Dermatology Flashcards
Pemphigus Vulgaris
autoimmune of unclear etiology in which body becomes allergic to owen skin
- antibodies are produced against anigens in the intercellular spaces of epidermal cells
- bullae are within epidermis and are thin and fragile
- painful bullae but not pruritic
Causes of Pemphigus Vulgaris
- Idiopathic
- ACE inhibitors
- Penicillamine
Nikolsky’s sign
easy removal of skin by just a little pressure with the examiner’s finger pulling it off like a sheet
Diseases where Nikolsky’s sign is present
- Pemphigus vulgaris
- Staphylococcus scalded skin syndrome
- Toxic epidermal necrolysis
Pemphigus Vulgaris: Dx
skin biopsy
Pemphigus Vulgaris: Tx
- use glucocorticoids, such as prednisone
- when steroids are ineffective, use the following:
azathiaprine
mycophenolate
cyclophosphamide
Bullous pemphigoid
- can be drug induced by sulfa drugs and others
- fracture of skin is realtively deep and bullae are THICKER WALLED and LESS LIKELY TO RUPTURE
- oral lesions are rare
- less fluid loss and infection less likely
Bullous pemphigoid: dx
- perform a biopsy with immunofluorescent antibodies
Bullous pemphigoid: tx
- Use systemic steroids such as prednisone
- Alternatives to steroids
- tetracycline
- erythomycin with nicotinamide
Pemphigus foliaceus
- associated with other autoimmune diseases
- can be drug induced from ACE inhibitors or NSAIDs
- bullae are more superficial than pemphigus vulgaris
- intact bullae rarely seen because they are so fragile
- no oral lesions
Pemphigus foliaceus: dx and tx
- diagnosed by biopsy and treated with steroids Alternatives to steroids - mycophenolate - cyclophosphamide - azathioprine
Porphyria Cutanea Tarda (PCT)
- disorder of porphyrin metabolism resulting in photosensitivity reaction to an abnormally high accumulaition of porphyrins
Conditions associated with Porphyria Cutanea Tardia
- Alcholism
- Chronic hep C
- Liver disease
- Oral contraceptives
- Liver diease is associated with increased liver iron stores
- Diabetes are found in 25% of these patients
Porphyria Cutanea Tarda: Clinical presentation
- Nonhealing blisters on sun exposed parts of the body such as backs of hands and the face
- Hyperpigmentation of the skin
- Hypertrichosis of the face
Porphyria Cutanea Tarda: Diagnostic Testing
Test for urinary uroporphyrins
- uroporphyrins are elevated 2-5 times above coporyphyrins in this disease
Porphyria Cutanea Tarda: Tx
- Stop drinking alcohol
- Stop all estrogen use
- Use barrier sun protection
- Use phlebotomy to remove Fe. Deferoxamine used to remove Fe
- Chloroquine increases the excretion of porphyrins
Urticaria
- hypersensitive reaction, most often mediated by IgE and mast cell activation, which in EVANESCENT WHEALS AND HIVES
- localized with hypotension and hemodynamically instability
- onset within 30 minutes and last < 24 hrs
- itching is prominent
Causes of urticaria
- Meds (aspirin, NSAIDS, morphine, codene, penicilline, phenytoin)
- Insect bites
- Foods (peanuts, shellfish, tomatoes, and strawberries)
- Emotions
- Contact with latex
Chronic urticaria is associated with the following:
- Pressure on skin (e.g. dermatographism)
- Cold
- Vibration
Severe acute urticaria: tx
H1 antihistamines (e.g. diphenhydramine, hydroxyzine, cyproheptatine
Acute urticaria that is life threatening: tx
H1 antihistamines + systemic steroids
Chronic urticaria tx
Newer antihistamines
- loratadine
- desloratadine
- fexofenadine
- certirizine
If patient develops urticaria due to trigger that can’t be avoided, what’s long term solution?
Desensitization
** make sure to stop B-blockers because they inhibit the epinepherine
Morbilliform rashes
- milder form of urticaria
- typical type of drug reaction
- rash RESEMBLES MEASURES; it is GENERALIZED MACULOPAPULAR ERUPTION THAT BLANCHES WITH PRESSURE
- can appear a few days after initial exposure
Morbilliform rashes: dx and tx
- Lymphocyte mediated
- teat with antihistamines
Erythema Multiform Causes
- caused by: penicillins phenytoins NSAIDS Sulfa drus Infection with Herpes Simplex or Mycoplasma
Erythema Multiforme
- presents with TARGETLIKE LESION that occurs on palms and soles
- lesions can be described as “irislike”
- bullae not unformly found
- does not involve mucous membranes
Erythema Multiforme: Tx
Antihistamines and treat the underlying infection
Stevens-Johnson Syndrome
- hypersensitivity rxn to meds (e.g. penicillins, sulfa drugs, NSAIDS, phenytoin, and phenobarbitol)
- usually involves 10 - 15 % of total body surface area
- has mucous membrane involvement
- respiratory tract involvement may be so severe as to require mechanical ventilation
- should be managed in burn unit
Mortality and morbidity associated with Stevens-Johnson Syndrome
- infection, dehydration, and malnutrition
Stevens-Johnson Syndrome: Tx
Supportive therapy
Toxic Epidermal Necrolysis
- most serious version of cutaneous hypersensitivt reaction
- covers 30 - 100% of body surface area
- sepsis is most common cause
- Nikolsky sign is present and skin easily sloughs off
Toxic Epidermal Necrolysis: Dx
Skin biopsy
** don’t use steroids
Fixed Drug Reaction
- localized allergic drug reaction that occurs at precisely the same anatomic site with repeated drug exposure
- lesions are ROUND, SHARPLY DEMARCATD LESIONS THAT LEAVE HYPERPIGMENTED SPOT AT THE SITE
Fixed Drug Rxn: Tx
Topical steroids
Erythema Nodosum
- painful, red, raised nodules appear on anterior surface of extremities
- nodules are tender to palpation
- nodules do not ulcerate
- nodules last about 6 weeks
Erythema Nodosum associated with which conditions:
secondary to recent infections or inlammatory condtiions such as: - Pregnancy - Recent strep infxn - Coccidiodomycoses - Histoplasmosis - Sarcoidosis = Inflammatory bowel disease - Syphilis - Hepatitis - Enteric infection (e.g. Yersinia)
Erythema Nodosum: Tx
- Analgesics and NSAIDS and treat the underlying disease
- if symptomatic treatment fails, potassium iodide
Suspected fungal infxn : diagnostis - tinea pedis - tinea cruris - tinea corporis - tinea versiclor - tinea capris -
- Perform KOHtest of skin. KOH can dissolve some epithelail cells and collage of the nail but doesn’t melt away fungus
- Most accurate test: culture of fungus
Onychomycosis (nail fungal infection) : tx
Oral terbinafine or itraconazole
- 6 weeks for fingernails
- 12 weeks for toes
Hair fungal infection (tinea capitus)
Oral terbinafine or itraconazole
Terbinafine
- used to treat skin and hair fungal infections
- potentially hepatotoxic
- check liver function tests periodically
Adverse effects of ketaconazole
- Hepatotoxicity
- Gynecomastia
- don’t use for onychomycosis**
Impetigo
- special bacterilal infection of skin limited to largely epidermis
- infection is described as “weeping” “oozing” “honey-colored” or draining”
- found in warm, humid conditions
- seen in poverty and in children
- can cause glomerulonephritis but no rheumatic fever
Impetigo: etilogy
Staphylococcus
- can be caused by Streptococcus pyogenes (aka Group A Strep_)
Impetigo: Tx
- Any topical abx: mupirocin
- If topical abx not effective, antistaphyloccocus oral abx
Erysipelas
- involves both dermis and epiderms
- most commonly caused by Group A Strep (pyogenes)
- most likely bacterial infxn to lead to fevers, chills, and bacteremia
- bright, red, angry, swollen appearance in face
Erysipelas: tx
= use systemic oral or IV abx
- if there is culture confirmation of the organism as Streptococcus then penicillin G or ampicillin
Cellulitis
- bacterial infection of dermis and subcutaneous with Stap and Strep
