Immune-mediate Skin Disease Flashcards
CIMD
Cutaneous Immune-Mediated Disease
Diverse set of RARE conditions
Factors affects presentation of CIMDs
Target tissue
Predominant hypersensitivity type
Target tissue for CIMDs
Desmosomal proteins in the upper epidermis
Cells of the basal epidermis
Sebaceous glands
Dermal skin vessels
Subcuticular fat
Hypersensitivity types involved in CIMDs
Type 2 - Antibody Cytotoxicity
Type 3 - Immune complexes
Type 4 - T-Cell mediated
Pemphigus Foliaceous target tissue
Desmosomal proteins in upper epidermis
Pemphigus Foliaceous mechanism
Type II - Antibody cytotoxicity
Pemphigus Foliaceous presentation
Pustules rapidly developing into crusts
Leaves erosions
Doesn’t form around a single follicle
Pemphigus Foliaceous differential diagnosis
Superficial pyoderma
* Directly associated with one follicular unit
Desmosome
- Specialized and highly ordered membrane domains
- Mediate cell-cell contact and strong adhesion
- Provide anchorage sites for intermediate filaments
Facial cutaneous lupus erythematosus target tissue
Epithelial cells
Facial cutaneous lupus erythematosus mechanism
Type IV - T-Cell mediated
Facial cutaneous lupus erythematosus presentation
Damaged epithelium ulceration
Depigmentation
Facial cutaneous lupus erythematosus differential diagnosis
Mucocutaneous pyoderma
Epitheliotropic lymphoma
Vitiligo target tissue
Melanocytes
Vitiligo mechanism
Type II - Antibody cytotoxicity
Vitiligo presentation
Minimal inflammation
Hypopigmentation of epithelium
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)
