Flashcards in Inflammatory Skin Diseases Deck (58):
What is spongiotic dermatitis?
A histological term describing conditions which are characterized by spongiosis (intracellular oedema within epidermis causing keratinocytes to be pushed apart)
What changes accompany spongiotic dermatitis?
Inflammatory cells within the epidermis and around the superficial dermis.
Hyperkeratosis (increased keratin in stratum corneum)
Parakeratosis (retention of nuclei in stratum corneum)
What does keratinocyte exocytoses look like on histology?
White spaces between epidermal cells.
What are the histology features of spongiotic dermatitis?
Keratinocytes pushed apart by oedema fluid
Parakeratosis (nuclei stained within stratum corneum due to abnormal maturation of keratinocytes)
Inflammatory cells (Lymphocytes and eosniphils in spongiotic area)
Inflammatory infiltrate around superficial blood vessels within dermis
What kind of condition commonly shows the spongiotic dermatitis histological pattern?
What are the types of eczematous dermatitis?
Allergic contact dermatitis
Irritant contact dermatitis
Nummular ("Discoid") eczema
What are the features of atopic eczema?
Intense pruritus and a chronic course.
Onset usually in infancy or childhood
Often accompanied by other atopic disorders
Atopy is linked to presence of allergen specific serum IgE antibodies
Both a genetic predisposition and environmental triggers have pathogenic roles in AtopicDermatitis.
What are the types of skin manifestations caused by atopic eczema?
Acute lesions: edematous, erythematous
Subacture lesions: Erythematous patches or plaques with scaling and variable crusting
Chronic lesions: Thickened plaques with lichenifcation as well as scalings.
Small perifollicular papules are especially common in patients with darkly pigmented skin.
What genetic factors are related to atopic eczema?
Loss-of-function variants in the flaggrin gene (FLG) which encodes a protein important to epidermal barrier function
What are the types of contact dermatitis?
Irritant contact dermatitis (ICD) which makes up 80% of contact dermatitis secondary to a local toxic effect caused by a topical substance of physical insult.
Allergic contact dermatitis is the other 20% caused by delayed type hypersensitivity reaction to substance.
What information is used to diagnose contact dermatitis?
The location of the dermatitis (eg watch area or deoderant area)
What is seborrhoeic dermatitis?
Common disorder with both an infantile and adult form.
Possibly related to sebum contents and malassezia species.
What condition is seborrheic dermatitis commonly associated with?
HIV infection or a neurological disorder
What is the distribution of seborrhoeic dermatitis commonly?
What do seborrhoeic dermatitis lesions look like?
Pink-yellow to red-brown with greasy scale
On the scalp involvement tends to be more diffuse
What does histology show with seborrhoeic dermatitis?
Hyperkeratosis and parakeratosis around hair follicles
Mild spongiosis (it is considered a spongiotic dermatitis histologically)
What is psoriasis?
Common chronic inflammatory dermatosis that appears to have autoimmune basis
Can affect any site variably and can be associated with arthritis
What stage of life does psoriasis most commonly show up?
6th decade of life
What causes psoriasis pathophysiologically?
Linked to certain genes within the HLA locus. Affects sensitized populations of CD4+ Th1 and Th17 cells and activated CD8+ cytotoxic effector T cells enter the skin and accumulate in epidermis which then create an abnormal environment by stimulating secretion of cytokines and growth factors that indicate keratinocyte proliferation resulting in the characteristic lesions.
What do psoriasis plaques look like?
Raised, sharply demarcated silvery scaled lesions.
Where are psoriasis lesions commonly located?
Scalp, extensor surfaces, lower back and umbilicus
Koebnerisation - lesions can appear at sites of previous trauma.
What are the types of psoriasis?
Guttate psoriasis (Small papules over trunk and proximal extremities in younger patients)
Pustular psoriasis (pustules over the trunk and extremities associated with fever and can progress to erythroderma)
Psoriatic erythroderma (erythema over entire skin surface, desquamation and systemic symptoms)
Palmoplantar pustular psoriasis
What are the histology features of classic plaque psoriasis?
Loss of granular layer
Thinning of suprapapillary plates
Increased mitotic figures in the basal layer
Spongiform pustule of kogoj
Dilated and tortuous capillaries
What are the histological features of guttate psoriasis?
Mounds of parakeratosis
Acanthosis with mild spongiosis
Lymphocytic and neutrophilic infiltrate
What are the histological features of pustular psoriasis?
Spongiform pustules that expand to become larger macropustules.
What are acute eczema lesions?
Edematous, erythematous papules and plaques that may have vesiculation, oozing and crusting.
What are Subacute eczema lesions?
Erythematous patches or plaques with scaling and variable crusting
What are chronic eczema lesions?
Thickened plaques with lichenification as well as scaling
What is rosacea?
A form of chronic rash on the face especially its central portion which usually sets in during the 4th decade of life
How severe is rosacea?
Highly variable from a few papulopustules to extreme distortion of the nose
What causes rosacea?
Alterations in innate immunity
Demodex mites and commensal bacteria
What are the types of rosacea?
What are the histological features of rosacea?
Telangiectatic blood vessels (widened blood vessels causing reddening of skin)
Dilated hair follicles
Demodex mites within hair follicles
What is urticaria?
Hives which is caused by localized mast cell degranulation and dermal microvascular hyperpermeability.
What are pruritic oedematous plaques that cause hives called?
Which age groups are most susceptible to urticaria?
20 to 40 years
Which areas are most prone to urticarial eruptions?
Any area exposed to pressure such as trunk, distal extremities, and ears
What is closely related to urticaria?
Angioedema, characterized by oedema of the deeper dermis and the subcutaneous fat.
What is the most important feature of urticaria?
Lesions develop and fade within hours or less and episodes may last for days -> months.
What are the types of urticaria as classified by aetiology?
Mast cell-dependent, IgE-dependent (normal type I hypersensitivity)
Mast cell-dependent, IgE independent (Degranulation directly triggered by substance)
Mast cell-independent, IgE independent (Substances directly dilate blood vessels and cause urticaria)
What abnormalities are seen in urticaria histology?
Very subtle changes.
Collagen fibers are pushed apart by tissue oedema
Mild perivascular infiltrate of inflammatory cells including neutrophils and eosinophils
What is vasculitis?
Inflammatory infiltrate that targets blood vessels and leads to destruction of blood vessel walls.
Does cutaneous vasculitis occur in isolation?
It can occur in isolation or together with involvement of other organs
What basis is used to classify vasculitides?
Based on the size of the vessels affected.
What blood vessels are most often involved in cutaneous vasculitides?
Small blood vessels
What is leucocytoclastic vasculitis?
Vasculitis in small blood vessels within dermis caused by circulating immune complexes resulting in a cutaneous reaction pattern.
What causes lleucoytoclastic vasculitis?
Idiopathic in 40% of cases and can also be caused by:
Drugs, infection, mixed cryoglobulinaemia, connective tissue disease, henoch-schonlein purpura, systemic vasculitis, malignancy
What is mixed cryoglobulinaemia?
Proteins precipitating out of blood at certain temperatures
What is henoch-schonlein purpura?
IgA mediated problem
What are the features of leucocytoclastic purpura?
Palpable purpura is the classic manifestation
Typically affects lower legs
What are the histological features of leucocytoclastic vasculitis?
Inflammation around small blood vessels with damage to endothelium
Nuclear debris from breakdown of neutrophils
Fibrin deposition reflecting damage to endothelium. (appears bright pink around blood vessels)
Infiltration of vessel walls by neutrophils
What does endothelial damage in vasculitis look like?
Erythrocytes in dermis
What does histology do in the diagnosis of vasculitis?
Confirms or denies the presence of vasculitis
Tells us the nature of the inflammatory process
Tells us the type and size of vessels affected
What type of biopsy must be taken for vasculitides?
A deep incisional biopsy including subcutaneous fat and larger vessels
What else must be taken in conjunction with biopsy for accurate diagnosis of cutaneous vasculitides?
Serology and immunofluorescence
What types of vasculitis could affect larger vessels in the skin?
ANCA-associated vasculitis (Wegner's, Churg-Strauss, microscopic polyangiitis)
Polyarteritis nodosa (Segmental vasculitis affecting medium sized vessels including small arteries in the deep dermis and subcutis)
What is the ideal method of taking an incisional biopsy?
Most of the biopsy should include the affected tissue