Endoscopic ultrasound fine needle aspirate DNA analysis to differentiate malignant and benign pancreatic masses.
OBJECTIVE
Accurate diagnosis of malignant and benign pancreatic masses can be challenging, potentially delaying treatment for cancer and subjecting patients with benign disease to unnecessary surgery. Endoscopic ultrasound fine needle aspirate (EUS-FNA) of pancreatic masses remains inconclusive in a subset of patients. The role of EUS-FNA molecular analysis in this context is studied.


METHODS
Patients with benign pancreatic masses (6 cases, 4 autoimmune pancreatitis, 2 focal chronic pancreatitis) and malignant pancreatic masses (15) with inconclusive cytology (5 cases) and positive cytology (10 controls) were selected. All cases had definitive pathology. Representative cells were microdissected from each EUS-FNA sample and subjected to PCR for analysis of 16 microsatellite allele loss markers situated at 1p, 3p, 5q, 9p, 9q, 10q, 17p, 17q, 21q, and 22q. Loss of heterozygosity analysis used fluorescent capillary electrophoresis for quantitative determination of allelic imbalance. k-ras-2 point mutation analysis was also performed. Mean fractional mutation rate (FMR) was calculated and compared for each group.


RESULTS
All malignant cases carried multiple mutations (FMR 0.50), regardless of positive cytology (FMR 0.52) or suspicious cytology (FMR 0.47) (p = NS). Five of the 6 benign cases carried no mutations whereas 1 case of autoimmune pancreatitis and coexisting PanIN lesions exhibited a k-ras mutation (FMR 0.01). The mean FMR for the malignant and benign samples was significantly different (p < 0.0001).


CONCLUSIONS
Broad panel microsatellite loss and k-ras point mutation analysis can be reliably performed on EUS-FNA samples from pancreatic masses and improves the diagnostic accuracy. Furthermore, it accurately differentiates between malignant and benign pancreatic masses.
Khalid
Asif
A
Department of Medicine, The University of Pittsburgh and VA Pittsburgh Health Care, PA 15213, USA.
Nodit
Laurentia
L
Zahid
Maliha
M
Bauer
Kathy
K
Brody
Debra
D
Finkelstein
Sydney D
SD
McGrath
Kevin M
KM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001327:Autoimmune Diseases / Q000175:diagnosis; D044963:Biopsy, Fine-Needle / Q000379:methods*; D003937:Diagnosis, Differential; D019160:Endosonography; D005260:Female; D011905:Genes, ras / Q000235:genetics; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D010182:Pancreatic Diseases / Q000175:diagnosis*; D010190:Pancreatic Neoplasms / Q000175:diagnosis*; D010195:Pancreatitis / Q000175:diagnosis; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies