CM- Approach to Scaling Disorders Flashcards
Define the terms guttate, nummular, pityriasis.
Guttate - drop shaped
Nummular- shaped like a coin
Pityriasis- bran-like flakes of scale
What is a scale?
piece of stratum corneum. Usually they are so small that they go undetected, but in disorders, abnormal stratum corneum accumulates and forms visible flakes
What are the 3 main functions of skin?
- mechanical protection
- prevent water loss
- immunological defense
Describe the normal development of the skin [keratinization].
What 3 disruptions to keratinization can lead to scaling?
Pool of stem cells in basal cells mature as they rise to the stratum corneum. The end result takes 2 weeks and is an anucleate, non-viable corneocyte that populates the most superficial layer of the epidermis [80% protein, 20% lipids]
Shedding takes 2 weeks after degradation of the lipids and cell adhesion proteins.
Scaling can be caused by:
- increased proliferation of basal keratinocytes
- abnormal maturation
- increased retention of corneocytes
What is the effect of inflammation on scaling?
Inflammatory conditions –> released cytokines–> increased proliferation of basal keratinocytes
This results in excess, incompletely matured keratinocytes–> nucleated stratum corneum [parakeratosis]
What is parakeratosis?
What is the cause?
It is nucleated stratum corneum cells. It is caused by increased proliferation of basal keratinocytes leading to excess of incompletely matured cells
What is the pathogenesis of psoriasis?
- genetic predisposition [HLA-B27]
2. immune triggers that inappropriately activate the immune response
What is the histology of psoriasis?
- inflammatory cells in the epidermis and dermis
- accumulation of neutrophils [munro’s microabsesses]
- increased mitoses in keratinocytes, fibroblasts, endothelial cells
- thickened epidermis [acanthosis]
- retention of nuclei in the horny layer with absence of granular layer
- parakeratotic hyperkeratosis [nucleated stratum corneum]
What are the 5 clinical patterns of psoriasis?
- plaque type [classic and most common]
- guttate type [drop-shaped]
- Inverse [ axilla, gluteal cleft] macerated/less obvious
- erythrodermic -diffuse over whole body
- pustular - localized to palms or soles
What 3 diagnostic clues point to psoriasis?
- Koebner phenomenon - primary lesion induced by trauma to the skin
- Nail involvement - pits, oil-drop changes, onycholysis [detachment of nail from nail bed]
- arthritis [asymmetric]
What areas of the body tend to be affected by psoriasis?
- scalp
- nails
- sacral area
- extensor surfaces
- shins & knees
- elbows
- palms and soles
What is the pathogenesis of secondary stage syphilis?
Cutaneous dissemination of treponema pallidum
Describe the histology of secondary syphilis.
- epidermal hyperkeratosis [thickening of stratum corneum]
- perivascular monocytes, lymphocytes and plasma cells in the dermal layer
- dilation and proliferation of capillaries and lymphatics in the dermis
- silver stain shows spirochetes
What is the “classic” presentation of secondary syphilis?
- red/brown macules or papules on trunk AND extremities [freq. palms and soles]
- diffuse hair loss/ lateral 1/3 of eyebrow loss
- “great imitator” - can mimic:
- ptyriasis rosea
- guttate psoriasis
- lichen planus
- sarcoidosis - condyloma lata- vesicles/pustules or mucus patches
What is the histology of seborrheic dermatitis?
- parakeratosis focally around the edges of follicular ostia [opening where hair emerges from the follicle]
- spongiosis [intracellular edema] with neutrophilic infiltrate
What are common locations for seborrheic dermatitis?
- scalp
- eyebrows
- eyelids
- nasolabial folds
- ears
- sternum
- axillae
- submammory folds
- umbilicus
- groin
- gluteal creases
What are the 5 types of seborrheic dermatitis?
- Classic - “greasy” yellowish scales on face, dandruff on scalp
- infantile - prominent scalp involvement
- “sebopsoriasis”- mixed psoriasis and seborrheic dermatitis
- Erythroderma
- immunosuppressed have it florid and treatment resistant
What is the histology of pityriasis rosea?
- parakeratosis that is patchy or diffuse and contains serum
- spongiotic dermatitis with perivascular lymphocytic infiltrate
A patient presents with a herald patch [open ring] on the trunk with crops of smaller round to oval salmon-color patches following lines of cleavage [“christmas tree pattern”]. There are peripherally attached thin scales.
What does this pattern describe?
Pityriasis rosea
Describe the histology of pityriasis lichenoides.
- parakeratosis and spongiosis in the epidermis
- keratinocyte necrosis
- erythrocytes in the epidermis
- wedge-shaped inflammatory cell infiltrate in the dermis
Describe the acute and chronic presentation of pityriasis lichenoides.
Acute - bright red, erythematous papules that can erode/ulcerate
Chronic:
- red-brown lesion
- micaceous [aluminum silicate chalky residue] scale
- post inflammatory hyperpigmentation
You are looking at a slide and see:
- irregular acanthosis with hypergranulosis
- hyperkeratosis
- Civatte/colloid bodies
- band like infiltrate at dermal-epidermal junction
- pigment incontinence - loss of melanin from basal cells with accumulation in upper dermis melanophages
What is the likely diagnosis?
Lichen planus
A patient presents with flat-topped, polygonal violaceous papules that coalesce into plaques. The surface has a fine scale with a network of white lines [Wickham striae] going through.
The lesions are primarily on the wrist, pretibial area and mucus membranes including oral lesions - buccal mucosa with white papules in reticular pattern. The patients nails are rough with longitudinal ridging, thinning and pterygium formation.
What does the patient have?
Lichen planus
What is the histology of lichen simplex chronicus?
- Hyperplasia of the epidermis
- hyperkeratosis
- hypergranulosis
- acanthosis
- elongated and irregular rete ridges
- spongiosis
A patient present with a thickened and hyperpigmented plaque. Skin lines are visible and the area is sharply demarcated. There is some excoriations and pruritus is a prominent feature. What is the likely diagnosis?
Lichen simplex chronicus
Most ichthyoses have non-specific histology but share what 2 features?
Which 2 types of ichthyoses have unique features and what are they?
- compact hyperkeratosis
- normal or thickened granular layer
Ichthyosis vulgaris - decreased or absent granular layer
Epidermolytic hyperkeratosis-
- hypergranulosis with giant keratohyalin granules
- keratinocyte lysis resulting in subcutaneous vacuolization and vesicles
You look at histology of a skin lesion and see:
- hypergranulosis with giant keratohyalin granules
- keratinocyte lysis with subcutaneous vacuolization and vesicles
What is the diagnosis?
Epidermolytic hyperkeratosis
What is the inheritance pattern of ichthyosis vulgaris?
What is the mutation in?
What is the presentation?
It is an autosomal dominant mutation in filaggrin.
Patient will present with non-inflamed scaling that can be fine or thick. Patients can also present with:
- atopic dermatitis
- keratosis pilaris
- hyperlinearity
- thickening of palms and soles
What is the mutation in X-linked ichtyosis? What area of the body is most affected? What areas are spared?
It is a mutation in steroid sulfatase.
Neck is almost always involved
Palms, soles, and face are spared
What is the inheritance pattern and mutation in lamellar ichtyosis?
How do newborns present?
How do adults present?
autosomal recessive mutation in transglutaminase 1, ABCA12.
Newborns have colloidion membrane
Adults have thick, plate-like scale
What is the inheritance pattern and mutation in epidermolytic hyperkeratosis?
Autosomal recessive mutation in Keratin 1 or 10
Newborns present with blisters and erosions
Later in life, erosions are replaced by hyperkeratosis
What do you do if there is a possibility of fungal origin for a scaling disorder?
KOH scraping for microscopic analysis
How does scaling of papulosquamous lesions present?
predominant papules/plaques with prominent scaling
How does scaling of erythrodermic lesions present?
widespread erythema with fine/subtle scaling
Differentiate acute, subacute and chronic dermatitis.
Acute -very inflamed/exudative [oozing, weeping, blisters]
Subacute - intermediate
Chronic- dry, scaly, lichenification
