Derm Flashcards
What are the common types of dermatitis (eczema)?
Allergic contact dermatitis
Irritant contact dermatitis
Atopic dermatitis
Dyshidrotic dermatitis
Lichen simplex chronicus
What is this? How does it present?
Allergic contact dermatitis
Presentations: pruritis (common to all dermatites), vesicular/bullous formation, and commonly lichenification
What mediates allergic contact dermatitis? Timeline?
type IV hypersensitivity that presents in two phases
1) sensitization (induction)- 10-14 days or 12-48 hrs upon re-exposure
2) elicitation (challenge)
Common causes of ACD?
- Rhus dermatitis (poison ivy, poison oak- all contain urushiol)
- fragrances
- Nickel
How does a Rhus allergy present?
initial episode occurs 7-10 days after exposure and within hours upon re-exposure and lastly 10-21 days depending on the severity with the initial exposure being the most severe and presents as:
linear erythema that can blister
How is Rheu dermatitis treated?
Minor supportive care with topical steroids and anti-histamines
What causes latex allergy?
Latex allergy may present as a delayed (on the dorsum of the hand) or immediate hypersensitivity
Key points about acute dermatitis
-1 of 2 types of contact dermatitis that occurs primarily due to a type IV hypersensivity (except latex- I or IV) that can be diagnosed using a Patch test and generally requires supportive care, topical steroids, and antihistamines
What is Irritant contact Dermatitis?
A non-immuologic, inflammatory rxn resulting from exposure to a toxic substance like bleach that can occur due to single exposure but is most commonly due to repeated exposure and is strongly associated with major risk factors that impair the barrier function of the skin like atopic dermatitis
What are the most sensitive areas of the body for an ICD?
face, neck, scrotum, and dorsal hands
How is ICD treated?
removal of the irritant, topical steroid therapy to reduce inflammation, emollients to improve barrier function, and prolonged caution is advice because the skin remains vulnerable to flares of dermatitis for prolonged periods
What is Atopic Dermatits?
a very common chronic, pruritic, inflammatory disease that is characterized by periods of remission and exacerbations and xerosis BUT that can present differently based on the age group affected
How does atopic dermatitis typically present in infants? What areas of the body?
erythematous plaques common on the face (cheeks, forehead, scalp), and extensor surfaces
How does atopic dermatitis typically present in older children? What areas of the body?
lichenified, eczematous plaques in flexural areas of the neck, elbows, wrists, and ankles
How and where does atopic dermatitis tend to present in adults?
Lichenification in flexural regions and involvement of the hands, wrists, ankles, feet and face (particularly the forehead and around the eyes)
What mediates AD?
AD is considered to be multifoactorial (skin function, genetics, etc.) and part of the inflammatory (type I) hypersensitivity triad that includes allergic rhinitis and bronchial asthma (a Hx of these illnesses is often present)
What is a major pre-disposing factor for developing AD?
Inherited reduction or loss of the epidermal barrier protein filaggrin is a major predisposing factor for AD
Favors Th2-mediated immunity
How is AD treated?
- avoidance of trigger factors
- anti-inflammatory therapy to control subclinical inflammation as well as overt flares (prednisone)
- in selected cases, adjunctive or complementary modalities such as Topical tacrolimus or pimecrolimus
90% of atopic dermatitis skin lesions are colonized with microbes, usually _______
Staphylococcus aureus (Presence of erosions, drainage with yellow crusting may indicate an infection)
What is Eczema Herpeticum?
A severe herpes simplex virus infection in an atopic patient that presents with multiple wide spread monomorphic, “punched-out” discrete erosions with hemorrhagic crusting
Severe cases may require hospitalization and IV anti-viral medications
What is this? Describe them. When do you see them?
Nummular Dermatitis/Discoid eczema- presents as Coin-shaped, well-demarcated plaques with scale and possibly tiny vesicles, cracking or crusting that are very pruritic, show, spongiotic dermatitis, and are more common in winter
Describe Dyshidrotic Eczema/Pompholyx?
a chronic, relapsing palmoplantar eczematous dermatosis characterized by firm, pruritic vesicles and bullae. While the vesicles are due to spongiosis within the epidermis, their intact nature is explained by the thick tear-proof horny layer in these sites. Dyshidrotic eczema is not an independent disease entity because it is often a manifestation of other types of eczema, especially atopic dermatitis and irritant or allergic contact dermatitis.
T or F. Dyshidrotic eczema causes disturbance of sweat gland function
F.
What is this?
Lichen Simplex Chronicus- Chronic, intensely pruritic skin condition triggered by repeated rubbing and scratching of the skin that typically presents with a solitary, well-defined, pink to tan, thick, and lichenified plaque
Commonly on the lateral neck, scrotum/vulva, and dorsal foot
What are the papulosquamous skin diseases?
-Psoriasis
-Seborrheic dermatitis
-Pityriasis rosea
-Lichen planus
What is Psoriasis?
A chronic immune-mediated disease with predominantly skin and joint manifestations that can present at any age, but occurs most commonly in two peaks: ages 20-30 and ages 50-60 and has a strong genetic component
What are the five main variants of psoriasis?
plaque-type,
guttate,
pustular,
inverse
erythrodermic psoriasis
What is this? Describe it. Where is it common?
Plaque psoriasis, the most common variant (90%) of psoriasis that is most prevalent on the scalp, extensor surfaces of the extremities, and the periumbilical and sacral trunk; they rarely occur on the face, or on intertriginous areas of the body (inverse psoriasis).
What is the the Koebner phenomenon
Plaque psoriasis arising at sites of trauma
What is this?
Ausptiz Sign
How does the second most common variant of psoriasis, Guttate psoriasis, present?
It occurs more commonly in young adults, and it presents with multiple small “drop-shaped” erythematous scaly plaques diffusely on the body, most frequently on the trunk and is often preceded by streptococcal infections, especially pharyngitis.
What is this?
Inverse/Flexural psoriasis- Erythematous plaques in the axilla, groin, inframammary region and skin folds that may lack scale due to moistness of area and are often symmetric
Describe pustular psoriasis
Disease characterized by superficial pustules that may be localized on the plams and soles or they may be generalized and are often triggered by corticosteroid withdrawal
What are some other common manifestations of psoriasis?
- mucosal and nail changes.
- The dorsal tongue may exhibit geographic, annular white patches.
•Psoriatic nail changes include “oil spots,” nail pitting, distal onycholysis, and accumulation of subungual debris.
-arthritis
How does psoriatic arthritis present?
The most common presentation is asymmetric oligoarthritis of the small joints of the hands (sausage hands- below) and feet
- Psoriatic arthritis may also present as isolated monoarthritis, sacroiliitis, arthritis mutilans, or enthesitis.
- In addition, psoriatic patients appear to be at an increased risk for developing obesity, diabetes mellitus, hyperlipidemia, hypertension, and cardiovascular disease
Describe Seborrheic dermatitis
An inflammatory reaction to the Malassezia (Pityrosporum ovale) yeast that thrives on seborrheic (oil-producing) skin and presents as erythematous scaling patches
In infants this presents with “cradle cap”, pink to yellow macules and patches with white greasy scales on the scalp, face, and diaper area
On the chest, it appears more central over the sternum
How does Pityriasis Rosea present?
Usually an asymptomatic disease, but flu-like symptoms including malaise, nausea, loss of appetite, etc. and even fever and LAD can be seen AND
classically starts with a ‘herald’ patch and then a secondary phase with a symmetric, salmon-colored ‘Christmas tree” pattern rash
Pityriasis rosea
Lichen planus
Lichen planus
How does scabies infection occur? Patient population?
Can affect anyone but more common in women, children, immunocompromised individuals, and close groups of people and occurs from direct contact with an infected individual or fomites (below)
How does scabies present?
There is typically a 3-4 week incubation period from infection initially (or as fast as 1-2 days with re-infestation) that results in papule formation throughout the body that are characteristically more itchy at night and may show pathognomonic BURROWS
What are these?
Burrows - linear markings in the skin due to the movement of the mite. They are 1-10 mm in length and are most readily found in the interdigital spaces, wrists and elbows
How should suspected scabies be addressed?
perform a mineral oil preparation on the patient.
•You use a 15-blade scalpel and scrape a burrow on the skin. The scraped material is placed on a slide and a drop of mineral oil is added. A cover slip is placed on top and you see the image below when you look through the microscope.
What are hyperkeratotic scabies, formerly called Norwegian scabies?
Immune suppressed or neurologically impaired individuals are at increased risk of developing crusted scabies that are far more difficult to treat
How does head lice present?
Frequently pruritic, associated with posterior cervical LAD, and dermatitis on the posterior neck
How is Pediculosis treated?
It is prudent to re-treat with topical therapies 7-9 days after initial therapy to kill the newly hatched lice
- Use OTC permethrin 1% or pyrethrins when resistance is not suspected.
- Use malathion 0.5% when resistance to permethrin or pyrethrins is documented or when treatment with these products fails.
Adjunctive nit combing can be performed.
Occlusive methods have also been used to suffocate head lice using substances such as petroleum jelly and mayonnaise, but study results have been variable.
Describe the transmission of bed bugs
Bed bugs may be spread during travel on clothing, bedding, mattresses, and laundry, etc and tend to stay hidden during the day and feed at night
Bites may be multiple in a linear array; referred to as “breakfast, lunch and dinner”
