Update on special techniques in routine cytopathology

The role of tobacco as an etiological agent for oral cancer: Cytomorphometrical analysis of the buccal mucosa in tobacco users

BACKGROUND

Histopathological diagnosis of lesions arising from the intake of tobacco is based on subjective evaluation of morphological alterations within the lesional tissue. Oral exfoliative cytology is a non-invasive diagnostic technique for early detection of oral premalignant and malignant lesions. Morphometric techniques have been advocated as objective and reproducible methods of detecting changes before they are visible by routine microscopy and can facilitate differentiation of normal and abnormal epithelium. This study was conducted to assess the morphometric parameters (cell diameter, nuclear diameter and nuclear cytoplasmic ratio [N:C ratio]) in tobacco smokers and chewers and to evaluate the variations, if any.

MATERIALS AND METHODS

The study was conducted on cytological smears obtained from oral lesions of patients with habit of tobacco smoking (Group B) and tobacco chewing (Group C). Group A comprised of subjects free from oral lesions and not using tobacco in any form. Patients with both the habits were excluded. The smears were stained using Papanicoloaou staining method. For morphometric analysis, Microimage 3.0 image analysis software was employed. The statistical test employed was an analysis of variance and P < 0.05 was considered as significant.

RESULTS

The results of this study showed that the cellular diameter was progressively reduced and nuclear diameter progressively increased from Group A to Group B to Group C. The N:C ratio also showed a progressive increase from Group A to Group C.

CONCLUSION

The results confirmed that tobacco chewing and smoking influenced the cytomorphology of normal appearing buccal mucosa and the degree of these changes were found to be greater in chewers as compared to smokers.

Usefulness of oral cytopathology in the diagnosis of infectious diseases

In recent years, the incidence of oral opportunistic infections has increased, partly due to the widespread implementation of organ and bone marrow transplantation and the increase in the prevalence of human immunodeficiency virus (HIV) infection. Cytology can be used as a rapid, inexpensive and simple routine procedure in diagnosing infectious diseases of the mouth. Moreover, ancillary methods can be applied to cytological samples, increasing the specificity and sensitivity for the diagnosis of infectious diseases. This review describes the cytopathological features of the main viral, fungal, bacterial and parasitic infections of the mouth. Cytological techniques of specimen collection, identification of infectious agents by cytomorphological approaches and ancillary methods, and diagnostic pitfalls will be discussed.

Demonstration of CD44 gene expression in cells from fine needle aspirates of breast lesions by the polymerase chain reaction

Aim-To demonstrate the feasibility of studying specific gene expression in fine needle aspirates from clinical lesions. The reverse transcription/polymerase chain reaction (RT-PCR) technique was used to demonstrate CD44 gene expression in cells from diagnostic fine needle aspirates taken from patients attending the outpatient clinic for breast diseases.Methods-Polyadenylated RNA was extracted from the cells remaining in the syringe barrel after fine needle aspirate cytological diagnosis of 41 patients with breast lesions. Analysis of CD44 gene expression was performed by RT-PCR using primers flanking the site for insertion of the variant exons. The resulting products were separated on 1.2% agarose gels, transferred to nylon membranes using Southern blotting and hybridised with specific probes for standard (constitutive) and variant exons of this gene.Results-On hybridisation with the CD44 standard exon probe, the expected amplified product of approximately 482 base pairs was visualised in 22 of 41 samples examined. Further hybridisation with the "variant" exon probes (exons 7 (v2), 8 (v3), 9b (v4), 12 (v7), and 15 (v10)) on 12 of these samples showed the presence of large molecular variants in all of these samples. However, the expression pattern detected with the probes for exons 7 (v2), 8 (v3) and 9b (v4) differed among the patients.Conclusions-Expression of the standard and variant regions of the CD44 gene in cells remaining in the syringe after fine needle aspiration was demonstrated using RT-PCR. The 5' variant exon probes seemed to show different patterns of expression among the patients. Further studies are currently being conducted to determine whether there is any correlation between expression of the various components of this gene and cytological diagnosis. Using this method, it would be possible to study the expression of other candidate marker genes in breast cancer using fine needle aspirates.

Fine needle aspiration of lymph nodes

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Oral exfoliative cytology: review of methods of assessment

The use of oral exfoliative cytology in clinical practice declined due to the subjective nature of its interpretation and because there may be only a small number of abnormal cells identifiable in a smear. The more recent application of quantitative techniques, together with advances in immunocytochemistry, have refined the potential role of cytology, stimulating a reappraisal of its value in the diagnosis of oral cancer. This review considers the influence of the quantitative analysis of cytomorphology, DNA analysis and other tumour markers applied to oral exfoliative cytological samples. These studies indicate that oral cytology may provide an important adjunct in the assessment of the patient with a potentially cancerous oral lesion.

Diagnosis of pancreatic lesions using fine needle aspiration cytology: detection of K-ras point mutations using solid phase minisequencing

AIMS

To improve the diagnostic value of fine needle aspiration biopsy of pancreatic lesions using a simple mutation detection method based on the polymerase chain reaction (PCR).

METHODS

Fine needle aspirates from 21 suspected pancreatic lesions were analysed for K-ras codon 12 point mutations using solid phase minisequencing.

RESULTS

A point mutation in codon 12 of the K-ras gene was detected in 14 of 17 cases of pancreatic carcinoma. No false positive results were recorded. The concordance of the result with routine cytology was 78%. All patients diagnosed as having malignant disease on cytology also had a K-ras point mutation. Additional information on the presence of malignancy was obtained using molecular genetic analysis in two cases.

CONCLUSIONS

PCR based minisequencing is a promising method for the analysis of cytological material. K-ras point mutation analysis was modified to enable it to be carried out in a clinical laboratory. Advantages of the method include its simplicity and speed. Adequate sampling guidance is important but analysis can be performed even with small amounts of cellular material.