Specialized and highly ordered membrane domains Mediate cell-cell contact and strong adhesion Provide anchorage sites for intermediate filaments

Immune-mediate Skin Disease Flashcards by Eloise Newsom

CIMD

Cutaneous Immune-Mediated Disease
Diverse set of RARE conditions

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Factors affects presentation of CIMDs

Target tissue
Predominant hypersensitivity type

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Target tissue for CIMDs

Desmosomal proteins in the upper epidermis
Cells of the basal epidermis
Sebaceous glands
Dermal skin vessels
Subcuticular fat

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Hypersensitivity types involved in CIMDs

Type 2 - Antibody Cytotoxicity
Type 3 - Immune complexes
Type 4 - T-Cell mediated

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Pemphigus Foliaceous target tissue

Desmosomal proteins in upper epidermis

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Pemphigus Foliaceous mechanism

Type II - Antibody cytotoxicity

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Pemphigus Foliaceous presentation

Pustules rapidly developing into crusts
Leaves erosions
Doesn’t form around a single follicle

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Pemphigus Foliaceous differential diagnosis

Superficial pyoderma
* Directly associated with one follicular unit

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Desmosome

Specialized and highly ordered membrane domains
Mediate cell-cell contact and strong adhesion
Provide anchorage sites for intermediate filaments

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Facial cutaneous lupus erythematosus target tissue

Epithelial cells

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Facial cutaneous lupus erythematosus mechanism

Type IV - T-Cell mediated

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Facial cutaneous lupus erythematosus presentation

Damaged epithelium ulceration
Depigmentation

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Facial cutaneous lupus erythematosus differential diagnosis

Mucocutaneous pyoderma
Epitheliotropic lymphoma

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Vitiligo target tissue

Melanocytes

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Vitiligo mechanism

Type II - Antibody cytotoxicity

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Vitiligo presentation

Minimal inflammation
Hypopigmentation of epithelium

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Vitiligo differential diagnoses

Any inflammatory disease that causes depigmentation

Examples of dermal tissue targets

Isthmus of hair follicle
Hair bulb
Sebaceous glands
Dermal blood vessels
Anchoring fibrins (collagen VII)

Conditions targeting isthmus of hair follicle

Pseudopelade
Scarring alopecia

Conditions targeting hair bulb

Alopecia areata

Conditions targeting sebaceous glands

Sebaceous adenitis

Conditions targeting dermal blood vessels

Vasculitis
Atrophic skin disease
Ischaemic skin disease

Sebaceous adenitis target tissue

sebaceous glands

Sebaceous adenitis mechanism

Type IV - T-cell mediated

Sebaceous adenitis presentation

Broken hair Alopecia scale

Sebaceous adenitis differential diagnosis

Superficial pyoderma Dermatophytosis Many scaling diseases

Sebaceous adenitis pathogenesis

Gland is destroyed * No greasy material produced to allow hair to leave follicle without friction * Results in keratin brought out of follicle * Broken hairs * Secondary infections

Vasculitis target tissue

Dermal blood vessels

Vasculitis mechanism

Type II - antibody cytotoxicity +/- Type III - Immune complexes

Vasculitis presentation

Alopecia Necrosis Not pruritic

Vasculitis differential diagnosis

Any cause of alopecia Tumours Trauma

Pathogenesis of vasculitis

Reduced blood supply to skin Reduced growth of hair alopecia in atrophic skin

Panniculitis target tissue

Subcutaneous fat

Panniculitis mechanism

Unclear Pyogranulomatous inflammation

Panniculitis presentation

Soft-fluctuation nodules hat may rupture

Panniculitis differential diagnosis

Tumours Deep infections

Considerations of CIMDs

○ Cutaneous marker of a systemic disease ○ Accompanied by other apparently unrelated IMDs

Where else can vasculitis affect?

Kidneys - glomerulonephropathy Joints - Immune-mediated arthropathy Eyes - retinal haemorrhage

How to diagnose CIMDs

○ Exclusion of common differential diagnoses ○ Confirmation of correct histological pattern on histopathology ○ Occasionally need to rely on exclusion alone

Why is accurate diagnosis of CIMDs essential?

Most need treatment with drugs that cause varying degrees of immuno-modulatory drugs ○ Adverse effects are common ○ Incorrect treatment for CIMDs may worsen or fail to resolve many infectious diseases

Exclusion diagnosis

○ Careful history taking First lesions Speed of onset Comorbidity ○ Rule out the common differential diagnoses Skin scrapes & hair plucks Dermatophyte culture Cytology ± culture Test treatment (e.g. some parasites)