BENIGN TUMORS OF EPITHELIAL

ORIGIN

Classification:• Squamous papilloma• Squamous acanthoma• Keratocanthoma• Oral nevi

SQUAMOUS PAPILLOMA• The oral squamous paillomas are seemed to be associated with papilloma virus, the one commonly incriminated as causative in skin warts• It is the fourth most common oral mucosal mass and is found in 4 of every 1000 individuals• The HPV types 6 and 11, are commonly associated with squamous paillomas, failed to be demonstrated in oral maligancies• Even though all HPV lesions are infective, the squamous papilloma appears to have an extremely low virulence and infectivity rate.

• The papilloma is an exophytic growth made up of numerous, small finger like projections, which results in roughened, verrucous, or ‘cauliflower ’ like surface.

• It is well circumscribed pedunculated tumor, may be sessile and is commonly pinkish in colour.

• Most common site is tongue, followed by buccal mucosa, lip, gingiva and palate, particularly area adjacent to uvula

• Resembles verucca vulgaris occuring on fingers, caused by HPV

• These are often seen in patients with verrucae on hands or fingers, and the oral lesions appear to arise through autoinoculation by finger sucking or fingernail biting

Clinical features:

Pink, papillary growth attached to the soft palate by a stalk

Pink, pedunclated and papillary lesion attached to the lingual frenum

White, exophytic growth with papillary projections exhibiting a cauliflower appearance

• The microscopic appearance of the papilloma is characterstic and consits of many long, thin, finger-like projections extending above the surface of mucosa• Projections are made up of a continous layer of stratified squamous epithelium and containing a thin, central connective tissue core•Some papillomas exhibit hyperkeratosis depending upon the location of lesion and amount of trauma or frictional irritation to which it has been subjected• Koilocytes may or may not be found• Chronic inflammatory cells may be variably noted in the connective tissue

Histologic Features:

Squamous papilloma

Treatment and prognosis • Treatment of the papilloma consists of excision,

including the base if the mucosa into which the pedicle or stalk inserts.• Recurrence is rare if tumor is properly excised.• Intraoral verruca vulgaris is also treated by

conservative surgical excision or curretage but liquid nitrogen cryotherapy and topical application of kerationlytic agents are also effective.

SQUAMOUS ACANTHOMA:• The squamous acanthoma is an uncommon lesion which

probably represents a reactive phenomenon of the epithelium rather than a true neoplasm. It bears no known epithelium rather than a true neoplasm.

• It bears no known relationship to the clear cell acanthoma, which occurs with considerable frequency on the skin and may also be found on the lips

• The squamous acanthoma has no distinctive clinical appearance by which it may be identified or even suspected and may occur at virtually any site on the oral mucosa

• The lesion is histologically distinctive and consists of a well demarcated elevated and umblicated epithelial proliferation with a markedly thickened layer of orthokeratin and underlying spinous layer of cells.

Squamous acanthoma

• It is a benign epithelial neoplasm which histologically resembles squamous cell carcinoma

• Etiology unknown, suggested to be viral, genetic, chemical carcinogens etc

• Trauma, HPV, genetic factors and immunocompromised status also have been implicated as etiologic factors.

KERATOACANTHOMA:

• Usually occurs on external surface which are sun exposed areas like lip, nose, cheek, zygoma etc.

• Seen in all age groups, but incidence increases with age• It occurs twice as frequently in men as in women and is

less common in darker skinned individuals• Lesions typically are soitary and benign as firm, round,

skin colored or reddish papules that rapidly progress to dome shaped nodules with smooth shiny suface

• Lesion appears as an elevated umbilicated or crateriform ulceration which is 1.5 to 2 cm in diameter

Clinical features:

Keratocanthoma

Keratocanthoma

• Initially appears as nodule, which ulcerates and becomes crater like ulcerated nodule, keratin is present within the ulcer

• It grows to its full size in 4-8 weeks, remains static, then in following 6-8 weeks, it expels the central keratin core and heals, hence called as self healing carcinoma, recurrence is rare.

Clinical Course:

• Hyperplastic squamous epithelium growing into underlying connective tissue

• Surface covered by thick layer of ortho & para Keratin with central plugging

• Occasional dysplastic features are seen in the epithelial cells• At the leading margin of tumour, islands of epithelium appear to be

invading connective tissue and it is almost impossible to differentiate it from Squamous cell Carcinoma

• Perineural invasion has also been reported, but does not have an adverse effect on biological nature of tumour

• Connective tissue is infiltrated with chronic inflammatory cells• At the margin of the lesion, the normal adjacent epithelium is elevated

towards the central portion of crater, then an abrupt change of normal epithelium occurs into Hyperplastic Acanthotic epithelium

• Hence, Inclusion of the adjacent border of specimen is must in the biopsy to reach a conclusion.

Histological Features:

Keratocanthoma

Treatment:• The lesion is usually treated by surgical excision• Residual scar may be present in some cases• Prognosis is excellent following excisional surgery.• Patient with history of keratocanthoma should be followed for the development of new primary skin cancers

ORAL NEVI• Categorized as hamartomas, developmental malformations,

the nevi are benign proliferation of nevus cells in either epithelium or connective tissue. Adults whites harbor this lesion rather commonly but intraoral lesions are much less common

• On the basis of histologic location of the nevus cells, cutaneous acquired nevi can be classified into three categories:

• Junctional nevus – when nevus are limited to the basal layer of the epithelium

• Compound nevus – nevus cells are in the epidermis and dermis

• Intradermal nevus – nests of nevus cells are entirely in the dermis

• The most common mucosal type is the intramucosal nevus,

which accounts for more than one half of all reported oral nevi. The common blue nevus is the second most common type found in the oral cavity.

Clinical features:• The intradermal nevus is one of the most common lesions

of the skin, most persons exhibiting several, often dozen, scattered over the body. The common mole may be a smooth flat lesion or may be elevated above the surface. This form of mole seldom occurs on the soles of the feet, the palms of the hands or the gentilia

• The junctional nevus may appear clinically similar to the intradermal nevus, the distiction being chiefly histologic. It is extremely important; however, that a distinction be drawn, since the prognosis of the two lesions is different.

• The compound nevus is a lesion composed of two elements and intradermal nevus and an overlying junctional nevus

• The blue nevus is a true mesodermal structure composed of dermal melanocytes which only rarely undergo malignant transformation. The majority of blue nevi are present at birth or appear in early childhood and persist unchanged throughout life

Blue Nevus

Oral Nevi

Histologic features:• The nevus cells are assumed to be derived from neural

crest• Nevus cells are large ovoid, rounded, or spindle –

shaped cells with pale cytoplasm; and may contain granules of melanin pigment.• They have ability to migrate from the basal cell layer

into underlying connective tissue• Intradermal nevus , the nevus cells are situated

within the connective tissue and seperated from the overlying epithelium by a well defined band of connective tissue. In intradermal nevus, nevus cells are not in contact with the surface epithelium

• Junctional nevus, this zone of demarcation is absent and the nevus cells contact and seem to blend into the surface epithelium, this overlying epithelium is usually thin and irregular and shows cells apparently crossing the junction and growing down into connective tissue• Compound nevus shows features of both the

junctional and intradermal nevus. Nests of nevus cellsare dropping off from the epidermis, while large nests of nevus cells are also in the dermis• The spindle cell and epithelioid cell nevus is

commonly composed of pleomorphic cells of three basic types ; spindle cells. Oval or epithelioid cells, and both mononuclear and multinicleated giant cells• The blue nevus is of two types: the common blue

nevus and the cellular blue nevus. In the common blue nevus, elongated melanocytes with long branching dendritic processes lie in bundles, usually oriented parallel to the epidermis, in the middle and lower third of the dermis.

Junctional Nevus

Compound Nevus

Intradermal Nevus

Treatment and prognos is : • Since the acquired pigmented nevus is of such common occurrence, it would obviously be impossible to attempt to eradicate all such lesions.• Surgical excision of all intraoral pigmented nevi is recommended as prophylactic measure because of the constant chronic irritation of the mucosa in nearly all intraoral sites occasioned by eating, tooth brushing etc

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