[444] Cytomorphology, Cyst Fluid Analysis and Molecular Tests in Pancreatic Cystic Lesions: Review of 459 Cases

Berrin Ustun, Ahmed Alomari, Gillian H Levy, David Chhieng, Harry R Aslanian, Uzma Siddiqui, Guoping Cai. Yale University School of Medicine, New Haven, CT

Background: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is increasingly used to evaluate cystic lesions of the pancreas. It is however quite difficult to accurately diagnose these lesions due to scant cellularity and subtle cytomorphologic features. Cyst fluid analysis and molecular tests may help improve diagnostic performance. In this study, we retrospectively reviewed our experience with cystic pancreatic lesions diagnosed by EUS-FNA.
Design: The electronic data of cytopathology archives were searched for pancreatic lesions diagnosed by EUS-FNA at our institution during the period from January 2005 to June 2011. A total of 1,143 cases were retrieved, of which 459 cases (40%) were cystic lesions. The cytomorphologic diagnoses and the results of cyst fluid analysis (amylase and CEA levels) and molecular tests (K-ras mutation, loss of heterozygosity [LOH] of tumor suppressor gene alleles) were reviewed. Histopathologic follow-up was available for comparison in 81 cases.
Results: The cytomorphologic diagnoses included non-diagnostic (48 cases, 10%), negative (127 cases, 28%), bland/cyst contents (160 cases, 35%), atypical (26 cases, 6%), pancreatic endocrine neoplasm (6 cases, 1%), mucinous cystic neoplasm (84 cases, 18%), and malignant (8 cases, 2%). Elevated CEA level (>=192 ng/ml), positive K-ras mutation and LOH were found in 25 of 79 (32%), 49 of 137 (36%), and 54 of 94 (53%) cases, respectively. Histopathologic follow-up was compared with cytomorphologic diagnoses (Table 1) as well as the results of cyst fluid analysis, K-ras mutation and LOH test (Table 2).

Table 1. Correlation between Histopathologic and Cytopathologic Diagnoses

	Cytological Diagnosis
Histopathology	Non-diagnostic	Negative	Bland/Cyst	Atypical	PEN	MCN	Malignant
Negative (13)	0	3	8	0	0	2	0
PEN (6)	1	0	0	0	5	0	0
IPMN (31)	2	3	7	4	0	11	4
MCN (28)	1	8	12	1	0	6	0
Malignant (3)	1	0	0	0	0	0	2
Total (81)	5	14	27	5	5	19	6

PEN, pancreatic endocrine neoplasm; IPMN, intraductal papillary mucinous neoplasm; MCN, mucinous cystic neoplasm

Table 2. Correlation between Histopathologic Diagnosis and Ancillary Studies

	CEA		K-ras Mutation		LOH
Histopathology	< 192 ng/ml	>=192 ng/ml	Negative	Positive	Negative	Positive
Negative	1	0	1	1	1	0
PEN	2	0	2	0	1	0
IPMN	1	3	8	6	3	5
MCN	0	7	8	8	3	8
Malignant	0	1	1	0	1	0
Total	4	11	20	15	9	13

LOH, loss of heterozygosity


Conclusions: Our data demonstrate that cyst fluid analysis and molecular tests are complementary to cytomorphologic evaluation and should be incorporated in the final cytological diagnosis of pancreatic cystic lesions.
Category: Cytopathology

Tuesday, March 20, 2012 8:00 AM

Platform Session: Section F, Tuesday Morning