| Abstract|| |
Oral lesions indicative of biopsy represent unique presentation either in the form of proliferations/ulcerations of the squamous lining epithelium. These lesions have similar appearance clinically and histopathologically hence are excised for microscopic evaluation to rule out early or hidden malignancy. Verrucous mucosal lesions clinically present a diagnostic dilemma, which makes histopathological examination a significant one in the differentiation of the lesion to ascertain the nature. This short communication aims to discuss the different histological characterization of oral verrucous mucosal lesions.
Keywords: Papillary squamous cell carcinoma, papilloma, verrucous carcinoma, verrucous lesions
|How to cite this article:|
Swetha P, Supriya NA, Kumar GN. Characterization of different verrucous mucosal lesions. Indian J Dent Res 2013;24:642-4
Verrucous lesion presents as cauliflower-like, slowly growing lesion, which may be single, multiple or diffuse involving the broad areas of oral mucosal surface with either sessile or pedunculated base. Depending upon the degree of keratinization, color may appear pink or white. The lesions may be termed as "Papillary" or "Verrucous," wherein "papillary" implies nipple-like surface projections and "Verrucous" means a roughened surface, which is usually a wart or wart-like. Histopathology remains to be a gold standard in diagnosing this diverse group of verrucous lesions.
| Papilloma|| |
Oral papilloma is a soft-tissue lesion of the oral epithelium, which appears solitary, soft and pedunculated with numerous finger-like projections. Human papillomavirus (HPV) 6 and 11 viruses cause it, which is not associated with precancer or malignancy as it is less virulent and infective. HPV belongs to diverse group of viruses that manifest affinity to the squamous epithelium of the skin and mucous membranes. HPV altered epithelial cells, i.e. Koilocytes, which affects the intermediate layers and extends to the surface of the epithelium.  Clinical differential diagnoses includes verruca vulgaris, verruciform xanthoma and condyloma accuminatum.
Histologically, papilloma exhibits typical narrow stalks with numerous blunt and pointed finger-like projections. Similar histopathology is observed in [Figure 1] verruca vulgaris, but can be differentiated as the later shows its long rete ridges, which tend to approach one another toward the center of the lesion thereby producing a "cupping effect." In addition, a prominent granular layer (hypergranulosis) with coarse, clumped keratohyaline granules are also seen. 
|Figure 1: Photomicrograph of papilloma showing narrow stalks with numerous blunt and pointed finger-like projections (H and E, ×4)|
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Verruciform xanthoma shows the presence of typical "xanthoma cells" (foamy histiocytes) within the connective tissue papillae. The condyloma accuminatum shows broad base with blunt surface projections clinically and histopathologically, it is characterized by benign proliferation of acanthotic stratified squamous epithelium and minimum surface keratinization.
| Proliferative verrucous leukoplakia|| |
Hansen et al. first introduced this entity in 1985; as a unique leukoplakia, which is exophytic, progressively expanding lesion with a high risk of malignant transformation showing female predilection (F:M = 4:1).  Initially, it presents as hyperkeratotic lesion, which later spreads to adjacent sites and become "proliferative" or multifocal. Because of its aggressive nature and progressive growth, it has high chances of recurrence.
Cerero-lapiedra et al. (2010)  proposed major and minor diagnostic criteria for PVL, which was later simplified into four criteria by Carrard et al. as follows:
- Leukoplakia presenting verrucous or wart like areas involving more than two oral subsites
- Minimum size of all involved site should be at least 3 cm
- History of lesion for minimum 5 years characterized by spreading and enlarging along with recurrences in previously treated area
- At least one biopsy to rule out the presence of verrucous hyperplasia/carcinoma or SCC.
Histopathologically, PVL exhibits exophytic verruciform growth pattern with bulbous rete hyperplasia showing dysplasia in later stages [Figure 2]. Verrucous hyperplasia shows hyperplasia of squamous epithelium. It is considered by Hansen et al. to be a part of developmental spectrum of PVL [Figure 3]. Verrucous carcinoma does not fulfill the clinical criteria of PVL and does not show dysplasia on histopathology as that of PVL.
|Figure 2: Photomicrograph of proliferative verrucous leukoplakia showing broad rete processes with a downward invasive growth pattern (H and E, ×20)|
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|Figure 3: Photomicrograph of verrucous hyperplasia showing papillary or pointed surface projections (H and E, ×4)|
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| Verruca vulgaris|| |
Verruca vulgaris is often associated with HPV subtypes 2, 4 and 40 viruses, predominantly affecting children. It is a contagious lesion common on the skin when compared to the oral mucosa. Clinically, it presents as a hard rough surfaced papillomatous growth, which may be solitary or multiple in numbers.
Histopathologically, it shows papillary growth with long rete ridges producing "cupping effect" in the center of the lesion, hypergranulosis with coarse keratohyaline granules and koilocytes [Figure 4].
|Figure 4: Photomicrograph of verruca vulgaris showing exophytic, papillomatous growth with long rete ridges (H and E, ×4)|
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| Verrucous carcinoma|| |
The lesion present as large, exophytic, soft, fungating, slow growing neoplasm with pebbly mamillated surface affecting mainly the site where the tobacco is placed habitually, as tobacco chewing is a significant etiological factor for the development of verrucous carcinoma.
Verrucous carcinoma often tends to involve and destroy structures such as mandible on a broad front causing erosions with sharp margins, rather infiltrating the marrow spaces.  Verrucous carcinoma is locally aggressive with a low propensity for regional and distant metastasis. Usually, the enlarged lymph nodes at presentation are often reactive to a secondary infection or inflammation rather than true metastasis.
Histopathologically, tumor cells showing acidophilic, ample cytoplasm, minimum nuclear atypia, individual cell keratinization, koilocytosis, basal cell mild atypia and squamous pearl formation  [Figure 5] are the features that make verrucous carcinoma to be differentiated from verrucous hyperplasia, PVL and verruca vulgaris. However, it is suggested that verrucous carcinoma at a certain period may show dysplastic features in the entire epithelium and finally may progress into invasive squamous cell carcinoma (SCC).
|Figure 5: Photomicrograph of verrucous carcinoma showing enlarged bulb like acanthotic invaginations - giving it a "pushing margin" appearance (H and E, ×2)|
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| Papillary SCC|| |
Landman in 1990 coined the term "papillary SCC."  SCC are known to be associated with poor dental hygiene, ill-fitting dentures, low socio-economic status, tobacco chewing, snuff, alcohol use and smoking. Unlike papillomas, histologically, this lesion shows malignant squamous epithelium of varied thickness with finger like projections supported by fibrovascular areas.
This malignant squamous epithelium consists of immature basal cells with prominent cellular and nuclear pleomorphism [Figure 6], with a tendency to breach through the basement membrane. The tumor cells also shows abundant eosinophilic cytoplasm with large hyperchromatic nuclei, increased nuclear cytoplasm ratio, individual cell keratinization and a round focus of concentrically layered keratinized cells suggestive of keratin pearls.
|Figure 6: Photomicrograph of papillary squamous cell carcinoma showing malignant squamous epithelium of varied thickness with finger-like projections (H and E, ×4)|
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| Conclusion|| |
Oral verrucous lesions present a diagnostic dilemma to oral pathologists because of its similar characteristic features. Hence, proper understanding of histopathology of various types of lesions is required to arrive at a correct diagnosis. This article highlights the histopathological appearances of such lesions, thereby providing an aid for correct diagnosis and management.
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Department of Oral Pathology, Vishnu Dental College and Hospital, Bhimavaram, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]