Analysis of KIT mutation and protein expression in fine needle aspirates of gastrointestinal stromal/smooth muscle tumors.
OBJECTIVE
To determine if sequencing the KIT gene could facilitate more definitive FNA diagnosis.


METHODS
Sixteen cases of gastrointestinal stromal/smooth muscle tumor (GIST) in which fine needle aspiration (FNA) was performed (mean age, 67; M/F = 12/4) were studied. DNA was extracted from cytologic preparations from all patients (15 cell blocks, 1 alcohol-fixed smear) and seven subsequent resection specimens. DNA was amplified by polymerase chain reaction, using primers designed to amplify a segment of the KIT gene exon 11 and sequenced on an ABI Prism 377 DNA sequence analyzer (Applied Biosystems, Indianapolis, Indiana, U.S.A.). Immunocytochemical staining for CD 117 (the KIT gene product) was performed on sections from 12 cell blocks and 7 surgical resections.


RESULTS
In-frame deletion of exon 11 was detected in eight cases (7 monoalleic, 1 bialleic); a point mutation was found in one case. Mutation was found only in histologically malignant (6 of 10 cases) and borderline GISTs (3 of 4 cases). No mutation was identified in benign tumors. In three cases, scant cellularity or blood precluded sequencing. CD 117 was expressed in 12 of 15 cases.


CONCLUSIONS
Immunocytochemical staining for CD 117 is useful in confirming a cytologic diagnosis of GIST but does not facilitate diagnosis of malignancy. FNA biopsy specimens are suitable for KIT gene sequencing; detection of a KIT mutation favors a malignant diagnosis, though absence of mutation does not preclude malignancy.
Li
S Q
SQ
Department of Pathology, Columbia University College of Physicians and Surgeons, VC 14-215, 630 West 168th Street, New York, New York 10032, USA. sl828@columbia.edu
O'Leary
T J
TJ
Sobin
L H
LH
Erozan
Y S
YS
Rosenthal
D L
DL
Przygodzki
R M
RM
D000328:Adult; D000368:Aged; D001707:Biopsy, Needle; D004247:DNA / Q000032:analysis / Q000302:isolation & purification; D004252:DNA Mutational Analysis; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008637:Mesenchymoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism
D004247:DNA; D019009:Proto-Oncogene Proteins c-kit