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GASTROINTESTINAL STROMAL TUMORS (GIST) IN NEUROFIBROMATOSIS 1 (NF1) PATIENTS: A CLINICOPATHOLOGIC ANALYSIS OF NINE CAS PowerPoint Presentation
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GASTROINTESTINAL STROMAL TUMORS (GIST) IN NEUROFIBROMATOSIS 1 (NF1) PATIENTS: A CLINICOPATHOLOGIC ANALYSIS OF NINE CAS

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GASTROINTESTINAL STROMAL TUMORS (GIST) IN NEUROFIBROMATOSIS 1 (NF1) PATIENTS: A CLINICOPATHOLOGIC ANALYSIS OF NINE CASES. Elena Fumagalli, Paola Coco, Elena Palassini, Palma Dileo,  Rossella Bertulli, Paolo G. Casali . Istituto Nazionale Tumori Milan, Italy. This series.

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slide1

GASTROINTESTINAL STROMAL TUMORS

(GIST)

IN NEUROFIBROMATOSIS 1 (NF1) PATIENTS:

A CLINICOPATHOLOGIC ANALYSIS

OF NINE CASES

Elena Fumagalli,

Paola Coco, Elena Palassini, Palma Dileo, 

Rossella Bertulli, Paolo G. Casali

Istituto Nazionale Tumori

Milan, Italy

this series
This series
  • 5 females : 4 males
  • Median age 51 yrs (range 36-59)
  • Localized disease in all cases, with multiple lesions in 6 pts
  • Site:
    • stomach and duodenum 1pt
    • duodenum 2 pts
    • jejunum 1 pt
    • ileum 4 pts
    • other 1 pt
  • Risk stratification:
          • high 2 pts
          • intermediate 1 pt
          • low/very low 6 pts
this series pts with multifocal disease
This series: pts with multifocal disease
  • 6/9 pts
  • (5 low risk, 1 high risk)

2 pts

4 pts

slide5

“The presence of multiple GIST in NF1 might reflect

a distinct rate-limiting step in oncogenesis

compared with sporadic GIST. While a broad spectrum

of inactivating genetic mechanism might lead to

suppression of the wild type NF1 allele and GIST

formation in NF1 pts, only a limited set of specific

activating mutations in KIT/PDGFRA will result in

sporadic GIST”

this series molecular genetics
This series: molecular genetics

8 pts: WT

1 pt (gastric + duodenal GIST):

PDGFRA exon 18 (D842V) mutation in the gastric GIST; WT in the duodenal GIST

slide7

Immunohistochemistry

D842V in exon 18 of PDGFRA

G A G WC AT C A

PDGFRA

D842V

affecting the A-loop of PDGFRA

slide9

KIT/PDGFRA

KIT/PDGFRA

slide10

This series: pts with NET

1 pt: pheochromocytoma

1 pt: pheochromocytoma

+ ampullary neuroendrocrine tumor

neuroendocrine tumour

pheocromocitoma

slide13

SUV 4.5

SUV 4.7

slide17

FDG PET distinguishes

MPNSTs

from benign neurogenic tumours

with 100% sensivity

and 83% specificity

at an SUV cut-off value = 1.8

  • SUV level predicts outcome

in NF1 pts with MPNSTs

  • SUV cut-off value = 3
  • No correlation with

histological grading

slide18

Significant difference between

mean SUV of malignant and

benign tumours

  • Overlap with SUVmax = 2.5-3.5

 lesions should be reviewed

clinically

  • Time for measuring SUV 240 min
  • FDG PET and PET TC is

sensitive and specific

for MPNST in NF1 pts

  • Research with different tracers to predict tumour grade
this series prognosis
This series: prognosis

8 pts: alive and well

median follow-up = 23 months (range = 6-97 months)

1 pt: metastatic disease (baseline: >5 cm; >10/50 HPF)

 death after progression to Imatinib

this series secondary resistance
This series: secondary resistance

1 pt (ileal GIST):

Kit exon 17 (D820N) mutation in metastatic lesions;

WT in primary tumour

D820N cKit ex 17

immunohistochemistry

A G A AT r AT T

cKIT

Mussi et al. Clin Cancer Res 2008:14 July 15

slide25

Conclusions

  • Only anecdotal cases of GIST have been reported in NF1, though in the face of a 5-10% risk of developing the disease in this syndrome
  • WT are predominant, but KIT/PDGFRA mutations are occasionally present (both to KIT and PDGFRA)
  • NET may be concurrent, in the face of a 1% risk of these diseases in NF1
  • Prognosis of WT GIST in NF1, although multifocal, is good, but may be worse for KIT/PDGFRA-mutated GIST
  • AntiTK are often ineffective, but responses have been occasionally reported (and secondary resistance may arise)
  • GIST in NF1 are often positive on PET scan, but specificity may be problematic against other lesions, including neurofibromas