POM II - Allergic + Inflammatory Rxn - Exam 1

Type I Hypersensitivity - Allergic

-immediate reaction: lesions arise in seconds to hours and resolves within 24 hours

-urticaria: transient, edematous, red papules and plaques

-angioedema

Acute Urticaria

-eruption lasting <6 weeks

-etiology: often idiopathic (50%)

-40% URI; 9% drugs

-IgE mediated/Histamine driven

-Prognosis - excellent if no re-exposure

Chronic urticaria

-eruption lasting 6+ weeks

-more treatment resistant more aggressive course

-probable IgG1 or IgG3 subclass, anti-IgE antibody

-idiopathic > physical > autoimmune

Urticaria

-erythematous, edematous papules or wheals that develop on the skin in response to stimuli

-hives form in response to histamine when blood plasma leaks out of small blood vessels into the skin

-#1 symptom is pruritus

-hallmark: lesions last less than 24 hours

Allergic Urticaria

-food

-environmental

-pets

-inhalants

Chemical urticaria

-drug-induced: NSAIDs, abx common

-stress-induced

Physical Urticaria

-symptomatic dermatographism - mc type of physical

-cold urticaria

-cholinergic

-adrenergic

-contact

-delayed pressure

-solar

-vibratory

-aquagenic

Chronic Urticaria - 5 Is

-ingestants (most common)

-inhalants: dust, feather, pollen

-injectants: drugs, stings, bites

-Infections

-internal disease

Urticaria - Hx

-when did it start?

-recent illness

-meds

-travel

-assoc symptoms

-fmhx

-exacerbating factors

-rash that itches or itch that rashes

Urticaria - Tx

-2nd gen antihistamines first line (Certizine, Loratadine, Fexofenadine)

-1st gen antihistamines

-H2 blockers

-leukotriene inhibitors

Angioedema

-histologically deeper variant of urticaria - dermal and subcutaneous swelling

-more diffuse swelling, less pruritus than urticaria

-Mc affected areas include lips, palms, soles, limbs, trunk, and genitals

-rarely, angioedema of the throat, tongue, or lungs can block airway

Mast Cell-mediated Angioedema

-associated sx include urticaria, flushing, pruritus, bronchospasm

-begins within minutes of exposure, builds in hours, resolves in 1-2 days

Bradykinin-Induced Angioedema

-no other symptoms

-prolonged course (develops over 24-36 hours, resolves in 4+ days)

-difficult to determine trigger

Angioedema - Tx

-if cause identified, d/c

-laryngeal swelling -- emergent epinephrine

-other long term management --> cyclosporine, omalizumab

Behcet's Syndrome

-recurrent painful oral aphthous ulcers with other systemic manifestations

-vasculitis involving all types of blood vessels

-autoimmune/autoinflammatory

-genetic link

-clinical dx

Behcet's Syndrome Incidence

-Turkey (up to 420 cases per 100,000) but more rare in the US

-young adults

Behcet's Syndrome - Tx

-symptom management (steroids, sucralfate)

-lesion treatment/prevention (colchicine)

-immunologics for severe disease

Erythema Multiforme

-type IV hypersensitivity reaction usually triggered by infections, most commonly HSV

-HSV 1 > HSV2, young males usually

-clinical dx

-minor: mild or no mucosal involvement

-major: mucosal involvement

-usually acute and self-limited

Erythema Multiforme - Lesion

-sharp margin, regular round shape, three concentric color zone

-center: dark red with blister or crust

-2nd ring: paler pink, raised due to edema

-outermost ring: bright red

Erythema Multiforme Major

-same lesions as EM-minor + mucosal involvement

-can affect eyes, anus, genital, and GI tract

-oral mucosa is most affected (lips, inside cheeks, tongue)

Erythema Multiforme - Tx

-treat primary infxn

-supportive: antihistamine, topical CCS, mouth washes

-recurrent: continuous oral acyclovir or valacyclovir for 6 months

-usually resolves w/o scarring over 2 weeks to 1 month

Erythema Nodosum

-painful nodules without ulceration on anterior lower legs

-lasts 6 weeks, can recur; may be preceded by fever, malaise, arthralgia

-incidence: women 10x more than men

Erythema Nodosum - Etiology

-idiopathic

-infection

-sarcoidosis

-IBD

-Pregnancy

-OCPs

Erythema Nodosum - Tx

-NSAIDs and elevation for pain and swelling

-corticosteroids, dapsone, colchicine, hydroxychloroquine

Graft vs Host Disease

-donated bone marrow or stem cells view recipient's body as foreign and attack it

-rash: raised or discolored thickening or tightening of skin; burning sensation; palms/soles of feet, often on trunk and extremities

-can also present with hepatic or GI sx

GHD incidence

1/3 to 2/3 of all allogeneic transplant recipients

GHD prognosis

can be fatal if untreated, resolves within 5 years with treatment

GHD - tx

-depends on affected body system and symptom severity

-immunosuppressants, steroids

Hypersensitivity Vasculitis

-predominantly small vessel disease without systemic vasculitis

-palpable purpura on lower extremities

-induration, necrosis, ulceration, ecchymosis, haloing, and confluence can occur

-benign, undetermined origin

Hypersensitivity Vasculitis

-incidence: 38-55 per million, equal about gender and ages

-prognosis good, but may decrease if systemic disease present

-dx: skin biopsy, further workup if suspect systemic vasculitis or underlying disease

Hypersensitivity Vasculitis - Tx

-identify and control triggers, compression stockings, elevation, bed rest

-topical or oral steroids, colchicine, dapsone, immunosuppressants may be considered

Anaphylaxis

-severe, life-threatening allergic rxn within seconds to minutes of exposure

-sx: skin rxn, hypotension, airway constriction, NVD, dizziness/fainting

-mc drugs: NSAIDs, beta lactams (amoxicillin)

Drug-Induced Hypersensitivity Syndrome

-rare, autoimmune

-ranges from mild pruritus to life-threatening skin/mucosal loss

-blanket term for SJS, TEN, DRESS, Drug-induced lupus

-usually 1-3 weeks after first ingestion of meds

Epidermal Necrolysis

-extensive necrosis and detachment of the epidermis (sloughing)

-mucous membrane involvement

SJS

if a patient has <10% of their body surface area involved, do they have SJS or TEN?

TEN

if a patient has >30% of their body surface area involved, do they have SJS or TEN?

Stevens Johnson Syndrome

-severe immune-mediated cutaneous drug reaction

-<10% BSA epidermal detachment

-prominent mucosal involvement

-prodrome: fever, malaise, ST, then painful rash

-common triggers: sulfonamides, anticonvulsants, allopurinol

-treat like burn patient

Toxic Epidermal Necrolysis

-same disease as SJS, but more extensive

-most commonly drug-induced: sulfonamides, allopurinol

->30% BSA epidermal detachment

-positive Nikolsky sign

-burn unit or ICU, 30-50% mortality

TEN tx

-outcome depends on quality of care and rapidity with which tx is initiated

-stop offending drug

-admission to burn unit/supportive care

-IVIG 0.2 g/kg/day to 2 g/kg/day for 1-5 days

Sunburn

-genetic component

-prevention!!!

-can affect all skin tones

-risk factor for skin cancer

-mild erythema --> highly painful erythema with edema, vesiculation, blistering

Sunburn - Tx

-OTC calamine lotion, aloe

-cool compresses

-NSAIDs

-mild soap/water

Drug-Induced Photosensitivity

-considered an adverse drug reaction

-common offenders: tetracyclines, HCTZ, sulfonamides, metformin, FQs, NSAIDs, amiodarone, retinoids

-onset within minutes to hours of sun exposure, limited to exposed skin

-vesicles or bullae may form, UVA radiation

Drug-Induced Photosensitivity - Tx

-DC offending agent if possible

-sun protection

-treat as sunburn

Solar Lentigo

-well-circumscribed 1- to 3-cm brown macules

-localized proliferation of melanocytes and accumulation of melanin due to chronic sun exposure

-eval for suspicion of malignancy

Solar Lentigo - tx

-cryotherapy

-laser

-minimize sun exposure

-sunscreen

Dermatoheliosis

-skin changes induced by chronic UVA and UVB exposure

-aka photoaging

-can be prevented by sunscreen, protective outerwear

-if present, monitor for skin cancer

-tretinoin is best treatment

Immunobullous Disease

-caused by associated with specific autoantibodies that bind to epithelium resulting in tissue separation/blistering

-pemphigus, bullous pemphigoid, linear IgA disease, dermatitis herpetiformis

Pemphigus Vulgaris

-rare autoimmune blistering d/o of skin and mucous membranes

-fragile bullae, rupture easily

-etiology: DRUGS, systemic malignancy, and trauma

Pemphigus Vulgaris - Dx

-direct (punch biopsy)

-indirect (serum)

-immunofluorescence

Pemphigus Vulgaris - Tx

-d/c offending drug

-corticosteroids/immunosuppressants

Bullous Pemphigoid

-autoimmune blistering d/o

-presents as intact tense blisters/bullae

-type II hypersensitivity rxn

-rarely affects mucosal skin, most common older pts

Bullous Pemphigoid - Biopsy

shave for hematoxylin and eosin stain + punch for direct immunofluorescene

Bullous Pemphigoid - Tx

-topical steroids

-systemic prednisone or steroid sparing immunosuppressants

-antibiotics (tetracyclines or erythromycin)

Dermatitis Herpetiformis

-autoimmune from gluten sensitivity

-associated with celiac, avg age 30s-40s

-subepidermal deposition of IgA and neutrophilic dermal infiltrates in superficial dermis

-very pruritic inflammatory papules and vesicles on forearms, knees, scalp, buttocks

-eliminate dietary gluten, dapsone

Linear IgA Disease

-rare autoimmune blistering disease

-idiopathic or drug induced

-IgA antibodies bound to basement membrane zone

-humoral and cellular immune responses involved

-skin and/or mucosal membrane lesions: tense pemphigus-like vesicles and bullae

-tx: dapsone and topical corticosteroids