Pigmented Lesions

National university

Faculty of dentistry

Department of Oral Pathology

Semester 6

Dr. Mohand Hashem

TEL: 0904549067

Melanin-associated pigmented lesions

of the oral cavityBenign/hyperplastic

• Racial pigmentation

• Oral Melanotic Macule

• Lentigo

• Lentigo Simplex

• Ephelis – Ephelides

• Melasma

• Oral Melanoacanthoma

• Melanocytic nevi

Malignant

• melanoma

Racial pigmentation

• Dark-skinned individuals

• Diffuse bilateral

• Fungiform papillae distinct

• Gingiva, buccal mucosa, lips, palate tongue

• Innocent

• No treatment needed except for aesthetic purposes

Oral Melanotic Macule

• Relatively common lesion

• Increased melanin in the basal cell layer and

superficial connective tissue without melanocytic

activity

• Vermilion border of lower lip, anterior maxillary gingiva, buccal mucosa in blacks

• Intraoral lesions larger than labial

• 2F:M

• 5th decade

Histopathologic features:

• The oral melanotic macule is characterized by

an increase in melanin (and perhaps

melanocytes) in the basal and parabasal layers

of an otherwise normal stratified squamous

epithelium.

Lentigo

• Solar (actinic) lentigo

• Middle-aged and older patients

• UV light

• Face

• Between 0.5-1.0 cm

• Melanocytic hyperplasia

• Sharply circumscribed

• Single or multiple

• No malignant transformation potential

Histopathologic features

• Rete ridges are elongated and club shaped in

actinic lentigines, with thinning of the epithelium

above the connective tissue papillae.

• The ridges sometimes seem to coalesce with one

another. Within each rete ridge, melanin-laden

basilar cells are intermingled with excessive

numbers of heavily pigmented melanocytes.

Lentigo Simplex

• Melanocytic hyperplasia

• Any skin surface including skin not exposed to sunlight

• Color intensity does not relate to sun exposure

• Precursor to melanocytic nevi

• Small, uniform, tan to brown or black less than 5mm.

• Solitary or multiple

• Multiple are seen with rare syndromes

• Lentiginosis profusa, Peutz-Jeghers, LEOPARD, xeroderma

pigmentosum, etc

• Some lesions regress

• No malignant transformation potential

Histopathologic features:

• Lentigo simplex shows an increased number of benign melanocytes within the basal layer of the epidermis, and these often are clustered at the tips of the reteridges.

• Abundant melanin is distributed among the melanocytes and basal keratinocytes, as well as within the papillary dermis in association with melanophages (melanin incontinence).

Ephelis – Ephelides

• Fair-haired individuals

• Genetic predilection

• Melanocortin-1-receptor gene

• 1st decade; become less prominent in adults

• More pronounced after sun exposure

• Small, uniform color, not as dark as lentigo

simplex

Histopathologic features

• The ephelis is composed of stratified squamousepithelium

• Abundant melanin deposition in the basal cell layer.

• Despite the increased melanin, the number of melanocytes is normal or may be some what reduced.

• In contrast to lentigo simplex, there is no elongation of rete ridges.

Melasma

• Symmetric diffuse hyperpigmentation of sun

exposed skin

• Usually in pregnancy – very rare in men

• Estrogen and progesterone play a role

• Face

Histopathologic features

• Melasma is characterized by increased melanin

deposition within an otherwise unremarkable

epidermis.

• Pigment also may be seen within numerous

melanophages in the dermis.

Oral Melanoacanthoma

• Benign, uncommon, acquired

• Almost exclusively in blacks

• Buccal mucosa

• Fast increase in size

• Frequent spontaneous resolution

Histopathologic features

• The oral melanoacanthoma is characterized by numerous benign dendritic melanocytes (cells that are normally confined to the basal cell layer) scattered throughout the lesional epithelium

• Basal layer melanocytes are also present in increased numbers.

• Spongiosis and mild acanthosis are typically noted.

• In addition, eosinophils and a mild to moderate chronic inflammatory cell infiltrate are usually seen within the underlying connective tissue.

Nevi

• The generic term nevus refers to

malformations of the skin (and mucosa) that

are congenital or developmental in nature.

• Nevi may arise from the surface epithelium or

any of a variety of underlying connective

tissues.

Nevi

Types of Developmental Nevi

• Epidermal nevus

• Nevus sebaceus

• Nevus flammeus

• Basal cell nevus (nevoid basal cell carcinoma))

• White sponge nevus

Oral Melanocytic Nevi

• Nevus cell

• Palate

• Aquired, rarely congenital

• Macular Juctional

• Papular Compound or intramucosal

• Occasionally decrease in pigmentation

• Blue nevus

Acquired melanocytic nevus

(nevocellular nevus; mole)

• The most commonly recognized nevus is the

acquired melanocytic nevus, or common mole

• The acquired melanocytic nevus represents a

benign, localized proliferation of cells from the

neural crest, often called nevus cells.

• Many acquired melanocytic nevi will involute

and disappear

• Intraoral melanocytic nevi are distinctly

uncommon.

• Most arise on the palate, mucobuccal fold, or

gingiva, although any oral mucosal site may be

affected

Clinical features:

• Acquired melanocytic nevi begin to develop on the skin during childhood, and most cutaneouslesions are present before 35 years of age.

• They occur in both men and women, although women usually have a few more than men.

• Whites have more nevi than Asians or blacks.

• Most lesions are distributed above the waist

• The head and neck region is a common site of involvement.

• Acquired melanocytic nevi evolve through

several clinical stages, which tend to correlate

with specific histopathologic features.

• Ulceration is not a feature unless traumatizes.

Junctional nevus:

• The earliest presentation

• Sharply demarcated, brown or black macule

• Less than 6 mm in diameter.

Compound nevus:

• Nevus cells proliferate over a period of years

to produce a slightly elevated, soft papule with

a relatively smooth surface

• The degree of pigmentation becomes less;

most lesions appear brown or tan.

Intradermal nevus:

• As time passes, the nevus gradually loses its

pigmentation,

• the surface may become some what

papillomatous, and hairs may be seen growing

from the center

Histopathologic features:

• The acquired melanocytic nevus is characterized by a benign, unencapsulatedproliferation of small, ovoid cells (nevus cells).

• The lesional cells have small uniform nuclei and a moderate amount of eosinophiliccytoplasm,with indistinct cell boundaries.

• These cells demonstrate a variable capacity to produce melanin

• Melanocytic nevi are classified histopathologicallyaccording to their stage of development

• Junctional nevus:nevus cells are found

only along the basal cell layer of the epithelium.

• Compound nevus:cells begin to drop off into the underlying dermis or lamina propria.

• Intradermal (intramucosal) nevus:nevus cells are no longer found within the epithelium but are found only within the underlying connective tissue.

• Most intraoral melanocytic nevi are classified microscopically as intramucosal nevi.

Treatment and prognosis:

• No treatment is indicated for a cutaneous

melanocytic nevus unless it is cosmetically

unacceptable, is chronically irritated by

clothing, or shows clinical evidence of a

change in size or color.

• At least some skin melanomas arise from

longstanding or irritated nevi of the skin.

Variants of melanocytic nevus

Congenital melanocytic nevus:

• Affect new born

• divided into two types:

– Small (<20 cm in diameter)

– Large (>20 cm in diameter).

• 15% of congenital nevi are found in the head and

neck area, although intraoral involvement is quite

rare.

Clinical features:

• The small congenital melanocytic nevus may be similar in appearance to an acquired melanocytic nevus, but it is frequently larger in diameter.

• The large congenital lesion classically appears as a brown to black plaque, usually with a rough surface or multiple nodular areas.

• Clinical appearance often changes with time.

• Early lesions are flat and light tan, becoming elevated, rougher, and darker with age.

• A common feature is the presence of hypertrichosis which may become more prominent with age (giant hairy nevus).

• Patients with multiple large congenital nevi

also are at risk for developing neurocutaneous

melanosis, a rare congenital syndrome in

which patients may develop melanotic

neoplasms of the central nervous system

(CNS), including meningeal melanosis or

melanoma

Histopathologic features:

• The histopathologic appearance of the

congenital melanocytic nevus is similar to that

of the acquired melanocytic nevus, and some

small congenital nevi cannot be distinguished

microscopically from the acquired nevus.

Treatment and prognosis

• Many congenital melanocytic nevi are excised for aesthetic purposes.

• In addition, 3% to 15% of large congenital nevi may undergo malignant transformation into melanoma.

• Therefore, whenever feasible, these lesions should be removed completely by conservative surgical excision.

• Close follow-up is required for lesions not removed.

Variants of melanocytic nevous

Halo nevus:

• Is a melanocytic nevus with a pale hypopigmented border or “halo” of the surrounding epithelium.

• Result of nevus cell destruction by the immune system.

• Immune cells also attack the melanocytesadjacent to the nevus.

• The cause of the immune attack is unknown,butregression of the nevus usually results.

Clinical features

• An isolated phenomenon

• Associated with a preexisting acquired melanocytic nevus.

• Skin of the trunk during

• Second decade of life.

• A central pigmented papule or macule, surrounded by a uniform, 2- to 3-mm or more zone of hypopigmentation

Histopathologic features:

• Histopathologically, the halo nevus differs

from the routine acquired melanocytic nevus

only in the presence of an intense chronic

inflammatory cell infiltrate, which surrounds

and infiltrates the nevus cell population.

Treatment and prognosis

• Usually, treatment is not required for halo

nevus because it eventually will regress

entirely.

Spitz nevus (benign juvenile melanoma;

spindle and epithelioid cell nevus)

• An uncommon type of melanocytic nevus

• shares many histopathologic features with

melanoma.

• It was, in fact, first described as a juvenile

melanoma.

• Benign biologic behavior

Clinical features:

• skin of the extremities or the face during childhood.

• solitary, dome-shaped, pink to reddish- brown papule,

• smaller than 6 mm in greatest diameter.

• The young age at presentation and the relatively small size of the Spitz nevus are useful features to help distinguish it from melanoma.

Histopathologic features

• The Spitz nevus has the overall microscopic

architecture of a compound nevus

• showing a zonal differentiation from the

superficial to deep aspects of the lesion and

good symmetry.

Treatment and prognosis:

• Conservative surgical excision is the treatment

of choice for a Spitz nevus.

• There is little chance of recurrence after the

nevus is removed.

• Blue nevus (dermal melanocytoma,

(Jadassohn-tièche nevus)

• Blue nevus is an uncommon, benign

proliferation of dermal melanocytes, usually

deep within subepithelial connective tissue.

Two major types of blue nevus:

– Common blue nevus

– Cellular blue nevus.

Common blue nevus:

• Dorsa of the hands and feet, the scalp, and the

face.

• Mucosal lesions may involve the oral mucosa,

conjunctiva, and rarely sinonasal mucosa.

• Oral lesions are found almost always on the

palate.

• Children and young adults.

• Female predilection is seen.

• Macular or dome-shaped, blue or blue-black

lesion smaller than 1 cm in diameter

Cellular blue nevus:

• Much less common

• Second to fourth decades of life, but it may be congenital.

• 50% arise in the sacrococcygeal or buttock region,

• Cutaneous or mucosal surfaces may involve.

• Slow-growing, blue-black papule or nodule that sometimes attains a size of 2 cm or more.

• Occasional lesions remain macular.

Histopathologic features

• Common blue nevus consists of a collection of elongated, slender melanocytes with branching dendritic extensions and numerous melanin globules.

• Cells are located deep within the dermis or lamina propria

• The cellular blue nevus appears as a well-circumscribed, highly cellular aggregation of plump, melanin-producing spindle cells within the dermis or submucosa.

• Treatment and prognosis:

• If clinically indicated, conservative surgical

excision is the treatment of choice for the blue

nevus of the skin.

• Recurrence is minimal with this treatment.

Malignant transformation to melanoma is rare

but has been reported.

MALIGNANT MELANOMA

MALIGNANT MELANOMA

• Melanomas consist of neoplastic melanocytes

both within the epithelium and invading deeper

tissues.

Clinical features:

• Peak incidence between 40 and 60 years.

• Usually appear as black or brown patches.

• Amelanotic melanomas.

• They are macular or nodular and may ulcerate.

• The palate is most frequent site .

• Are typically firm and rubbery but

asymptomatic at first.

• melanomas may remain unnoticed until they

cause soreness, bleeding, or a neck mass,

unless noticed by chance

Histopathological features:

• consist of neoplastic melanocytes often

surrounded by clear halos, within the

epithelium and invading deeper tissues .

• Neoplastic melanocytes are round to spindle-

shaped and typically speckled or intensely

pigmented with melanin .

Treatment and prognosis:

• radical excision and usually chemotherapy or

radiotherapy or both.

• prognosis of intraoral melanomas is poor as

they are frequently unrecognised until there are

symptoms or involvement of lymph nodes .

• The median survival for mucosal melanomas

was less than 2 year