Urticaria, photosensitivities, hypersensitivity, vasculitis Flashcards
IgE mediated type 1 hypersensitivity
urticaria
Mast cell is the primary mediator which causes inflammation of mast cells, histamine causes cell contraction with leaking through the cells leading to edema and vasodilation causes erythema
urticaria pathophysiology
Wheals, edematous plaques, with white halos, general distribution, migrate and regess and last <24 hours
urticaria
How to manage acute urticaria?
H1 blockers- cetirizine, levocetirizine, loratidine, then diphenhydramine, hydroxyzine
H2 blockers- famotidine, cimetidine
doxepin- for pruritus
avoid heat, spicy foods, use hypoallergenic products, otc gels for pruritus placed in regrigerator, apply to skin cold, cool bedroom, cool bath, avoid nsaids and alcohol
overheating especially with exercise, itching and burning
cholinergic urticaria
hives after water exposure
aquagenic urticaria
Labwork for urticaria
thyroid
throat culture
punch with DIF
igE immediate hypersensitivity
angioedema
management of patients with non-anaphylaxis angioedema
h1 antihistamines certirizine (high dose) 20mg BID
glucocorticoid; prednisone 20-40mg daily for 7 days
Darier signs
mastocytosis
ingestion or activities that cause mast cell degranulation
nsaid, alcohol ingestion, anticholinergic, anesthetics, narcotics, polymyxin B sulfate
heat & friction
mastocytosis
UVA/UVB mediated
CD4 + T lymphocytes
occurs early in season or with winter tropical vacays
occurs on sun exposed areas primarily the arms, v of chest, back of neck, SPARES THE FACE
papulovesicular, same distribution every time
PMLE
polymorphous light eruption
how to dx and treat PMLE
punch biopsy
prevention with good sunblock and clothing, topical steroids, antihistamine, severe case may need oral steroids
photosensitivity triggered by UV exposure
strong associated wth hep C, liver disease, and hemochromatosis
porphyria cutanea tarda
patient complains of fragility especially hands with ulcers, scarring and milia, hypertrichosis, mottled brown pigment around the eye
PCT
How to dx and manage pct
biopsy w/ DIF
CBC, porphyrins, hepatitis panel
24 HR URINE FOR PORPHYRINS
WOOD LAMP FINDINGS FOR PORPHYRIA CUTANEA TARDA
BRIGHT PINK OR CORAL COLORED URINE
What plants contain psoralen compounds that cause phytophotodermatitis
meadow grass, parsnip, limes, wild angelica, cow parsley, carrot, fig,sweet orance, bishop’s weed, hogweed, rue, and celery
You should always suspect a Fixed Drug Reaction when you see….
well-demarcated hyperpigmented macules on the face (especially around the mouth) hand/fingers, genital
If the patient has been on a medication for _______ it is unlikely the cause of DRESS
more than 3 months
hypersensitivity reaction
often from IV vancomycin
cipro, amphotericin B & rifampin
usually occurs during infusion but may be delayed, extreme flushing and pruritus, angioedema, anaphylaxis
inflammation of blood vessels resulting in narrowed or occluded vessels, severity
vasculitis
non palpable purpura w/ Cayenne pepper appearance (leaky capillaries) Schamburg’s disease
capillaritis or pigmented purpura
Palpable purpura, lesions can coalesce to cover large areas, at times can seem urticarial but lasts > 24 hours, lower extremities and buttocks
leukocytoclastic vasculitis
what should you do if you suspect leukocytoclastic vasculitis
1st- skin biopsy which will reveal- inflammatory infiltrates composed of neutrophils w/ fibrinoid necrosis
Next- if histology confirms- chest xray with lab work
panniculitis
bilateral symmetrical tender pink nodules which can be bruise like, typically on the lower extremities, usually transient but may last 2 years, may have fever and joint pain, occurs with crohns/UC, most common in patient’s with sarcoidosis
erythema nodosum
how to dx erythema nodosum
punch biopsy, must include subcutaeneous fat, CBC, throat culture
how to treat erythema nodosum
1st line- nsaids, indomethacin, naproxen, postassium iodide
2nd line systemic or ILK
compression stockings and elevation
High risk bites
cat bites
bites to hand/foot
puncture/crush injury
immunosuppresion
delayed presentation
proximity to vascular graft/prosthetic joint
how to care for bite wounds:
C/S
then irrigate and debride wound, do not close puncture wounds, do not close a high risk wound
primary closure for a bite only if
bite on the face with concern for cosmesis, antibiotic prophylaxis, f/u in 24-48 hours for wound check, never use tissue adhesive to close wound.
antibiotic choices for bites
prophylaxis 3-5 days
empiric 5-14 days
Treat animal bites with
mupirocin ointment TID
Augmentin 875/125mg BID for 5-14 days
Alternative- PCN & metro, docy and metro, bactrim and metro
update tetanus
assess for need for rabies prophylaxis
how soon should you begin antibiotic therapy after an animal bite
within 8-12 hours of incident
small papules in a cluster or linear pattern, usually found on legs & ankles, children experience urticaria
flea bites
how to treat flea bites?
vacuum regularly, professional exterminator, tcs, burrows solution, antihistamine
20 minutes to 2 hours after painless to sharp sting
Mild redness, urticaria, cyanosis
halo lesion with pale round area surrounded by a ring of erythema, patient may complain of ha, parathesias, n/v, htn, spasms
black widow bite
analgesics, muscle relaxants, antiemetics
tetanus prophylaxis
antivenom safe (risk for anaphylaxis)
intermittent ice application and elevation
min to hours after a painless bite, a central blister, mottled blanched halo with surrounding redness/swelling, becomes necrotic 3-4 days later, severe pruritus and burning pain at bite site w/in 2-6 hours, expanding ulcerative necrosis
brown recluse
tetanus
intermittent ice application and elevation
antibiotic if secondarily infected.
30min to 36 hours after painless bite, a firm nodule with blisters/pus, sloughing may appear, patient will complain of memory impairment, ha, nausea, and fatigue
HOBO
abx if needed
tetanus prophylaxis
intermittent application of ice and elevation
Bee/wasp sting management
cold compress, remove stinger, tcs and antihistamine
Avoid moveing/rubbing limb, fresh water, cold, ice, urination on area, alcohol on site, lemon juice, meat tenderizer if …..
marine sting
what should you do if you acquire a marine sting
remove tentacle, vinegar/seawater/hotwater
antivenom-box jelly
tcs
antihistamine
1st 30 days: flu like symptoms, erythema migrans (bulls eye)
dx and treat
LYME DISEASE
If elisa +- <30 days of symptoms igM and IgG western blot
If elisa -: >30 days just IgG
prophylaxis- doxy 200mg PO, single dose w/in 72 hours of bite
localized doxy 100mg PO BID x 10 days
Amoxicillin 500mg TID x 14days
generalized, intense pruritus, worse at night, erythematous papules, excoriations, burrows/threadlike, fine linear pattern, favors wrists, interdigital spaces, waist, genitalia, areolae and umbilicus, spares head and face.
Scabies
TX with
topical permetrin 5% for infants >2 months and pregnanc
ivermectin 200mcg/kg PO single dose repeat in 1-2 weeks
seal everything in bag for 3 days
treat all household members, itching will persist weeks after treatment
