Aquifer - Dermatology Flashcards
The description of a primary lesion should begin with what 2 features?
Size
Raised or flat
Then describe shape, surface changes, arrangement, overall distribution
Examples of words to describe a lesion by type?
Primary lesion Size Consistency (rubbery, fluctuant, etc.) Color Secondary features (e.g., scaling, crusting, lichenification, excoriation, hypopigmentation
Words to describe arrangement?
Symmetric Scattered Clustered Linear Confluent Discrete
Words to describe location?
Scalp, trunk, extremities, sparing or including palms and soles
Words to describe pattern of distribution
Flexural surfaces Extensor surfaces Sun-exposed skin (photo-distributed) Dependent areas Dermatomal Blaschko-linear
Ways to describe progression over time?
Spreading head to toe or peripheral to central
Changing from papules to vesicles to crusts
Define macule.
Flat, circumscribed discoloration, <1 cm
Define patch.
Larger flat lesion of color change of the skin, >1 cm
Define papule.
Elevated, circumscribed solid lesion, <1 cm
Define plaque.
Broad, elevated lesion (or confluence of papules), >1 cm
Define vesicle.
Circumscribed, elevated lesion containing clear-colored fluid, <1 cm
Define bulla.
Larger, circumscribed, elevated lesion containing clear-colored fluid, >1 cm
Define pustule.
Elevated, exudative lesion (cloudy/yellow/green fluid), variable size
Define nodule.
Circumscribed, elevated lesion that involves the dermis and may extend into the subcutaneous tissue; majority is below the skin
Define wheal.
A blanching, circumscribed, edematous plaque, often with central pallor
May be white to pale red and often appear and disappear over a period of hours
Define telangectasia.
Dilation of superficial venules, arterioles, or capillaries visible on the skin.
Define petechiae.
Tiny, red or purple macules caused by capillary hemorrhage under the skin or mucous membrane that do not blanch
Define purpura.
Larger, purple lesion caused by bleeding under the skin. May be palpable, do not blanch
Define secondary lesions.
Changes that occur later in the course of a lesion or rash
Define scale.
Flakes of keratin that can fine or coarse, loos or adherent
Define crust.
Dried remains of serum, blood, or pus overlying involved skin
Define fissure.
Linear, often painful cleavage in the surface of the skin.
Define erosion.
Slightly depressed lesion in which all or part of the epidermis has been lost. Does not extend into the underlying dermis, so healing occurs without scar formation.
Define ulcer.
Depressed lesion extending into the dermis or subcutaneous tissue, may lead to scar formation
Define excoriation.
Traumatized, superficial loss of the skin, often linear, caused by scratching or rubbing
List the key findings in the diagnosis of an allergic reaction.
- Family history of atopy
- Recurrent rapid onset and resolution of rash (suggesting an acute, repeated response to some type of trigger)
- Pruritis (generally rules out diagnoses such as viral exanthems; likely due to histamine release from mast cells during an allergic inflammation)
- History of a therapeutic response to administration of antihistamine
DDx - Rash (school-age, 5-year-old)
- Roseola
- Papular urticaria
- Streptococcal infection
- Erythema multiforme
- Erythema infectiosum (fifth disease)
- Urticaria due to type 1 hypersensitivity
- Erythema migrans
- Drug eruption
Presentation of roseola?
Common in children <2 years
Viral exanthem for 1-4 days that classically follows 3-5 days of a high fever
As the fever resolves, patients develop a pink, maculopapular rash that starts on the trunk and may spread to the face and extremities
Presentation of papular urticaria?
Pruritic papular lesions 3-10 mm in diameter
Caused by insect bites
Can be recurrent or chronic
Presentation of rash due to streptococcal infection?
Most commonly associated with the rah of scarlet fever, which is a fine, erythematous, sandpaper-like rash accentuated at skin creases
Can also cause an urticarial rash
What is erythema multiforme and how does it present?
Acute hypersensitivity syndrome
Associated with a symmetrical rash that starts as dusky red macules and evolves into sharply demarcated wheals and then into target-like lesions
Individual lesions stay fixed for 1-3 weeks
Does not come and go
Presentation of erythema infectiosum (fifth disease)?
Rash starts on face with a slapped-cheek appearance followed by a reticular (lacy) erythematous rash on the trunk and extremities
Presentation of urticaria due to type 1 hypersensitivity?
Classic lesion: intensely pruritic, circumscribed, raised, erythematous wheal, often with central pallor
Lesions may enlarge and coalesce
Lesions continually change, with new lesions occurring as old ones resolve
Usually asymmetric
Individual lesions tend to last only 12-24 hours
Triggers such as drug, food, insect sting, or infection can sometimes be identified
Presentation of erythema migrans?
Red papule at the site of a tick bite, expands to form a large erythematous annular patch
Presentation of drug eruption?
Commonly urticarial
May be type 1 reaction or may result from non-immunologic triggers of mast cell release (such as from opiates or NSAIDs)
Cause of roseola?
HHV-6
How does the rash in roseola spread across the body?
Starts on the trunk, may spread to the face and extremities
Cause of erythema multiforme?
Most commonly caused by HSV infections, but may be associated with medications
Cause of erythema infectiosum (fifth disease)
Parvovirus B19
How does erythema infectiosum spread across the body?
Starts on face, spreads to trunk and extremities
Cause of erythema migrans?
Localized Lyme disease
Describe the rash typically seen in acute urticaria (hives).
A rash that comes and goes, changing almost as one watches
What often causes hives?
Histamine release triggered by allergens like drugs, foods, or pollen
The underlying cause can include viruses and even temperature
What is the atopic triad?
Atopic dermatitis (eczema), asthma, allergic rhinitis (hayfever)
Diagnosis of acute urticaria?
Blood testing to determine specific allergens or refer to allergist for skin scratch testing
Often difficult to determine a cause, testing should be based on severity and frequency
Treatment of acute urticaria?
Avoid suspected allergens
Symptomatic treatment:
1. OTC antihistamines (loratidine, cetirizine, fexofenadine; related to diphenydramine and hydroxyzine but less sedating)
2. Course of oral prednisone is rarely used if antihistamines don’t control symptoms
3. Keep patient cool and calm (cool, soothing baths -> heat will worsen itching)
DDx - Rash in an Infant
- Seborrheic dermatitis (cradle cap)
- Eczema or atopic dermatitis
- Candidal rash
- Psoriasis
Presentation of seborrheic dermatitis?
Common, consists of erythematous plaques with fine to thick greasy yellow scales
Typically seen on the scalp, but may spread to the ears, neck, and diaper area of infants
Common in infants, unusual to have a new case by age 3
Presentation of eczema or atopic dermatitis on scalp?
May involve the posterior scalp
Positive history of atopy
Pruritic, erythematous, dry, scaling plaques on extensor surfaces on other areas of the body
Presentation of candidal rash in infants?
Commonly manifests as a diaper dermatitis
Characterized by an area of erythema in the inguinal region, as well as erythematous papules and plaques with satellite lesions