liquid - based cytology ( lbc ) as a technique was introduced and tried on pap smears .
thereafter , this technique was performed for non - gynecological cytology , including conventional fine needle aspiration cytology ( fnac ) , guided fnac and fluid cytology .
the thin - prep ( tp ) smears were consistently devoid of obscuring elements and the cells were adequately preserved and evenly dispersed .
pitfalls noticed as cytomorphologic alterations in lbcs are small - sized cell clusters , with more single cells than sheets .
the cells are generally smaller , occasionally show spindling , chromatin detail is attenuated , nucleoli are more prominent , intranuclear inclusion is difficult to visualize , decrease of extracellular particles is seen , there is a decrease in the number of small mononuclear cells / red blood cells / myoepithelial cells and the background matrix is altered
. the pathologist should be cautious in interpreting fine needle aspirations prepared using tp if that is the only methodology employed .
the advantages of lbc , independent of diagnostic accuracy and morphology , have been well described .
although studies on lbc are documented for breast , non - gynecological specimen , thyroid , salivary gland and soft tissues , the authors supplemented bone lesions to all the above in their study .
lbc in fnac smears can be performed on aspirates from different organs like salivary gland , thyroid , lymph nodes , breast , bone and soft tissue and other usual and guided fnac samples .
processing of the samples is carried out using the tp kit , marketed by cytec corporation , malborough , ma , usa . in a comparison study , usually two passes are made .
the first pass is performed for the conventional preparation ( cp ) and the second pass is for the tp preparation .
tp smears are superior to cp smears in fnac ; this fact can be proved by performing a wilcoxon 's signed rank test , p value < 0.001 .
tp preparations are nowadays used in some sophisticated investigations like immunohistochemistry studies in breast lesions , non - hodgkin 's lymphoma ( nhl ) and hodgkin 's lymphoma ( hl ) in effusions , analysis of proliferating cell nuclear antigen ( pcna ) , cell blocks from scraping of cytosmears and comparison with conventional cell blocks .
the aim of our study was to determine the efficacy of lbc technology over conventional smear methods in fnac samples .
the study was performed on patients attending the cytology outpatient department ( opd ) of the hospital over a period of 2 years .
, samples were processed using the liquiprep processing kit and a special kit marketed by cytec corporation .
processing was performed manually in three steps , i.e. collection , concentration and cellular encapsulation .
the lp cytology processing kit contains a preservative solution and a cellular base . using the lbc processing kit ,
, the samples were pushed into a preservative solution , approximately three - times the volume of the sample , and left as such for at least 1 h. this is followed by the next step , i.e. concentration , where the preserved sample is centrifuged at 3000 rpm for 30 min . for cystic fluids , the supernatant fluid is discarded and , after adding the cleaning solution , it is again centrifuged for 15 min to increase its concentration .
a pellet is produced , the supernatant fluid is discarded and a base solution of about 50 microl is added to the pellet to make a thin , homogenous suspension .
this suspension was placed on an ethanol - cleaned glass slide and two circular smears of 1 cm diameter were made .
the second option , which uses a cellular base solution , was used in certain cases , particularly if the sample contains necrotic substance or mucin .
about 4 ml of cleansing solution was used in selected cases , along with the preservative solution , and the processing was performed in a similar fashion .
two passes were performed , the first pass was for cp and the second pass yielded material for the tp preparation , which was processed by the tp kit marketed by cytcec corporation .
different stains were used for staining the cp and lp smears , like he , pap and diff quick .
the representative cs and lb preparations were compared by a semiquantitative scoring system using several criteria [ table 1 ] .
the concentration method used in the procedure was useful in the diagnosis of cystic lesions like aneurysmal bone cysts , warthin 's tumor of salivary glands and metastatic carcinoma .
statistical analysis was performed using the wilcoxon signed rank test on the spss program ( chicago , il , usa ) .
every cytological diagnosis was recorded and tabulated and compiled to yield the p - value .
a total of 110 cases were studied , which were distributed among 30 cases of breast ( 10 fibroadenoma , four mastitis and 12 ductal carcinoma ) , 40 cases of lymph node ( 20 reactive hyperplasia , 12 granulomatous lymphadenitis , three lymphoma and five metastatic carcinoma ) , 10 cases of salivary gland ( two sialadenitis , five mixed tumor , one warthin 's tumor and two mucoepidermoid carcinoma ) , 18 cases of thyroid ( 10 colloid goiter , four thyroiditis and four carcinoma cases ) and 12 cases of soft tissue and bone lesions ( five benign and seven malignant ) .
comparison between cytological features in lbc and cs was carried out using the wilcoxon signed rank test separately for each organ in a tabular form , as shown in table 2 . in our study , in two cases of pleomorphic adenoma , one case of warthin 's tumor and two cases of colloid goiter , a support of cs was needed due to pitfalls in lbc described above .
wilcoxon signed rank test statistics of lbc versus cp for breast cases , fibroadenoma , mastitis and ductal carcinoma were better diagnosed on lbc preparations due to clarity of the nuclear features [ figure 1 ] .
comparison data for lymph nodes suggested that the rs cells were more easily diagnosed on lbc smears due to monolayering .
liquiprep cytosmear of the breast showing pleomorphic - looking ductal epithelial cells in a cluster and acinar pattern in a clear background in case of salivary gland lesions , the mixed salivary tumor was better visualized in the conventional smear because of preservation of the stromal component .
cystic neoplasms of the salivary glands were better appreciated in lbc smears because of concentration . in sialoadenitis ,
lbcs were not very useful in goiter and infectious lesions , but they proved very useful in neoplastic lesions [ figure 2 ] . in lytic bone lesions like aneurismal bone cyst ( abc ) , giant cell tumor ( gct ) and metastasis ,
liquiprep cytosmear showing papillary carcinoma of the thyroid in a clear background with nuclear grooving the study conducted by mygdakos et al .
lbc was favored over cs for evaluating gynecological specimens , which was approved by the fda in 1996 .
thereafter , lbc has been found to be useful in non - gynecological cytologic specimens like fnac and body fluids , both small and large volume , which have drawn variable conclusions . in conventional fnac
smears , cells are admixed with debris , blood and exudates , which make the interpretation difficult .
there is suboptimal preservation of cells and cellular obscuring by unwanted material , leading to a high proportion of cases reported as inadequate or unsatisfactory for assessment . to overcome this problem , the lbc technique was introduced , which preserves cells in a liquid medium and removes all debris , blood and exudates , either by filtration or density gradient interpretation
, there is even distribution of cell material , lack of obscuring factors , no drying artifact and monolayering . in our study , fnac was performed from various sites like breast , lymph node , salivary glands , thyroid and bone and soft tissue . in fibroadenoma breasts , although stromal fragments were lost , lbc proved to be useful in the diagnosis based on visualization of ductal aggregates and bipolar cells . for duct carcinomas ,
the wilcoxon signed ranked test for thyroid lesions [ table 2 ] , lbc was not useful in goiter and infectious lesions .
lbc was not useful in cystic neoplasms like warthin 's tumor , mucoepidermoid and adenoid cystic carcinoma and comparable to the study by parfitt et al . for bone and soft tissues , good results were obtained in lbc because of background clearing and concentration phenomenon . in all lesions of the lymph node ,
lbc proved to be a better option . because of the pitfalls of lbc , as described above , in some selected cases of granulomatous lymphadenitis ( lacking epitheloid cells ) , mucinous tumors ( lack of mucin ) , colloid goiter ( thin colloid fragmented ) and pleomorphic adenomas of the salivary gland ( myxoid background poor and present in droplets ) , a support on cs may prove useful .
as observed by the authors , lbc of bony lesions do not require support of cs .
tp preparations are superior to cps with regard to clear background , monolayer cell preparation and cell preservation .
it is easier and less time consuming to screen and interpret tp preparations because the cells are limited to smaller areas on clear backgrounds , with excellent cellular preservation .
however , tp preparations are more expensive than cp and require some experience for interpretation .
lbc is strongly advocated in the best interest of public health , by improving the quality of the sample and reducing the likelihood of false - negative cytology results .
 background : liquid - based cytology ( lbc ) is fast becoming a useful method in evaluating both gynecological and non - gynecological preparations , including fine needle aspiration ( fna ) cytology 
 . even distribution of cells , decreasing obscuring background elements like blood and mucus , well preserved nuclear and cytoplasmic details and rapid fixation helps in better visualization of cells.aim:this study was conducted to asses the diagnostic accuracy of liquid  based cytology versus conventional smears in fine needle aspiration samples.study design : in this prospective study , we had 110 cases , including 30 cases of breast , 40 of lymph node , 10 of salivary glands , 18 of thyroid and 12 of bone and soft tissue . in each case , two passes were performed . 
 the first pass was for conventional preparation ( cp ) and the second pass yielded material for thin - prep ( tp ) preparation . 
 both cp and tp smears were compared for cellularity , background blood and necrotic cell debris , cell architecture , informative background , presence of a monolayer of cells and nuclear and cytoplasmic details by a semiquantitative scoring system . 
 wilcoxon 's signed rank test on an spss program was used for statistical analysis.results:diagnostic accuracy was better in lbc smears compared with cp smears due to lack of background debris and better cell morphology , which was performed according to wilcoxon 's signed rank test , yielding a p - value of < 0.001 . 
 however , in some cases , because of a decrease in cell size , clustering and altered background in lbc , a support of cp was essential.conclusion:lbc performed on fna samples can be a simple and valuable technique . only in few selected cases , where background factor is an essential diagnostic clue , a combination of both cp and tp is necessary . 