytoplasm but not always
  • Melanoma cytomorphology can be quite diverse
  • Positive for MART-1, HMB45, MITF
  • Negative for neuroendocrine markers

• What ancillary studies would you order?

• Neuroendocrine markers
  • CD56
  • Synaptophysin
  • Chromogranin
• Cytokeratin
• TTF-1
• Markers specific to peptide production