Neuroendocrine tumors of GI and Pancreatobiliary tracts. N. Volkan Adsay, MD

Neuroendocrine tumors of GI and Pancreatobiliary tracts N. Volkan Adsay, MD

New (2017) WHO

WHO 2017 (endocrine book; for pancreas)

WHO 2017 (endocrine book; for pancreas) PD-NE ca WD-NE Tumor Intended to be used also for GI NETs

Change # 1: Tumor vs Carcinoma further clarified (but still problematic)

I have a metastatic NE neoplasm in the liver, what do I call it?

How do we report a NET in the liver?

CASE: WD neuroendocrine neoplasm in the liver DIAGNOSIS: METASTATIC WELL-DIFFERENTIATED NEUROENDOCRINE TUMOR*, GRADE 1 Comment: This tumor is a WDNET. It is NOT a PD carcinoma (not a high grade neuroendocrine carcinoma). Mitotic activity is < 2/10 ; Ki67 < 2% (Grade 1 of 3).

Change #2: Ki67 > 20% can be tumor OR carcinoma

Change #3: Ki67 between 2 and 2.99 is G1 (not G2)

Change #3: Ki67 between 2 and 2.99 is G1 (not G2) ~ 15% of PanNETs fall to this 2-3% range (Reid, M. Modern Pathol, 2014)

WDNETs Diagnostic pitfalls

WDNET Diagnostic problems Crush artefacts (in biopsies) Atypical patterns Especially tubular patterns Chromogranin-A negativity (common in appendiceal and rectal ones)

Problem: Limited bx - Mucosal component can be small - Artifacts common

Degenerated gland appearance

Ampullary tumor: Original dx, adenoca. Pitfall: Glandular patterns

Ampullary somatostatinoma ( GLANDULAR psammomatous carcinoid )

Ampullary somatostatinoma Glandular psammomatous carcinoid Glandular pattern Psammoma bodies Neurofibromatosis LN metastasis in % 50-70 (despite their small size )

Intraluminal mucin may be prominent, but no convincing intracytoplasmic mucin

Tubular WDNET (carcinoid) of appendix

PanNETs: Morphologic spectrum is wider than appreciated In addition to the classical nested and trabecular patterns

PanNETs: Nucleoli may be prominent on cytology

Lipid-rich PanNETs:

Oncocytic PanNETs: Probably more aggressive

Pleomorphic Variant of PanNET: Has no clinical significance Note single plasmacytoid cells and cells with focal degenerative endocrine atypia

CHROMOGRANIN CHROMATIN

Benign ducts can be prominent in PanNETs (NO significance) CK19 (good ductal marker)

Ductulo-insular PanNET

WDNETs Determinants of outcome; Reporting

Determinants of biologic behavior in GI WDNETs ( carcinoids ) 1. Location 2. Cell type 3. Clinical setting, syndromic background 4. Size (stage) 5. Grade 6. Adjunct histologic/biologic parameters

Most appendiceal classical WDNETs (carcinoid) are asymptomatic Most are microscopic; 2% of autopsies Most rectal ones are non-metastatic Most < 1 cm Ileal or colonic: Mets are common Most are advanced at diagnosis

Determinants of biologic behavior in NETs 1. Location 2. Cell type / hormonal status Most insulinomas are benign but they are also small at diagnosis (> 70% are < 1 cm). Most glucagonomas are malignant but they are also higher stage (large; >3 cm) at diagnosis 3. Clinical setting, syndromic background 4. Size (stage) 5. Grade 6. Adjunct histologic/biologic parameters

Determinants of biologic behavior in GI NETs ( carcinoids ) 1. Location 2. Cell type 3. Clinical setting, syndromic background 4. Size (stage) 5. Grade 6. Adjunct histologic/biologic parameters

The importance of clinical setting Example: Gastric NETs Type I (hypergastrinemia-related / ELC cell) Typically benign course Type II (ZE or MEN syndrome) Type III (Sporadic) Typically aggressive

Stomach- Enterochromaffin-like cell lesions Etiology Atrophic gastritis Medication Gastrinoma Hypo or achlorhydria Sustained hypergastrinemia Genetic factors? ELC Hyperplasia ELC Dysplasia ELC NET (carcinoid)

Enterochromaffin- like cell lesions in the stomach Hyperplasia Rare cells Linear Micronodular

Dysplasia Nodules > 150 microns Conglomerated micronodules Microinfiltration in the lamina propria New stroma ENETS /TNM proposal: Tis (In-situ tumor/dysplasia); Vanoli et al, Human Pathol, 2013

SP Report If it is all composed of tiny clusters Stomach, bx: ELC-cell proliferation in the background of atrophic gastritis If it also shows conglomerated, large clusters Minute WDNET of type A (see comment), arising in the background of ELC-cell proliferation and atrophic gastritis

Type A or type 1 carcinoid (NET)

The importance of clinical setting Example: Gastric NETs Type I (hypergastrinemia-related / ELC cell) Typically benign course Type II (ZE or MEN syndrome) Type III (Sporadic) Typically aggressive

Determinants of biologic behavior in NETs 1. Location 2. Cell type 3. Clinical setting, syndromic background 4. Stage (depth, size and mets) 5. Grade 6. Adjunct histologic/biologic parameters

Determinants of biologic behavior in GI NETs 1. Location 2. Cell type 3. Clinical setting, syndromic background 4. Size (stage) 5. Grade 6. Adjunct histologic/biologic parameters

WHO 2017 (endocrine book; for pancreas)

Problems with Ki67: How to count?

Problems with Ki67: How to count? 1. Refuse to count? 2. Eyeballing 3. Counting # of cells by live microscope 4. Have the machine count it (automated) 5. Have someone else count it 6. Counting # of cells by static field pictures from a computer

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing (guess-timating)

Results of eye-balling of Ki67 index by 18 observers in 45 cases illustrates striking inter-observer variability (as well as grade variability)

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing About 60 % of the cases have an index close to the categorical cut-offs: Only ~ 5% are in the extremes (< 1% and > 30%) Reid et al. Mod Pathol. 2014

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing 3. Counting # of cells by live microscope

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing 3. Counting # of cells by live microscope 4. Have the machine count it (automated)

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing 3. Counting # of cells by live microscope 4. Have the machine count it (automated) Machine also counts: Hemosiderin Lymphocytes Endothelial cells Etc

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing 3. Counting # of cells by live microscope 4. Have the machine count it (automated) 5. Have someone else count it

Problems with Ki67: How to count? 1. Refuse to count 2. Eyeballing 3. Counting # of cells by live microscope 4. Have the machine count it (automated) 5. Have someone else count it Counting # of cells by static field pictures from a computer

Manual count on camera-captured-printed image is the most applicable approach (practical and accurate) in daily life

37 (pos) --------------------------- 361 (37 pos + 324 neg) 10%

Current Surg Path Report Ileum; resection: - Well differentiated neuroendocrine tumor (classical carcinoid), Grade 1 of 3 in the WHO-2010 classification (see comment). Size: 2 cm Depth of invasion: Deep in muscularis propria VI: - ; PNI: - Margins: - LNs: 0/14. AJCC-stage: T2, N0; ENETS-Stage: T2, N0 Comment: - Mitotic activity: 1/10 HPF - Ki-67: 1.8 % - Neuroendocrine markers: Not performed (classical carcinoid)

Beyond WDNET. NET-3 vs PDNEC

Well-differentiated PanNET (2 examples)

(Morphologically) Well-differentiated but Ki67 > 20%

(Morphologically) Well-differentiated but Ki67 > 20%: [ GRADE DISCORDANT NE TUMOR] Diagnosis: Well-differentiated PanNE TUMOR, grade 3 of 3 by Ki67 proliferation index Comment: NET-3 (per WHO 2017) NOT a PDNEC Reference: Basturk et al, Am J Surg Pathol, 2014 Basturk et al, Am J Surg Pathol, 2015

Poorly differentiated NE carcinoma

IHC for confirming NE differentiation Chromogranin Synaptophysin CD56 (cautiously) But, NOT NSE or others It is advisable to have the support of at least one of these markers in order to distinguish true NECs from incomplete examples or its mimickers

PD NE carcinoma (ki67 typically > 50%) Diagnosis: Poorly differentiated neuroendocrine carcinoma Reference: Basturk et al, Am J Surg Pathol, 2014 Basturk et al, Am J Surg Pathol, 2015

Poorly diff NEC- Problem: DDx from other PD neoplasms Focal NE differentiation in the classical carcinomas. Poor prognosis? Poorly differentiated carcinoma, NOS Medullary carcinoma Basaloid/cloacogenic-type squamous ca Melanoma Sarcomas with epithelioid features

Poorly diff NECs of GI/PB Often associated with conventional adenocarcinoma and adenoma component Most are not transformation of WD-NET Aggressive behavior (worse than ordinary carcinomas of respective sites). Small cell therapy protocol may work better than ordinary ca protocols (inadequate data).

And then there are the tougher ones

Ambiguous group : WD? PD? Ki67 20-50%

Loss of RB; positivity of P53: PDNEC If present, loss of ATRX/DAXX: WDNET Rb loss Tang et al, Am J Surg Pathol. 2016 Jun 1

Conclusions NENs can display unusual morphologies that ought to be kept in mind All NENs are malignant neoplasms (although incipient precursor lesions do occur but difficult to define) WDNETs ought to be graded and staged as any other malignancy WHO 2017 clearly distinguishes WDNET from PDNEC based on the morphology (not Ki67)

Conclusions Grade-discordant NETs (well-diff by morphology but Ki67> 20) now has a specific home as WDNET-G3 G3 NEN does NOT mean PDNEC Ambiguous cases (in between WDNET and PDNEC) do occur Associated w/ increased aggressive behavior relative to G1/2 tumors but better than G3 PDNEC New molecular/ihc markers (p53, Rb, DAXX, ATRX) can help with classification

CASE FOR DISCUSSION Appendiceal tumor: relatively intact wall; layers preserved

A subtle infiltrate of very well-formed glandular units

Composed of goblet cells; very similar to colonic crypts

Classical Goblet cell carcinoid Is it really a carcinoid? Chromogranin, only focal Ordinary carcinoid pattern is very very uncommon If low-grade/low-stage (confined to the appendix), behaves like a carcinoid (prognosis is good)

THIS CASE ALSO SHOWED Compressed, ill-defined, irregular glandular units

Areas with stromal mucin deposition was prominent

Mucin was associated with disorganized neoplastic cells

CHROMOGRANIN

CASE -Diagnosis ADENOCARCINOMA EX-GCC APPENDICEAL CRYPT CELL ADENOCARCINOMA WHO: Mixed GCC-adenocarcinoma

Distinctive features of adenoca ex GCC (appendiceal crypt cell adenocarcinoma) allow it to be recognized as an appendiceal primary even in metastatic sites: 1. Goblet cells (with voluminous pale-basophilic cytoplasm) 2. Crypt like structures 3. Small clusters of goblet cells 4. Microglandular units

Small glandular units composed of goblet type cells

Signet-ring like cells with voluminous cytoplasm, in small clusters: Most likely appendiceal (less likely gastric)

Especially if they form small, round glandular elements

Small round glands resembling crypts, even if without goblet cells: Still, highly suggestive of appendiceal origin

NEGATIVE < 10% 10-75% DIFFUSE (> 75%) Chromo 47 31 14 4 Synapto 36 36 22 6 CD56 71 22 15 2

NEGATIVE < 10% 10-75% DIFFUSE (> 75%) Chromo 47 31 14 4 Synapto 36 36 22 6 CD56 71 22 15 2 Appendiceal crypt cell adenocarcinoma (Adenocarcinoma ex-goblet-cell- carcinoid ) is NOT a neuroendocrine tumor

Morphologic ddx is upper- GI (gastric) carcinoma signet-ring like cells small tubular configuration IHC: Lower-GI profile CDX2 98% MUC2-76% CK20-90% Upper GI markers mostly negative: (MUC1 11%, MUC5AC 20%, MUC6 2%; CK7 16%).

Conclusion Adenocarcinoma ex-gcc is NOT a neuroendocrine tumor per se, but rather an appendiceal type adenocarcinoma with cyrpt cell differentiation

Determining the site of origin of a metastatic NET Is it needed? Is it possible?

Determining the site of origin of a NET Often not possible; lots of overlaps Often not necessary WD-NET is a perfectly adequate diagnosis Don t be cornered by your clinicians to commit Imaging studies (octreotide scan and PET) and serologic studies (serotonin etc) are very successful in identifying the primary Having said that, few site-specific patterns do exist (and good to be aware of)

NET in the pancreas:

CDX2 Islet is negative

Isl1 (islet-1)

Ileal tumor resected subsequently

The current impression on the sitespecificity of the markers Yang et al, AJSP, July, 2017,