Pathology of Common

Dermatitides & Dermatoses

Pathology of Common

Dermatitides & Dermatoses

Mark R. Wick, M.D.Mark R. Wick, M.D.

“Papulosquamous” Dermatitides

Defined by clinical attributes, as slightly

elevated papular eruptions with scaling

These diseases include spongiotic, lichenoid, and psoriasiform dermatitides

from a pathological perspective

Defined by clinical attributes, as slightly

elevated papular eruptions with scaling

These diseases include spongiotic, lichenoid, and psoriasiform dermatitides

from a pathological perspective

1. Spongiotic dermatitides Contact dermatitis Eczema (atopic dermatitis) Superficial mycoses (dermatophytoses) Seborrheic dermatitis (acute/subacute) Pityriasis rosea Selected cases of secondary syphilis

2. Lichenoid dermatitides Lichen planus Lichen simplex chronicus (“neurodermatitis”) Lupus erythematosus (discoid or systemic) Dermatomyositis

3. Psoriasiform dermatitides Psoriasis vulgaris ANY CHRONIC SPONGIOTIC DERMATITIS

1. Spongiotic dermatitides Contact dermatitis Eczema (atopic dermatitis) Superficial mycoses (dermatophytoses) Seborrheic dermatitis (acute/subacute) Pityriasis rosea Selected cases of secondary syphilis

2. Lichenoid dermatitides Lichen planus Lichen simplex chronicus (“neurodermatitis”) Lupus erythematosus (discoid or systemic) Dermatomyositis

3. Psoriasiform dermatitides Psoriasis vulgaris ANY CHRONIC SPONGIOTIC DERMATITIS

“Papulosquamous” Dermatitides: Common Representative Examples

SPONGIOTIC DERMATITIDESSPONGIOTIC

DERMATITIDES

Spongiotic Dermatitides:General Histologic Features

1. Variable parakeratosis: retention of nuclei in superficial cornified epidermal cells

2. Spongiosis: Presence of edema fluid between individual epidermal cells, which may progress to formation of vesicles (microscopic intraepidermal “blisters”)

3. Inflammation in the epidermis and dermis, with perivascular dermal accentuation. It is usually chronic in nature (i.e., featuring lymphocytes and histiocytes), but small numbers of neutrophils & eosinophils may also be observed

1. Variable parakeratosis: retention of nuclei in superficial cornified epidermal cells

2. Spongiosis: Presence of edema fluid between individual epidermal cells, which may progress to formation of vesicles (microscopic intraepidermal “blisters”)

3. Inflammation in the epidermis and dermis, with perivascular dermal accentuation. It is usually chronic in nature (i.e., featuring lymphocytes and histiocytes), but small numbers of neutrophils & eosinophils may also be observed

1. Allergic Contact Dermatitis: Eosinophils in the epidermis

2. Seborrheic Dermatitis: Accentuation of parakeratosis

around hair follicle ostia, with or without neutrophils

3. Pityriasis rosea: Extravasation of red cells in the epidermis

4. Dermatophytoses: Neutrophils in the epidermis, along with intracorneal PMNs; fungi are visible with the GMS stain

5. Syphilis: Spirochetes in epidermis with the Warthin-Starry/Steiner silver stains

1. Allergic Contact Dermatitis: Eosinophils in the epidermis

2. Seborrheic Dermatitis: Accentuation of parakeratosis

around hair follicle ostia, with or without neutrophils

3. Pityriasis rosea: Extravasation of red cells in the epidermis

4. Dermatophytoses: Neutrophils in the epidermis, along with intracorneal PMNs; fungi are visible with the GMS stain

5. Syphilis: Spirochetes in epidermis with the Warthin-Starry/Steiner silver stains

Spongiotic Dermatitides:Histologic Nuances

LICHENOID DERMATITIDES

LICHENOID DERMATITIDES

Lichenoid Dermatitides:General Histologic Features

1. Damage to basal epidermal keratinocytes, with secondary “vacuolar” (clear-cell) change in their cytoplasm

2. Infiltrate of lymphocytes + plasma cells in a “band” beneath the epidermis, with or without direct involvement of the

dermoepidermal junction 3. Death of keratinocytes near the

stratum basalis, with formation of “cytoid” bodies

4. Variable atrophy or hyperplasia (acanthosis) of the epidermis

1. Damage to basal epidermal keratinocytes, with secondary “vacuolar” (clear-cell) change in their cytoplasm

2. Infiltrate of lymphocytes + plasma cells in a “band” beneath the epidermis, with or without direct involvement of the

dermoepidermal junction 3. Death of keratinocytes near the

stratum basalis, with formation of “cytoid” bodies

4. Variable atrophy or hyperplasia (acanthosis) of the epidermis

1. Lichen Simplex Chronicus: Vertical striation of collagen surrounding the rete ridges, in the papillary

dermis 2. Lichen planus: Irregular “sawtooth”

hyperplasia of the epidermis with irregular thickness of

the stratum granulosum and a lack of parakeratosis

3. Lupus erythematosus/Dermatomyositis: Atrophy of the epidermis

with thickening of the epidermal basement membrane; LE also shows dermal mucin deposition

1. Lichen Simplex Chronicus: Vertical striation of collagen surrounding the rete ridges, in the papillary

dermis 2. Lichen planus: Irregular “sawtooth”

hyperplasia of the epidermis with irregular thickness of

the stratum granulosum and a lack of parakeratosis

3. Lupus erythematosus/Dermatomyositis: Atrophy of the epidermis

with thickening of the epidermal basement membrane; LE also shows dermal mucin deposition

Lichenoid Dermatitides:Histologic Nuances

PSORIASIFORM DERMATITIDES

PSORIASIFORM DERMATITIDES

Psoriasiform Dermatitides:General Histologic Features

Psoriasiform Dermatitides:General Histologic Features

1. Regular acanthosis of the epidermis, but with suprapapillary thinning

2. Parakeratosis and/or orthokeratosis 3. Variable acute inflammation,

especially involving the epidermis & stratum corneum (“Munro” & “Kogoj” microabscesses)

4. Perivascular chronic dermal inflammation

5. Papillary dermal hypervascularity

1. Regular acanthosis of the epidermis, but with suprapapillary thinning

2. Parakeratosis and/or orthokeratosis 3. Variable acute inflammation,

especially involving the epidermis & stratum corneum (“Munro” & “Kogoj” microabscesses)

4. Perivascular chronic dermal inflammation

5. Papillary dermal hypervascularity

1. There are NO specific markers of psoriasis vulgaris; Munro & Kogoj microabscesses may be seen in other diseases as well, particularly in chronic dermatophytoses

2. “Suggestive” histologic features of acute or subacute spongiotic dermatitis are usually ABSENT in their chronic forms, yielding microscopic images which simulate that of psoriasis closely. Resulting differential diagnosis includes psoriasis, chronic eczema, chronic dermatophytosis, and chronic contact dermatitis

1. There are NO specific markers of psoriasis vulgaris; Munro & Kogoj microabscesses may be seen in other diseases as well, particularly in chronic dermatophytoses

2. “Suggestive” histologic features of acute or subacute spongiotic dermatitis are usually ABSENT in their chronic forms, yielding microscopic images which simulate that of psoriasis closely. Resulting differential diagnosis includes psoriasis, chronic eczema, chronic dermatophytosis, and chronic contact dermatitis

Psoriasiform Dermatitides:Histologic Nuances

Psoriasiform Dermatitides:Histologic Nuances

PRIMARY ACQUIRED BULLOUS

DISEASES OF THE SKIN

PRIMARY ACQUIRED BULLOUS

DISEASES OF THE SKIN

Primary Acquired Bullous Diseases of

the Skin

Primary Acquired Bullous Diseases of

the SkinPemphigus vulgarisBullous Pemphigoid

Epidermolysis bullosa acquisita

Dermatitis herpetiformis

Pemphigus vulgarisBullous Pemphigoid

Epidermolysis bullosa acquisita

Dermatitis herpetiformis

Disease Autoantibody Target(s) Pemphigus vulgaris Plakoglobin-130kD

complex in epidermal desmosomes Pemphigoid BP antigen in the lamina

lucida of the epidermal BMZ

Epidermolysis EBA antigen in sub-lamina bullosa acquisita densa

zone of epidermal BMZ Dermatitis Dermal papillary collagen (&

herpetiformisgliadin/endomysial proteins)

Disease Autoantibody Target(s) Pemphigus vulgaris Plakoglobin-130kD

complex in epidermal desmosomes Pemphigoid BP antigen in the lamina

lucida of the epidermal BMZ

Epidermolysis EBA antigen in sub-lamina bullosa acquisita densa

zone of epidermal BMZ Dermatitis Dermal papillary collagen (&

herpetiformisgliadin/endomysial proteins)

Primary Acquired Bullous Disorders of the Skin: Models

of Autoimmune Disease

Primary Acquired Bullous Disorders of the Skin: Models

of Autoimmune Disease

1. Pemphigus vulgaris-- Intraepidermal blisters, centered in the

suprabasal region; sparse mixed acute & chronic

inflammation 2. Pemphigoid-- Subepidermal blisters, filled

& undermined by PMNs, eosinophils, & lymphocytes

3. EBA-- Essentially identical to pemphigoid

4. Dermatitis herpetiformis-- Dense regional dermal infiltrates of PMNs, most

notable in upper dermal papillae & within blisters

1. Pemphigus vulgaris-- Intraepidermal blisters, centered in the

suprabasal region; sparse mixed acute & chronic

inflammation 2. Pemphigoid-- Subepidermal blisters, filled

& undermined by PMNs, eosinophils, & lymphocytes

3. EBA-- Essentially identical to pemphigoid

4. Dermatitis herpetiformis-- Dense regional dermal infiltrates of PMNs, most

notable in upper dermal papillae & within blisters

Primary Acquired Bullous Disorders of the Skin:

Histologic Features

Primary Acquired Bullous Disorders of the Skin:

Histologic Features

Disease DIF PatternPemphigus Intercellular labeling for

IgG, IgM, C’3 in epidermis

Pemphigoid/EBA Linear labeling of epidermal BMZ for IgG, IgM, C’3; collagen type IV in blister floor in BP & in

blister roof in EBA

Dermatitis Interrupted linear/granularherpetiformis labeling of epidermal

BMZ for IgA, C’3

Disease DIF PatternPemphigus Intercellular labeling for

IgG, IgM, C’3 in epidermis

Pemphigoid/EBA Linear labeling of epidermal BMZ for IgG, IgM, C’3; collagen type IV in blister floor in BP & in

blister roof in EBA

Dermatitis Interrupted linear/granularherpetiformis labeling of epidermal

BMZ for IgA, C’3

Primary Acquired Bullous Disorders of the Skin: Direct

Immunofluorescence

Primary Acquired Bullous Disorders of the Skin: Direct

Immunofluorescence

SELECTED VASCULAR

ABNORMALITIES OF THE SKIN

SELECTED VASCULAR

ABNORMALITIES OF THE SKIN

Leukocytoclastic Vasculitis: Pathologic

Features

Leukocytoclastic Vasculitis: Pathologic

Features Synonymous with “small vessel

vasculitis,” “hypersensitivity vasculitis,” or “Zeek’s vasculitis.” May be associated with underlying collagen vascular disease, Henoch-Schoenlein disease, or malignancy. Microscopic diagnosis is based on: Neutrophilic infiltration of small venules in dermis,

with karyorrhectic basophilic nuclear “dust” in interstitium

Extravasation of erythrocytes in the dermis Fibrinoid change in vessel walls is often seen but not

diagnostically necessary

Synonymous with “small vessel vasculitis,” “hypersensitivity vasculitis,” or “Zeek’s vasculitis.” May be associated with underlying collagen vascular disease, Henoch-Schoenlein disease, or malignancy. Microscopic diagnosis is based on: Neutrophilic infiltration of small venules in dermis,

with karyorrhectic basophilic nuclear “dust” in interstitium

Extravasation of erythrocytes in the dermis Fibrinoid change in vessel walls is often seen but not

diagnostically necessary

Urticarial Reactions:Microscopic Features

Urticarial Reactions:Microscopic Features

Principal histologic alteration is dermal edema, relating to “leakiness” of capillaries in the corium during reactions featuring local hyperhistaminosis

Dermal collagen bundles are splayed apart, by seemingly empty spaces

Variable numbers of eosinophils and neutrophils are seen around dermal venules & capillaries

Urticarial vasculitis is defined histopathologically as an “amalgam” of urticaria and leukocytoclastic vasculitis

Principal histologic alteration is dermal edema, relating to “leakiness” of capillaries in the corium during reactions featuring local hyperhistaminosis

Dermal collagen bundles are splayed apart, by seemingly empty spaces

Variable numbers of eosinophils and neutrophils are seen around dermal venules & capillaries

Urticarial vasculitis is defined histopathologically as an “amalgam” of urticaria and leukocytoclastic vasculitis