This document discusses benign epithelial tumors including squamous papilloma, squamous acanthoma, and keratocanthoma. It provides details on their classification, clinical features, histology, treatment and prognosis. Squamous papilloma is associated with HPV viruses and presents as a pink, papillary growth. Squamous acanthoma is a reactive lesion with thickened orthokeratin. Keratocanthoma appears as a crateriform nodule that heals within months. The document also covers oral nevi, noting their histologic subtypes and benign nature.

1. BENIGN TUMORS
OF EPITHELIAL
ORIGIN

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

3. 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.

4. • 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:

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

6. Pink, pedunclated and papillary lesion attached to the
lingual frenum

7. White, exophytic growth with papillary projections
exhibiting a cauliflower appearance

8. • 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:

9. Squamous papilloma

10. 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.

11. 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.

12. Squamous acanthoma

13. • 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:

14. • 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:

15. Keratocanthoma

16. Keratocanthoma

17. • 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:

18. • 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:

19. Keratocanthoma

20. Treatme
nt:• 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

21. 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.

22. 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

23. Blue Nevus

24. Oral Nevi

25. 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

26. •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.

27. Junctional Nevus

28. Compound Nevus

29. Intradermal Nevus

30. 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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