CASE 15

1. CASE 15 Xin Jing, M.D.

2. History • A 67-year-old male • A 1.3 cm round, well-defined, hypervascular pancreatic tail mass, incidentally detected by CT • Clinical/radiologic differential diagnoses: ― Endocrine tumors ― Serous cystic neoplasm ― Well-differentiated adenocarcinoma ― Solid-pseudopapillary neoplasm ―Acinic cell carcinoma • EUS-guided transgastric fine needle aspiration is undertaken

3. Endocrine Tumors • Uncommon pancreatic neoplasms (2%) • More common in older adults, F≈M • May be associated with hereditary syndromes (MEN type I, Von Hippel Lindau syndrome) • Most often involves pancreatic tail • Often identified incidentally by radiologic imaging (well-defined, homogenous, solid/cystic, calcification)

4. Typical Features: Cellular aspirates Loosely cohesive cell groups Pseudorosettes Uniform, round, polygonal, plasmacytoid cells Salt & pepper chromatin Other features: Single cells, cohesive sheets Other cell types: clear, oncocytic, spindled Cytoplasmic granules Bi-/multinucleation Nuclear pleomorphism Naked nuclei Endocrine Tumors

8. Serous Cystic Neoplasm • Almost universally benign • Microcystic variant ―Specific radiologic appearance (central scar, cysts with fibrous septae, “sunburst” type calcification) • Macrocystic variant(more likely to be aspirated) ―Non-specific radiologic findings ― Non-specific cytologic findings: paucicellular with loose clusters/sheets of bland glandular cells, clear background w/o extracellular thick mucin

10. Pancreatic Ductal Adenocarcinoma • Comprises 85-90% of all pancreatic carcinomas • Disease of older adults, M>F • Head->50% Body-15% Tail-5% Multifoci-20%

11. Well-differentiated Adenocarcinoma • Hypercellular aspirates • Numerous large two-dimensional sheets of cells • Unevenly distributed nuclei within the sheets-“drunken honeycomb” appearance • Ill- or well-defined cytoplasmic borders • Mild to severe nuclear atypia, low-high N/C ratios • Scattered atypical cells

15. Solid Pseudopapillary Neoplasm • A low grade neoplasm, accounts for 1% of all exocrine pancreatic neoplasms • Predominantly in adolescent girls & young women • Well-defined, solid/cystic mass in body or tail,calcification may be present

16. Solid Pseudopapillary Neoplasm • Hypercellular aspirates • Single cells, loose clusters, branching papillary fronds • Monotonous and bland cells • Scant-moderate, delicate cytoplasm, cytoplasmic processes • Mild nuclear atypia with granular chromatin & indistinct nucleoli • Intranuclear grooves • Myxoid, metachromatic stroma & hyaline globules • Rarely necrotic debris (cystic degeneration)

20. Acinar Cell Carcinoma • A rare malignant exocrine pancreatic neoplasm • Disease of older adults, M>F • Usually appears as well-circumscribed solid mass, rarely cystic mass • More common in the head of the pancreas

21. Acinar Cell Carcinoma • Cellular aspirates • Single cells & loose clusters with acinar formation • Abundant granular cytoplasm with indistinct cell borders • Central or eccentric nuclei with clumped chromatin & prominent nucleoli • Naked nuclei • Clean background

26. Immunostaining * PET (20-30%) may be positive ** SPT may be occasionally positive

27. Our Case

31. Our Case • Polymorphous population of lymphocytes mixed with other inflammatory cells ― Less likely a lymphoproliferative disorder • Was the needle placed into the lesion ― Yes • What about intensity of the mass (compared to pancreas and spleen) ― Similar to spleen

32. Our Case • Preliminary dx: ― C/w intrapancreatic accessory spleen

33. Accessory Spleen • A congenital abnormality with normal pancreatic tissue in ectopic sites • ~10% of autopsy cases • ~80% at/near splenic hilum <20% in/near pancreatic tail other sites: wall of jejunum/mesentery/pelvis • Usually an incidental finding • Rarely diagnosed preoperatively

39. Cytologic Features • Non-specific findings ― Predominantly small lymphocytes with a subset of histiocytes, conspicuous eosinophils, and plasma cells. • Characteristic CD8 positive immunostaining of endothelial cells in cell block.

40. Staining for CD8 - our case The case reported by Schreiner, et al

41. Take Home Message • A mass in/near pancreatic tail is not always a tumor • Include accessory spleen in your diagnoses • Use of EUS-guided FNA may provide a suggestive diagnosis and prevent unnecessary surgery

42. References • Chhieng DC, Stelow EB. Pancreatic Cytopathology. 2007. • Halpert B, Alden ZA. Accessory spleen in or at the tail of the pancreas: A survey of 2700 additional necropsies. Arvh Pathol 1964; 77:652-654. • Uchiyama S, et al. Intrapancreatic accessory spleen mimicking endocrine tumor of pancreas: case report and review of the literature. J Gastrointest Surg 2008; 12:1471-1473. • Kim SH, et al. Intrapancreatic accessory spleen: findings on MRI, CT, and US and scintigraphy, and pathologic analysis. Korean J Radiol 2008; 9: 162-174. • Schreiner AM, et al. Intrapancreatic accessory spleen: mimic of pancreatic endocrine tumor diagnosed by endoscopic Ultrasound-guided fine-needle aspiration biopsy. Diagn Cytopathol 2008; 36:262-265.

43. Acknowledgements • Claire Michael, M.D. • Stewart M. Knoepp, M.D., Ph.D. • Michael Roh, M.D., Ph.D. • Brian Smola, Sr. CT