Cell block cellularity: A comparison of two fixatives and their impact on cellularity

Abstract

Background Ancillary testing including immunohistochemistry and molecular diagnostics has become an increasingly important component for the evaluation of cytologic specimens. Ancillary testing is important not only for diagnosis but also for predictive and prognostic evaluation. While a number of substrates are appropriate for ancillary testing, cell block specimens are commonly utilized and the success of ancillary testing depends on cell‐block cellularity. Methods Forty‐six pairs of cases each fixed in both formalin and CytoLyt were each analyzed by two evaluators for overall cellularity. Linear regression was used to assess inter‐rater reliability of cell counts for each method. Cellularity scores for each case were obtained by averaging the scores for each rater and cellularity was compared between the methods. Results Inter‐rater agreement was very good for both methods. The coefficient of determination was 1.0 and 0.99 for the CytoLyt and formalin methods respectively. Cell blocks using the CytoLyt method have lower levels of cellularity than cell blocks performed by the formalin method. Conclusions Cell blocks prepared using a formalin fixative yield significantly greater cellularity than those produced by the CytoLyt method. Formalin fixation appears to optimize cellularity of cell blocks useful for ancillary testing.

Multicenter randomized trial comparing diagnostic sensitivity and cellular abundance with aggressive versus standard biliary brushing for bile duct stenosis without mass syndrome

“…Such optimization of the standard brushing via previous biliary stricture dilation or biliary aspiration could explain the relatively high sensitivity rate of 67 % with the standard RX Cytology Brush in this study. Given that the solution used for cytological ▶ Table 3 Comparison of cellularity obtained between the two bru- examination was mainly CytoLyt (86 %), we could not interpret the influence of the solution used [28]. Targeted biopsies under cholangioscopic guidance do not achieve a sensitivity for cholangiocarcinoma of more than 70 %-80 % [12], a rate that can already be obtained by aggressive biliary brushing, as was the case in this study.…”

“…Such optimization of the standard brushing via previous biliary stricture dilation or biliary aspiration could explain the relatively high sensitivity rate of 67 % with the standard RX Cytology Brush in this study. Given that the solution used for cytological examination was mainly CytoLyt (86 %), we could not interpret the influence of the solution used [28].…”

Acinar cell induced autolysis is a frequent occurrence in CytoLyt‐fixed pancreatic fine needle aspiration specimens: An analysis of 157 cytology samples

“…However, it has more recently been shown to impair the immunoreactivity of some antibody clones including MIB1 and p16, among others 9‐11 . On the other hand, formalin has been found to be equally adept at preserving tissue both for diagnosis as well as immunocytochemical and molecular studies 1,8 …”

“…[9][10][11] On the other hand, formalin has been found to be equally adept at preserving tissue both for diagnosis as well as immunocytochemical and molecular studies. 1,8 A critical role of rapid tissue fixation is the preservation of cells for morphologic assessment and ancillary studies. Loss of morphological features due to poor tissue preservation can make microscopic evaluation challenging.…”

“…Cytology has become an increasingly important diagnostic tool for the evaluation of masses in a variety of organs, including the pancreas. 1 In particular, because of patient safety considerations, endoscopic ultrasound-guided (EUS) fine-needle aspiration (FNA) has become a mainstay in obtaining diagnostic material from pancreatic masses. 2,3 EUS-FNA is a minimally invasive procedure that is safe, effective, and accurate in pancreatic tumor diagnosis.…”