5- Dermatological Causes of White Patches (1) (1)

7/28/2019 5- Dermatological Causes of White Patches (1) (1)

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Dermatological causes of white patches

Lichen planus: Lichen = primitive plants composed of symbiotic algae and fungi Lichen planus = dry lichen-like appearance of affected skin It is the commonest dermatological disease that may result in oral white

lesions

It is a chronic mucocutaneous disease that involves skin and mucousmembranes

Clinical features: Skin lesions:

o Site: any area in the skin may be involved but the commonest siteis the flexer surface of the wrist

o Fingernails may be involved mostly with vertical ridging in 10%of the cases

o Scalp might be affected in females leading to alopeciao Clinical appearance:

- Purple, pruritic, papules (PPP) with white streaks onthe surface Wickhams striae which are

characteristic of this condition

- Papule = circumscribed solid elevation of skin with novisible fluid

- Papules show variable patterns (discrete, linear,annular, bullous)

- Lesions may also present as widespread rash (in whichskin gets warm, swollen, and maybe painful)

o Lesions develop slowly and 85% of them resolve in almost 18 months, however lesions mayrecur in some patients

** When lesions go they leave a pigmented scar behind that take considerable time to resolve

Oral lesions:o In contrast to skin lesions, oral lesions pursue a much more chronic course, sometimes

extending over many years (average duration 4.5 years)

o May occuralone or in combination with skin lesions


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o Site: lesions mostly affect buccal mucosa(90%), but may also affect the tongue, gingiva,palate, and lips. The floor of the mouth involvement is relatively uncommon

o Lesions are often bilateral and show wide spectrum of presentationso Clinical appearance:

- Non-erosive lesions: Reticular, annular, papular, plaque-like

** Reticular lesions have white streaks arranged in lace-like pattern

** Plaque-like lesions are white patches resembling leukoplakia clinically

** Papular lesions are small white papules that may coalesce

** Bullous lesions are subepithelial bullae

They are usually asymptomatic They may show hyperkeratosis with NO atrophy & NO ulceration

- Erosive/atrophic lesions:** Erosive lesions are extensive areas of shallow ulceration

** Atrophic lesions are diffuse red lesions resembling Erythroplakia

Erosion and atrophy are usually present together and lesions have a red glazedappearance with areas ofsuperficial ulceration which may take several weeks to heal

Occasionally, ulcers are preceded by bullae (bullous type) that then rupture Lesions are often associated with typical areas of non-erosive lichen planus They are usually symptomatic Pain and discomfort may be severe (especially when eating spicy/acidic foods)

- Gingival lesions: Lichen planus involving the gingiva often presents as a desquamative gingivitis

Reticular Annular Papular Plaque-like


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Desquamative gingivitis is a clinical descriptiveterm that doesnt infer any specific underlying

pathology (so that it has many causes!)

Gingival lesions may occuralone (in 10% ofcases) orwith other oral lesions

Prevalence:o Lichen planus is a relatively common disease (affects 0.5-2% of general population)o There's a worldwide distributiono Peak incidence is found between ages 30-50o Lesions are more common in females (60% of cases)o Oral lesions are detected in ~50% of patients with initial skin lesionso Skin lesions are detected in ~10-50% of patients with initial oral lesions!!

This may be due to:

- Asymptomatic nature of oral lesions in many cases- Inconstant relationship of oral and skin lesions (oral lesions may occur BEFORE, AFTER

or AT THE SAME TIME as skin lesions)

Histopathological features:o Orthokeratosis or Parakeratosiso Epithelial atrophy or acanthosiso Acanthosis results in irregular elongation and widening

of the rete ridges in asaw-tooth pattern

o Dense, well-defined band of subepithelial mononuclearinfiltrate (mainly T-lymphocytes)

o Liquefactive degeneration of the basalcell layer withedema and lymphocytic infiltration

o The degenerating cells appear as hyaline shrunken bodies,called Civatte bodies

o Basal cell degeneration may result in subepithelial bullaeformation and ulceration because of the lack of cohesion

between epithelium and lamina propria following the

degeneration


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o Oral lesions may show little superficial resemblance to skin lesions clinically even though thebasic histological changes are similar,because of the modifying environment of the oral cavity

by:

- Continuous presence of saliva- Secondary infection by oral organisms- Repeated trauma

o Almost all cases run a benign courseo Malignant transformation has been described in a very small proportion (0.5%-2.5% over 5 years)o Some studies suggest that atrophic/erosive forms are more likely for such transformation

because of the decreased barrier presented to potential carcinogenso Other studies found malignant transformation more likely with plaque lesions

Etiology & pathogenesis:o It is NOT fully understoodo In most cases the precipitating factors are unknown and the disease is Idiopathico It is widely accepted that cell-mediated immune responses to an external antigen, or internal

antigenic changes in epithelial cells, are involved since response resembles type IV

hypersensitivity reaction which is T-cell mediated

o Cytotoxic lymphocytes damage the basal epithelium** Possible immunological mechanism in lichen planus:

External antigen challenge and/ormodified antigenic structure of epithelial cells induces

cytokines release from langerhans cells & keratinocyteschemotaxis oflymphocytes which

accumulate in the basement membrane zone & basal epithelium antigen presentation to CD4helper cells activation of CD8 Cytotoxic cells basal cell degeneration

o Lichen planus has been associated with some systemic diseases, in many of these, a cause-and-effect relationship has not been established (e.g. there is strong association of the disease with

chronic liver disease especially hepatitis C virus)

o Oral & skin lesions resembling lichen planus are also seen as a part of graft-versus-hostreaction (immune reactions in patients receiving transplants), in such cases, the transplanted T

cells react to antigens on host epithelial cells

o Lichenoid reaction:- Lichenoid = lichen-like- In some patients, lesions similar to lichen planus may appear

triggered by hypersensitivity reaction (IV) to certain drugs

(NSAIDs) or dental materials(amalgam)

- These lesions are clinically and histologically similar toLichen planus, but tend to be reversible so that they resolve

upon withdrawal of the offending agent

** Lichenoid reactions aren't idiopathic as lichen planus

** Lichenoid reactions are usually unilateral while lichen planus is usually bilateral


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Lupus Erythematosus (LE): It is a chronic mucocutaneous disease that involves skin and mucous membranes and believed to be

due to an autoimmune process

It has two main forms:1. Chronic discoid lupus erythematosus localized2. Systemic lupus erythematosus disseminated

Lesions are more common in females Clinical features:

1. Chronic discoid lupus erythematosus (DLE):o It is the localized form of the disease in which skin lesions occur without any systemic

involvement

o Site: lesions are usually restricted to the skin, and confined to the faceo

Clinical presentation:- Skin lesions:

Lesions appear as scalyor crusted red patches that heal with scar Sometimes facial lesions have a symmetrical distribution over the nose and cheek,

the so-called (butterfly rash)

** This butterfly rash can be seen in both forms

Follicular plugginghair follicles being plugged and prevented from going out andgrowing leading to hair loss)

- Oral lesions: Lesions are found in up to 50% of cases Buccal mucosa is most frequently affected There's considerable variation in the usual

presentation of oral lesions but the most common

is a discoid area of Erythema or ulceration

surrounded by white Keratotic border

sometimes with radiating striae (resembling

lichen planus)

o Histopathology:- Orthokeratosis or Parakeratosis


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- Epithelial atrophy or acanthosis- Keratin plugging- The subepithelial lymphocytes are aggregated

in follicles and dont show the clear band-like

arrangement as in lichen planus- Liquefactive degenerationof basal cells- Circulating autoantibodies are found in one-

third of patients

2. Systemic Lupus Erythematous (SLE):o It is the disseminated form of the disease in which

skin lesions occur with systemic involvement

o Site: skin lesions typically affect the facecheeks and the hands

o Photosensitivity may be implicated in lesionseruption

o May be fatalo Clinical presentation:

- Skin lesions: Skin rashes (maculopapular) Sometimes facial lesions have a symmetrical distribution over the nose and cheek,

the so-called (butterfly rash)

- Oral lesions: They are variable Superficial erosions and erythematous patches on the buccal mucosa White Keratotic areas are not so frequently seen as in DLE

o Histopathology:- Non specific diffuse inflammatory infiltrate- A variety of circulating autoantibodies are almost always present (e.g. antinuclear

antibodies (ANAs))

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5- Dermatological Causes of White Patches (1) (1)