Inflammatory Skin Diseases Flashcards
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.
Thickening (acanthosis)
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?
Eczema
What are the types of eczematous dermatitis?
Allergic contact dermatitis
Irritant contact dermatitis
Atopic eczema
Drug-related eczema
Photoeczematous 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?
Scalp
Ears
Medial eyebrows
Upper eyelids
Nasolabial folds
Central chest
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?
Teens/eary adults
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
Psoriasis inversa
What are the histology features of classic plaque psoriasis?
Parakeratosis
Loss of granular layer
Thinning of suprapapillary plates
Increased mitotic figures in the basal layer
Munro’s microabscesses
Spongiform pustule of kogoj
Dilated and tortuous capillaries