THE VALIDITY OF CYTOLOGICAL EXAMINATION IN DIFFERENTIATION BETWEEN LEUKOPLAKIA AND LICHEN PLANUS

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         Ridha N.Alkizwini *** B.D.S.,H.D.D.

        Specialist oral and dental surgeon

        Email:  ridhadent@yahoo.com                                                                                

***Ministry of Health

   Missan Health Centre Amarrah Iraq       

SUMMARY                                                                      

Eight cases which appeared as white lesion in the oral cavity were included in this investigation. The cases were examined clinically, histological and cytological. The results of the diagnostic measures were matched for each case and analyzed. Cytological examination of smears taken from the above mentioned lesions may be of great help in preoperative diagnosis.

INTRODUCTION

The World Health Organization defined leukoplakia as a clinical white patch or plaque on the oral mucosa which will not rub off and which cannot be characterized clinically or histologically as any other specific disease. This rather negative definition highlights the fact that the diagnosis of leukoplakia is done by exclusion, probably gathering a group of heterogeneous lesions (e.g. lichen planus candidosis, lupus erythematosus etc.)

Moreover, leukoplakia is considered as a serious condition because some of the lesions may show signs of dysplasia or even malignant changes. 3 - 6 % of leukoplakias have been reported to undergo malignant transformation. However, a high percentage of leukoplakia may appear as simple hyperkeratotic lesions microscopically. No definite correlation between the clinical appearance of leukoplakia and the occurrence of epithelial dysplasia was established. Hence, proper management requires the differentiation of potentially dangerous   leukoplakia from other mucosal white lesions

Lichen planus on the other hand is also a white lesion that may resemble leukoplakia clinically in some cases. This resemblance makes clinical diagnosis rather difficult.

Typical cases of oral lichen planus and those associated with skin lesions are easy to diagnose clinically without the need of histological examination in most cases. A typical lichen planus, especially the plaque type are frequently misdiagnosed as leukoplakia and in such cases microscopic examination becomes necessary.

Leukoplakia has often been confused with oral lichen planus. The two conditions may even co-exist. Many authors have noted that leukoplakia and lichen planus can have similar clinical characteristics. Histological confirmation for cases where a clinical diagnosis is uncertain is strongly recommended.

The aim of the present investigation is to test a simple clinical method by which diagnosis can be confirmed in cases of leukoplakia and non-typical lichen planus which resemble leukoplakia clinically. By this method pre-operative diagnosis may become possible.

MATERIAL AND METHODS

1. Samples: A total of 8 patients (2 F & 6 M) attended the oral surgery Dept. Dental College University of Baghdad, complaining of oral white lesion. Thorough and accurate medical histories were recorded from each patient. A careful clinical examination of the lesions was performed.

2. Cytological smear: The cytological smears were prepared by the following method. The area to be examined was thoroughly irrigated with normal saline to remove food debris followed by gentle scraping of the lesion with a moistened wooden spatula. The scraping included the lesion proper, whereas the surrounding uninvolved mucosa was avoided.

The swabs were instantly spreaded on a clean, dry glass slide and then rapidly fixed in 95 % ethyl alcohol. The smears were stained by papanicoluou method and examined by the cytologist.

3. Biopsy: Incisional biopsy specimens were taken from all patients and fixed in 10% normal buffered formalin. These were examined by the pathologist.

All smears and biopsy specimens were labeled in such a way that they could be matched easily after collection of the results from both the pathologist and cytologist.

RESULTS

The results of this study (Table 1) showed that five cases were diagnosed as lichen planus histologically. In the cytological description of those cases superficial anucleated cells together with inflammatory cells were seen in the smear. On the other hand, two cases were diagnosed clinically and histologically as leukoplakia and their cytological smear showed squamous cells of varying degree of keratinization or dyskeratosis.

In one case, cytological and histological examination revealed a squamous cell carcinoma whereas clinically it was diagnosed as leukoplakia.

DISCUSSION

Leukoplakia and lichen planus raise occasional problems in their diagnosis when they present similar clinical characteristics. It may be difficult to differentiate leukoplakia from the plaque type of oral lichen planus. Histological confirmation is strongly recommended whenever clinical diagnosis is uncertain.

In the present study preoperative cytological examination is carried out in cases of leukoplakia and lichen planus in an attempt to find out a method of clinical differentiation. Since known lesion of lichen planus do not need surgical treatment or even biopsy removal. However, controversy concerning the value of cytological examination of keratotic lesions exists among various investigators. Some believe that the superficial keratinized layer impedes the emergence of deeper dyskeratotic cells. By contrast, others found that keratinization caused no difficulties .Others suggested removal of the keratin layer by instruments prior to cytological evaluation of hyperkeratotic leukoplakia. The results of this investigation showed three cases were diagnosed clinically and histologically as lichen planus. In the cytological description of these cases anucleated cells and inflammatory cells were seen in the smears. On the other hand in two cases clinical and histological diagnosis of leukoplakia was given. The cytological description of these two cases was the presence of squamous cells with varying degrees of kerationazation or dyskeratosis. Another two cases diagnosis clinically is leukoplakia whereas histological examination showed that they are lichen planus. Careful examination of smears from these two cases was similar to those of typical lichen planus.

 In only one case where clinical diagnosis of leukoplakia was given whereas both histological and cytological reports were that of well differentiated squamous cell carcinoma.

From the results of the present investigation it is obvious that one can speculate from the cytological description the nature of the lesion dealt with. However, cytological examination is never a substitute for a proper biopsy in case of clinically suspected malignancy