| Abstract|| |
Oral squamous cell carcinoma is the most common cancer of the oral cavity. The survival rates for oral cancer patients will significantly be improved provided lesions are detected and treated at the infancy stage. Early diagnosis is therefore of paramount importance. Histopathological examination is considered as the gold standard in diagnosing oral lesions. Therefore, the selection for a biopsy site is highly significant. In this article, we present a current review of the colposcope and oral application of the colposcopy technique and its use as an adjunct in the early diagnosis of premalignant and malignant lesions of the oral mucosa. We stress upon the fact that colposcopy (direct oral microscopy) of oral mucosal lesions helps in selecting more representative sites for biopsy than routine clinical examination alone. Because of its precision, versatility, ease of use, and being a non-invasive technique, colposcopy might prove to be a useful step toward continuing to learn and improve the care for our patients.
Keywords: Biopsy, colposcope, squamous cell carcinoma
|How to cite this article:|
Pallagatti S, Sheikh S, Puri N, Gupta D, Singh B. Colposcopy: A new ray in the diagnosis of oral lesions. Indian J Dent Res 2011;22:810-5
Oral squamous cell carcinoma (OSCC) is the most common cancer of the oral cavity, accounting for more than 90% of all the oral cancers.  Each year, globally, there are 222,000 new cases of oral cancer diagnosed in men (5% of all cancers) and 90,000 new cases diagnosed in women (2% of all cancers).  The clinical diagnosis of squamous cell carcinomas of the oral cavity is not difficult when the lesion is obviously invasive or when the patient experiences pain, functional limitation, or regional lymphadenopathy.  Oral cancer is usually first diagnosed when it becomes symptomatic and by this stage approximately two-thirds of patients would already have developed advanced disease with regional metastasis.  This would further lead to a consequently diminished prognosis.
|How to cite this URL:|
Pallagatti S, Sheikh S, Puri N, Gupta D, Singh B. Colposcopy: A new ray in the diagnosis of oral lesions. Indian J Dent Res [serial online] 2011 [cited 2020 Feb 16];22:810-5. Available from: http://www.ijdr.in/text.asp?2011/22/6/810/94676
The early detection of premalignant lesions of the oral cavity allows for treatment that may be sufficiently early to prevent their progression to an invasive carcinoma  thus improving both the survival rate and the quality of life.
Clinical examination often leads to uncertain diagnosis, and thus the final diagnosis of dysplastic or premalignant lesions of the oral mucosa cannot be based solely on clinical findings.  With the aim of improving the efficiency of these diagnoses, various techniques have been developed to complement the clinical examination and to facilitate the identification of initial carcinomas. 
Toluidine blue staining is the most common technique used for the early detection of oral cancer in high-risk patients. But in contrast, studies have shown the risk of affinity of the stain with DNA and as high as 30% risk of false-positive staining attributed to enhance the staining of ulcerations and filiform papillae of the tongue.  Exfoliative cytology has a false-negative rate of approximately 30%.  Various other methods used for the early detection of precancerous lesions and conditions include oral brush biopsy, autofluorescence, acetic acid staining,  chemiluminescence,  veloscope, etc; however, none of the methods is accurate to establish a final diagnosis. Although flow cytometry is a useful guide to an imminent malignant change, it is far from being a simple chair-side investigation. This necessitates the role of a supplementary biopsy of the lesion for histopathologic examination to frame a definite diagnosis.
Apart from the fact of using various supplementary investigations, there is no reliable method applicable to the oral cavity that can replace a biopsy for a more definitive diagnosis of oral cancer. The histological assessment of a biopsy specimen is regarded as the most reliable criterion for a correct diagnosis and is considered as the gold standard. Dysplasia and carcinoma in situ herald invasive oral cancer, but carcinomas also occur in areas with no previous signs of dysplasia.  This may be caused by the rapid emergence of invasive cancer, but it is also possible that earlier biopsy specimens were taken from unrepresentative sites of the lesion or before morphologic changes could be detected.  Consequently, the specimen must be taken from the most representative area. Colposcopy was thought of to serve the purpose based on its use in gynecological practice.
Colposcopy is a well-known medical diagnostic procedure used to examine the tissues of the vagina, vulva, and cervix, carried out under illuminated light with a magnified view of the area of interest (i.e., direct microscopy). Many premalignant and malignant lesions have discernible characteristics which can be detected through this examination, usually done by an instrument known as "colposcope."
Colposcopy is the gold standard tool in gynecology for diagnosis of cervical abnormalities particularly after an abnormal Pap smear More Details. It provides an enlarged view of the areas, to visually distinguish the abnormal appearing tissues from the normal to get the best representing biopsy sites for further pathological examination. The main goal of colposcopy is to aid in the prevention of the premalignant lesions by early detection and treatment.
In this article, we present a current review of the colposcope and oral application of the colposcopy technique and its use as an adjunct in the early diagnosis of the premalignant and malignant lesions of the oral mucosa. We stress on the fact that direct oral microscopy of oral mucosal lesions seems to offer advantages in selecting more representative sites for biopsy than routine clinical examination alone.
| Colposcope|| |
Colposcopy is firmly established in gynecological practice worldwide. It is the study of cervical morphology using stereoscopic binocular magnification provided by the colposcope. A colposcope is used to identify visible clues suggestive of abnormal tissue.
The colposcope was invented in 1925 by Professor Hinselmann of Hamburg, Germany, specifically for the purpose of detecting early cervical cancer. Various modifications have been done till date and various models of the instrument are available now. The colposcope looks like a pair of binoculars and is mounted on a pedestal with a light source attached to it [Figure 1]. It functions as a lighted binocular microscope to magnify the view of the cervix, vagina, and vulvar surface and other similar tissues. Illumination is provided by a halogen lamp via a fibreoptic cable connected to a system of lenses. It can magnify the tissue from 4 to 40 folds. Low power (×2-6) may be used to obtain a general impression of the surface architecture. Medium (×8-15) and high (×15-25) powers are utilized to evaluate the deeper layers of the tissue. The higher powers are often necessary to identify certain vascular patterns that may indicate the presence of more advanced precancerous or cancerous lesions.
It provides three-dimensional images of the tissue surfaces examined. Portable video cameras can be attached to the colposcope and viewed on a television monitor screen. A digital colposcope allows not only the real-time viewing of the colposcopic image on the video screen, but also enables the computerized manipulation of stored images.
Various light filters are available to highlight different aspects of the surface of the tissue. The filters help the physician to examine tiny blood vessels in the mucosal areas as the blue or green filtered light can cause abnormal capillaries to become more obvious. Thus, the colposcope is fitted with a green or blue filter to facilitate the examination of vascular changes and color tone as unfiltered white or yellow light reduces the contrast between the terminal vessels and the surrounding tissue. The focal length of the microscope is 200 mm, providing an optimal working distance. The accuracy of colposcopy for the detection of mucosal changes is between 70% and 98%. ,
| Examination Procedure|| |
Colposcopic examination takes very less time and requires no anesthesia. It is generally a safe and painless procedure.
Acetic acid wash
Sankaranarayanan and colleagues investigated the detection of cervical cancer in India using 4% acetic acid and reported the sensitivity and specificity of 88% and 78%, respectively. Since the anatomy of and the types of cancer found in the oral cavity and cervix are comparable, acetic acid seems to be an appropriate clinical marker for the detection of oral cancer as well.  Three percent acetic acid is applied to the mucosa using cotton swabs for about 30 s. The acetic acid helps to coagulate mucus, which can then be easily removed, and hence washes away mucus and allows abnormal areas to be seen more easily with the colposcope. The acetic acid produces swelling of both squamous and columnar epithelium and reduces its transparency by producing a transient coagulation of nuclear proteins and perhaps by other mechanisms which are as yet unclear. The acetic acid does not affect the mature, glycogen-producing epithelium because the acid does not penetrate below the outer one-third of the epithelium. The cells in this region have very small nuclei and a very large amount of glycogen. Dysplastic cells are the ones which are most affected. They contain large nuclei with abnormally large amounts of chromatin.
The areas that stain white after the acetic acid wash are called acetowhite lesions. The acetic acid effect develops in about 40-60 s and then fades over a similar time scale, but reappears on the repeated application of acetic acid. The vascular patterns are clearly seen just as the acetowhitening begins to fade.
Chronic trauma and chemical and mechanical irritation, such as that by tobacco, have shown to be related to acetowhitening. Smoking predisposes the oral mucosa to acetowhite staining. In 1990, Kellokoski et al. demonstrated that the acetowhiteness of the oral mucosa was significantly more frequently in smokers, but the staining was not related with alcohol consumption, and histological and cytological findings. The age of the subject also influences acetic acid staining as aging produces degenerative changes which cause the epithelium to be less reactive to acetic acid. The acetowhiteness of the oral mucosa seems to be significantly associated with smoking and age but further studies are required to prove this connection.
Sometimes, however, normal areas can also stain white, but these areas have vague or faint borders. In contrast, significant abnormalities such as lichenoid reactions, lichen planus leukoplakia, and squamous cell carcinomas generally produce acetowhite areas with distinct and clear boundaries. However, acetic acid also causes tissue swelling, thereby reducing the transparency. Areas of the tissue which turn white after the application of acetic acid or have an abnormal vascular pattern are often considered for biopsy.
If after acetic acid application no lesions are visible, staining with a dilute iodine solution known as Lugol's solution or Schiller's solution is used for further examination of abnormalities. The normal squamous epithelium is rich in glycogen which will generally take up the iodine stain and turn brown in a uniform manner, whereas precancerous and cancerous lesions will not.
The acetic acid solution and iodine solution (Lugol's or Schiller's) are applied to the surface to improve the visualization of abnormal areas.
| Criteria for Vascular Changes|| |
In a recent study, Pazouki et al.  concluded that there was a close relation between vascularity and tumor progression in the oral mucosa. The vascular changes described in the colposcopic literature can be used as the criteria for selecting biopsy sites in the oral cavity. One of most frequently used and widely accepted index is Reid's index [Table 1].  Direct microscopy makes it possible to see what a healthy naked eye cannot see. Care can be administered more precisely with an enhanced appearance. Diverse blood vessel patterns can be observed on colposcopic examination which is best studied using a variety of magnifications and accentuating blue or green filters. Studies have reported the accuracy of colposcopy for the detection of mucosal changes is between 80% and 98%. These characteristics are extremely valuable for identifying the different diseased entities.
The normal squamous epithelium of the oral mucosa is pink and smooth which demonstrates fine, regular vessels. This normal vascularity can be altered in various inflammatory, benign, and malignant lesions and conditions. Colposcopic findings that suggest invasion are as follows: (1) abnormal vascular pattern, (2) irregular contour with a loss of the surface epithelium, and (3) color tone change.  Colposcopic-directed biopsies avoid false-negative results thus allowing treatment to be administered without delay.
Color tone changes
The color tone may change as a result of the increasing vascularity, surface epithelial necrosis, and in some cases, production of keratin. The color tone is a yellow-orange rather than the expected pink color of the intact squamous epithelium.
Margins and color
Following the application of 3-5% acetic acid to mucosal epithelium, the color, degree of whiteness obtained, rapidity, duration of acetowhitening and sharpness of the lesion borders are observed. High-grade lesions demonstrate a more persistent duller shade of white, whereas low-grade lesions are translucent or bright white and fade quickly. Low-grade lesions have feathery margins and irregular borders whereas high-grade lesions have straighter, sharper outlines and well-defined borders. A lesion with an internal border that is a lesion within a lesion is typically high grade.
| Vascular Pattern|| |
Normal oral mucosa
In the normal mucosa, two basic types of capillary networks can be seen with the colposcopy procedure: Network capillaries [Figure 2] and hairpin capillaries [Figure 3].
|Figure 2: Illustration of the blood vessel patterns seen during colposcopic examination. Network capillaries|
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|Figure 3: Illustration of the blood vessel patterns seen during colposcopic examination. Hairpin capillaries|
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The vascular patterns associated with abnormal epithelium include punctuation, mosaicism, and atypical vessels. ,
In areas of dysplasia and carcinoma in situ of the uterine cervix or oral mucosa, a specific vascular pattern, punctuation, is common [Figure 4], characterized by dilated, often twisted, irregular, hairpin-type vessels. These dilated capillaries terminating on the surface appear from the ends as a collection of dots and are thus referred to as punctuation [Figure 5].
|Figure 4: Illustration of the blood vessel patterns seen during colposcopic examination. Punctate vessel pattern|
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|Figure 5: Punctate vessel pattern seen in areas of dysplasia and carcinoma in situ of the oral mucosa|
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Another pattern of the vessels in dysplasia is called mosaic [Figure 6]. Terminal capillaries surrounding roughly circular or polygonal blocks of acetowhite epithelium crowded together are called mosaic because their appearance is similar to a mosaic tile. These vessels form a basket around the blocks of abnormal epithelium.
|Figure 6: Illustration of the blood vessel patterns seen during colposcopic examination. Mosaic vessel pattern|
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Like punctation vessels, true mosaic vessels are usually seen in sharply demarcated areas. Punctate and mosaic patterns are graded on the basis of vessel caliber, intercapillary distance, and the uniformity of these. Fine punctuation and mosaicism which are created by narrow vessels and uniform intercapillary distances typify low-grade lesions. A coarse pattern resulting from a wider and more variable vessel diameter and spacing indicates higher grade abnormalities. The mosaic tiles with central punctuation indicate carcinoma in situ.
Fracturing of previously intact mosaic and punctuate patterns with the production of predominantly waste thread like vessels is an earlycolposcopic warning sign of squamous microinvasion or cancer. Thus dilation and proliferation of the resulting punctate and mosaic patters increase with the degree of neoplastic change. When it is difficult to describe the pattern of the vessels, the term atypical vessels is used [Figure 7]. Atypical vessels are terminal vessels that are irregular in size and shape and coarse and such arrangement indicates neoplasia [Figure 8]. As the neoplastic growth process proceeds and the need for oxygen and nutrition increases, angiogenesis occurs as a result of tumor and local tissue production of VEGF, PDGF, EGF, and other cytokines, resulting in the proliferation of blood vessels and neovascularization. Atypical vessels may be looped, branched, or reticular. Sharp turns, dilations, and luminal narrowing also characterize these vessels. The surface epithelium may be lost in these areas leading to irregular surface contour and friability. Common to all these vascular patterns is irregular vessel dilatation and intercapillary distances greater than the normal distance of 50-200 μm. With the increasing degree of dysplasia, the distance increases so that the maximum distances may exceed 700 μm.
Irregular surface contour
Abnormal surface patterns are observed as the tumor growth proceeds. The surface epithelium ulcerates as the cells lose intercellular cohesiveness secondary to the loss of desmosomes. Irregular contour may also occur because of a papillary characteristic of the lesion.
After a complete examination, the colposcopist determines the areas with the highest degree of visible abnormality are determined and further subjected to biopsy and histopathological examination.
| Discussion|| |
Colposcopy offers precise early care with enhanced appearance. The need for a noninvasive technique for the early detection of cancers has long been recognized. The surface pattern, clarity of demarcation, color tone, and opacity can be more easily identified by direct oral microscopy than by routine clinical examination. This will aid in the earliest detection of premalignant lesions and conditions such as leukoplakia, lichen planus, lichenoid reaction, and various others.
In year 2000, a study was done in Sweden by Gynther et al. in 35 patients with various clinical diagnoses, such as leukoplakia, oral lichenoid lesions, or suspected malignancy. The most representative site according to colposcopic criteria was compared with the best site for biopsy according to clinical criteria. The study concluded that direct oral microscopy of mucosal lesions seems to offer advantages in selecting more representative sites for biopsy than routine clinical examination alone. 
It is not possible to determine the progression from dysplasia to carcinoma on the basis of the clinical findings. Similarly, such a progression of mucosal cannot be detected because areas of suspected mucosal change may contain foci of varying degrees of dysplasia, reversible or irreversible. Regular follow-up examinations are therefore essential for precancerous lesions, such as inhomogeneous leukoplakia. Hopefully, direct oral microscopy will be used to follow mucosal lesions and detect signs of progression because at present, this seems to be the only way to evaluate vascular changes in the oral mucosa.
Compared with staining with toluidine blue, the main advantage of using direct oral microscopy may be that follow-up is easily possible and the effect of treatment provided can be determined. Compared to toluidine blue and other methods, its accuracy is about 80-90%. The other methods have been reported to give a lot of false-positive and -negative results which can be misleading. ,,
| Conclusion|| |
Because of precision, versatility, ease of use and being a noninvasive technique, colposcopy can be used for early diagnosis of lesions and selecting an appropriate biopsy site. In screening programs aimed at detecting and eliminating precancerous and cancerous lesions and conditions, colposcopy plays an important adjunctive role with histology and cytology. Further studies to evaluate its accuracy and efficacy in detecting oral lesions and a comparative evaluation with other methods used are required which could be a step toward continuing to learn and improve the care we offer to our patients.
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Department of Oral Medicine and Radiology, MM College of Dental Sciences and Research, Mullana, Ambala, Haryana
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]