How do I diagnose NETs?

G N RameshASTER Medcity

Cochin

Nomenclature • Arising from Enterochromaffin cells • Differentiation / grading• ‘Carcinoids’ are the well differentiated tumors• Poorly differentiated tumors are referred to as

Neurendocrine carcinomas – small cell or large cell .

• Further nomenclatures are related to the origin and stage – foregut , midgut , hindgut , pancreatic , metastatic , functioning / non-functioning

Classification by origin

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Size is important

Clinical presentations

Case 1 : RB

• 56 yr old male with generalised abdominal pain . OGD – ‘severe PUD with gastric ulcers”

• Repeat OGD – large mass at angularis , erythematous mucosa with shallow ulceration

• CT – distal gastric mass - submucosal

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When to suspect?

• Multiple gastric lesions• Gastric lesions in patients with pernicious

anemia / chronic atrophic gastritis / MENs • Gastric growth which is not an

adenocarcinoma

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Jejunoileal NETs• Increased detection on endoscopy and

imaging• 60s and 70s ; arise from intraepithelial

endocrine cells• Most commonly located – distal 60 cms of

ileum • Abd pain 40% ; intermittent obstruction 25% ;

duodenal/biliary obstruction , intussusception • Metastasis – liver 47% if primary >2 cms ;

nodes 58% if primary > 1 cm

Appendix NET

• Most common neoplasm of the appendix• Incidental detection ; most often tip / distal

third of appendix ; 10 % base of appendix – obstruction

• 40s – 50s ( younger profile) – appendectomy related ; younger women who undergo pelvic surgeries

• Carcinoid syndrome related to metastasis

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Midgut NETs – when to suspect?

• Vague small bowel pain with mass• Carcinoid syndrome • Appendicitis with mass • Base of appendix tumor• Intussusception / mass with desmoplastic

reaction• Ulcerated small bowel growth • Multiple small bowel lesions

Hindgut NETs

• Usually nonsecretory , not associated with carcinoid syndrome even when metastatic

• Symptoms – mimic adenoca - altered bowel habits ; obstruction ; bleeding

Colonic NETs

• Elderly patients – 70s• Presentation – usually ‘adenoca like’• Rarely functional • Majority – rt colon particularly caecum • Symptoms related to size – ave size at

detection – 5 cms • 2/3 – local nodal / distant metastasis

Rectal NETs• Asymptomatic – found on colonoscopy • 60s• Uncommon manifestations – bleeding ; changed

bowel habits ; pain ;• Carcinoid syndrome very rare • 75-85% are localised – no mets• Size more than 2 cms – 25% metastasise to liver• Poor prognosis related to size , invasion into

muscularis propria , lymphovascular invasion , high mitotic rate ( > 2 per 50 HPF)

Hind gut NETs – when to suspect?

• Colonic growth that is not an adenoca• Rectal polyps ( submucosal) with or without

ulceration• Small colonic / rectal primary with multiple

large liver mets

When to suspect PNETs?

• Clinical syndromes • Well defined rounded lesions in the pancreas• Symptoms of excessive hormone production

Suspicion

Clinical Imaging – endoscopic/radiologic

Staging / origin CT / MRI + EUS DOTATATE scanning

Histology Resection / FNA / Biopsy

Markers Chromogranin A / Pancreatic polypeptide / both

Functioning / non-functioning Insulin / glucagon / VIP / gastrin

CT

• Most NETs are highly vascular ; enhance in arterial phase (20s ) ; washout in portal venous phase (70s ) .

• > 80% sensitivity • Small tumors – rounded enhancing lesions ,

some may be hypodense or cystic .• Non-functionin symptomatic lesions are often

larger > 3 cms

MRI

• Typically – low signals on T1 ; high signals on T2

• Sensitivity 85% ; specificty 100% ; PPV 100% ; NPV 73%

• Better for hepatic lesions

68 Ga – DOTATATE PET-CT imaging

• Improved detection and staging on P-NETs• Increased sensitivity for smaller lesions• Higher spatial resolution• Preferred over OCTREOSCAN

More studies

• Transhepatic portal venous sampling ( THPV)• Arterial stimulation and venous sampling

( ASVS )• Intraoperative Ultrasound • Hormonal studies

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