Value of Liquid Based Cytology Compared to Conventional Smear in Fine Needle Aspiration of Cytology - Essay Example

The value of liquid based cytology compared to conventional smear in fine needle aspiration of cytology INTRODUCTION Fine needle aspiration (FNA) isthe latest emerging diagnostic technique which has rapidly gained wide acceptance among the masses. Whether FNAC or Conventional smear, still remains an issue governed by controversies. Certain cytopathologists still prefer the conventional smear technique while others have moved onto adopt the FNAC. Various researches and countless studies have been conducted to deduce which one is better. Results have been diverse. FNAC proved better in certain areas, while in others CS proved superior, whereas other studies pronounced both the techniques equally effective. Also termed as Fine Needle Aspiration Cytology (FNAC), it is a simple, quick and inexpensive method used to diagnose superficial surface masses, and is especially useful in sampling the accessible head and neck masses in outpatient department (Pilotti et al 1993). Masses located within the region of the head and neck, including salivary gland and thyroid gland, cervical masses and nodules, and intraoral lesions can be readily diagnosed using this technique. It is the procedure of choice in outpatient departments, especially for the lesion of head and neck. Some of such studies have been considered here to comprehend the differences and efficacies of each of the two techniques SUMMARY: FNAC proves to be better than conventional smear in a number of ways. It is relatively safe since it is pretty much noninvasive when it comes to diagnosing malignancies, to which the only alternative before the advent of FNA was open excision biopsy. The most commonly encountered lesions in this area are lumps or swellings. The differential is important to rule out the malignancy, which is the most suspected diagnosis (Lee et al 1987, Skoog et al 2009). The technique is relatively easy to perform, fairly accurate and well tolerated by the patients. It is associated with low morbidity as it causes minimal suffering and carries next to no risk of complications. Its accuracy turns out to be the major reason for its preference over the conventional Pap smear. CRITICAL REVIEW: Numerous studies have been conducted in the area to analyze the advantages and pitfalls of both the techniques. The critical review below will outline various studies and help establish a view point about the two and reveal the superiority of FNAC. 1. Parfitt et al (2007) conducted a research to analyze the accuracy given by the two techniques. CS offers more accurate diagnosis more often. Accuracy offered by CS was 57% as compared to just 42% with that of thinprep. Thinprep has a higher unsatisfactory rate as well, i.e. 19% as compared to 9% of CS. The rate of errors seems to be similar with both techniques, i.e. about 4% while the indeterminate result rate of 35% is also similar with both the techniques. Morphologically, CS offers more diagnostic yield for highly cellular cases than TP, whereas for low cellular cases, diagnostic yield with both techniques was similar. TP proved better considering the artifacts, which are more frequent with CS. Crush is encountered 12% of cases using CS while with TP it is just 2%, similarly air drying is 13% versus 0% in TP and obscuring blood in CS is 27% versus 1% in TP. CS gives a larger cell size, while fragmentation and nuclear detail was better in TP. CS proved more specific for the diagnosis of pleomorphic adenoma, i.e. 83% versus 63% compared to TP. Stroma was more abundant and epithelial-stromal interface (ESI) was more frequent in CS (76% versus 38%). Conclusion: TP and CS are equally effective for the diagnosis of highly cellular cases. CS however appears to be better in overall diagnosis of pleomorphic adenoma. 2. A study by Zhang et al (2004), based upon 522 samples from different lesions including metastatic cancer, lymph node, thyroid and salivary gland were analyzed for comparison between ThinPrep and CS. The slides were analyzed to appreciate the differences in cell quality, overall cellularity, cell preservation, nuclear architecture and background. The cell quality of ThinPrep was found to be superior to CS in metastatic cancer analysis (51.0%, versus 14.9 %,), but inferior to CS in lymph node group (16.5% versus 58.2%). TP showed greater cellularity than CS in the set of metastatic cancer (32.2% versus 21.8%). TP showed better cell preservation and abnormal architecture than CS in metastasis cancer group (60.9% versus 9.4%). In the lymph node group, cell quality of TP slide was inferior to CS (16.5% versus 58.2%) with 27 of the 46 cases presenting tuberculosis. Cell quality of TP and CS slide turned out to be similar in the thyroid and salivary gland group i.e. 35.3%. In the setting of diagnosis of fibroadenoma, myoepithelial cells on the TP slide were decreased in number and, due to the increased papillary and flattened cells, the benign lesion proved easy to be diagnosed. Conclusion: In metastatic cancer group, cell quality of the TP is superior to CS, but they are similar in thyroid and salivary gland analysis. The difference of diagnosis criteria exists in tuberculosis, partly the reactive hyperplasia cases. 3. Rossi and Fadda (2008) conducted a research that proved overall superiority of FNAC in a number of ways: (1) simplification of the sampling technique; (2) decrease of the cellular artifacts, lowering the chances of misdiagnosis, and (3) applicability to additional investigations. However there are certain limitations, since FNAC does not prove to be excellent on certain grounds, on which CS seems to be a better option: (1) changes in the morphological picture of some lesions; (2) increase of the workload for the technical staff; and (3) cost increase. Conclusion: The only hardships encountered with TP relate to the sophisticated laboratory and skill, which can certainly be overcome. Thus, TP still is the better option to replace the CS as it offers a better morphology for diagnosis. 4. The vital role of Top of FormFine needle aspiration in diagnosis of Thyroiditis is depicted clearly by Kinni (2007). FNAC of thyroid is simple and cost-effective in initial screening of patients with thyroid lesions. Its diagnostic value is evident by its accuracy to diagnose a minimally enlarged thyroid (goiter) that may even be nonpalpable, in a symptomatic patient suspected of thyroid dysfunction. The detection of Thyroiditis along with the thyroid hormonal imbalance (Thyroid-stimulating hormone, T3 and T4) is detectable in early stages. Early detection of subclinical hypothyroidism, particularly in pregnant women is also remarkable. Conclusion: This study revealed further advantages of FNAC in the setting of Thyroid abnormalities. The implementation of this protocol of FNA thyroid further depends upon the geographic area, economy of the country and available infrastructure.Top of Form 5. Another research about thyroid FNAC, by Willems and Lowhagent (1981) pronounce thyroid FNAC as a low-cost, office procedure which even in children does not require regional anesthesia. In post-therapy follow-up of thyroid cancers, FNAC allows prompt detection of recurrence. The method is safe and free of side effects. The procedure can be repeated whenever necessary because all it requires is needling, which is readily accepted by the patients. The result can be obtained rapidly. The FNAC report helps make a decision whether the patient will benefit from non-surgical management, like those suffering from colloid goiter, thyroiditis and lymphoma, or to plan surgical intervention in papillary, medullary and anaplastic giant cell carcinomas. Conclusion: FNAC thus spares the patient from time-consuming and expensive investigations. Performed by an experienced cytopathologist, it is a reliable means of choosing patients for operation, thereby reducing the frequency of operations for benign lesions. 6. Turkish Journal of Pathology illustrates the comparison between the two techniques in a remarkable way. Türk patoloji dergisi (1985) assesses head and neck lesions on semi quantitative scoring system (Table 1). The cytological aspirates are scored from 0 to 3 as Bottom of Form nondiagnostic, benign, suspicious and malignant respectively. The sites of aspiration for the study were lymph nodes (n=27), soft tissue (n=20), thyroid (n=13) and salivary gland (n=11). Representative slides of CS and TP were compared for cellularity, obscuring background material (blood and necrotic debris), cell architecture, informative background (such as colloid, myxoid matrix, stromal fragments, lymphoglandular bodies etc.) and presence of monolayer cells in addition to nuclear and cytoplasmic details. No statistical difference was seen between the two groups with respect to the presence of monolayer cells, cell architecture, and nuclear details. Cellularity, informative background and cytoplasmic details were more substantial with CS. However, TP proved superior to CS considering the absence of blood and necrosis. In TP, there was a significant exclusion of the obscuring background including blood and necrosis. TP were also easier to infer because of the presence of cells in small areas, with clean backgrounds. The cells were more evenly distributed in the slides, with less overlapping, but informative background including myxoid matrix in salivary gland neoplasms and colloid in thyroid aspirates were less prominent in TP. Lymphoglandular bodies were also not seen in the background of TP. On the scale of 0 to 3, the ratio for CS over TP turns out to be 1, 37, 4, and 29 as compared to 6, 35, 7, and 23. Conclusion: The superiority of Thinprep is evident above, as it provides better specimen with less obscuring material, and a clean even background. Both of these certainly are the key points in considering the accuracy of diagnosis. 7. Hayama et al (2005) cited a recent study from Brazil, in which the liquid-based preparations resulted in higher specimen resolution as well as presented a better cytological morphology for pemphigus vulgaris, squamous cell carcinomas, HSV lesions and fungus infections. On microscopic analysis, the liquid based technique greatly improved the cytopathological features of HSV lesions with pronounced details of cytopathic effect (hyperchromatism, binucleation, multinucleated cells) indicating a viral infection. In autoimmune diseases, like pemphigus vulgaris, although both techniques were effective in making the diagnosis, the liquid-based preparations allowed better detection of cellular sheets showing loss of the intercellular cement (acantolysis). Conclusion: This study proves and appreciates broad spectrum implementation of FNAC on the broad scale in various settings to aid the diagnostic techniques. 8. Comparison between CS and Liquid based preparations in oral lesions was carried out by Hayama et al (2005). The study involved 44 patients. Top of Form Bottom of Form Top of Form On specimen analysis, the liquid-based cytology demonstrated a statistically significant, 41% overall improvement in smear thickness and 66% in cell distribution, and a reduction in cell overlapping and presence of blood. The cell morphology was better visualized in the liquid-based preparations. The liquid-based technique showed an overall improvement on sample preservation, specimen adequacy, visualization of cell morphology and reproducibility. Among the adequately cellular samples, the liquid-based preparations showed a statistically higher improvement in thinness (41%) and cell distribution (66%) as compared with those of conventional cytology. For the satisfactory but limited specimens, the liquid-based preparations showed reduced cell overlapping (thick smear), uneven cell distribution was comparatively reduced, and so was the presence of blood. No statistical difference was found in regard to leukocytes/ inflammation, microbiota, artifacts, or unsatisfactory results. The diagnostic accuracy turned out to be very high in both techniques while examining all 44 lesions, since both yielded adequate specimens. In 3 cases the conventional smear was hypocellular and therefore inadequate for analysis. The slides prepared by liquid-based cytology presented a thin and uniform distribution of cellular material, in addition to a clear background due to reductions in both cell overlapping and the presence of blood. Thus, with liquid-based the cellular morphology was clearer. In the analysis of the oral carcinoma lesions the liquid-based preparations also offered advantages over the conventional smears as they permitted for a better observation of cytological abnormalities and changes in the nuclear-cytoplasm ratio. Conclusion: This insight into cytopathologic techniques by Hayama et al (2005) provides a clear contrast among the two, i.e. conventional smear and ThinPrep. FNAC certainly proves better and more promising as it provides thin and uniform specimen for analysis. Its superiority for the diagnosis of oral carcinoma lesions is also evident. 9. The above cited study by Hayama et al (2005) also provides additional information about the comparative role of liquid based cytology and conventional smears in regard to immunocytochemical assay. The samples obtained by both techniques from patients of oral squamous cell carcinoma were tested for the viability of immunocytochemical assays. The immunocytochemical assay reactions using liquid-based preparation showed a positive reaction with AE1/AE3cytokeratin; with cells staining in red-brown pattern prove the malignancy, with visualization of malignant cells being very clear in a clear background. The use of ThinPrep technique in immunocytochemical assay proved beneficial as it significantly reduced the amount of antibody required, as well as the cost. Conclusion: The use of FNAC to rule out malignancy through immunocytochemical assay is it’s another remarkable milestone which has graded it better than conventional smear. 10. There are however certain points to be kept in mind with the use of ThinPrep. The artifacts introduced by ThinPrep technique are described by Micheal et al (2006). These artifacts should be recognized to avoid misdiagnosis. Bottom of Form On specimen analysis, the ThinPrep smears were reliably devoid of obfuscating elements, and the cells were finely preserved and evenly dispersed. However, there were some cytomorphologic alterations. The size of cell clusters is diminished; large forking sheets are split so there are more solitary cells, resulting in apparent lack of organization and a look of discohesion. Small cells such as lymphocytes incline to adhere together. All cells appeared generally smaller and sometimes spindled, the chromatin detail was attenuated, and nucleoli seemed more prominent. Intranuclear inclusions are hard to visualize. Background matrix was often altered in both quantity and quality. Extracellular particles, small mononuclear cells, red blood cells, and myoepithelial cells were markedly decreased in number. Conclusion: These cytomorphological variations are present and the pathologist should keep these artifacts in mind to avoid misinterpretation and circumvent flawed diagnoses. CONCLUSION: The aforementioned studies prove the superiority of ThinPrep over the conventional smear in all ways. To summarize them all, the main advantages are numbered below: 1. The simplicity of the technique, reduced time to perform and the reduction of expenses involved make it a treat for the cytopathologist as well as the patient. 2. Its diagnostic accuracy is the prime advantage. 3. The absence of obscuring elements like necrotic debris, crush, blood, air drying aid perfect diagnosis. This provides a clean background to appreciate the morphological and histochemical details. 4. The slides produced by ThinPrep are thin and have uniform distribution of the specimen with less overlapping. 5. FNAC is a technique that is now being used vastly. With its ever-increasing spectrum, it is helpful for analysis in the settings of viral, fungal, and autoimmune lesions. Detection of malignancies by immunocytochemical assay is another achievement.. 6. FNAC is remarkably advantageous over conventional smear in the setting of thyroid aspirates, where it detects abnormalities at an early stage and allows a cost-effective management of the condition. REFERENCES: 1. AL-KHAFAJI BM, & AFIFY AM. (2001). Salivary gland fine needle aspiration using the ThinPrep technique: diagnostic accuracy, cytologic artifacts and pitfalls. 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