PTU-043 Prospective Study of the Diagnostic Yield from Histological Versus Cytological Preparation of Specimens Acquired Using Standard EUS FNA Needles

Abstract

IntroductionImprovements in the EUS FNA needle design and optimisation of tissue acquisition techniques have resulted in better diagnostic yield (DY). Recently there has been considerable interest in histological processing of tissue acquired using newer ‘core’ FNA needles, which are often more expensive than standard needles.We hereby provide preliminary data on DY of tissue acquired using standard FNA needles.AimTo compare the diagnostic yield of histological versus cytological preparation of tissue acquired using standard EUS FNA needle and to compare overall diagnostic yield.MethodsProspective non-blinded randomised study .All patients undergoing EUS guided FNA from November 2015 to February 2016, for solid lesions were included. FNA was performed using Cook Echotip UltraTM or Boston Scientific ExpectTM 19, 22 or 25 G needles based on stock availability and location of the lesion, Olympus EU-ME2TM processor and linear echoendoscopes was used.All patients had 4 passes done with the same needle, specimens from each pass were randomly collected in BD CytorichTM or Formalin. Each preservative had 2 passes of material. EUS FNA was performed by one endosonographer and two trainees employing standard FNA technique and suction, pathology reported by 5 different cytopathologists. All cytology specimens were processed by the biomedical scientists for cell block ± smear preperation. Cellularity of the sample were simply graded as adequate or inadequate. Histology processing was performed as standard.ResultsIn total 21 patients had EUS FNA performed, mean age 65.5±12.1 years, 14 M:7 F. Final diagnoses include 5 pancreatic malignancies, 5 GIST/NET, 2 malignant nodes, 1 lymphoma, 6 benign, 2 non-diagnostic. 19 G needle was used in 15 patients, 22 G in 4 patients and 25 G in 2 patients.Diagnosis was made in 15/21 (71.4%) from cytology specimens and 19/21 (90.4%) from combined cytology and histologically processed specimens. An incremental diagnostic gain in 4/21 specimens, i.e. 19% by processing samples as histology in addition to standard cytology. No statistical significance was seen on univariate or multivariate logistic regression analysis for tumour size (≥2 cm), route of FNA or size of needle.Limitations of the study include small sample size, no blinding being used for randomisation of the FNA specimen.ConclusionOur ‘proof of concept’ study with preliminary results show that adequate samples can be obtained for histological processing even with standard FNA needles and incremental gain in DY by additionally processing specimens as histology. Data from our randomised blinded trial would shed further light into this important area.Disclosure of InterestNone Declared