Urticaria and erythema nodosum Notes

NOTES NOTES URTICARIA & ERYTHEMA NODOSUM GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Vascular reaction of the skin triggered by allergic reaction, irritation, or infection ▪ Vasodilation, increased vascular permeability → fluid leaks into interstitium → swelling/edema ▪ Possible elicitation of hypersensitivity reaction (immune system involved) ▪ Can be acquired (e.g. medications), associated with underlying illness (e.g. malignancies, autoimmune disorders), or have genetic predisposition SIGNS & SYMPTOMS ▪ Range of dermatological manifestations: ▫ Erythema ▫ Swelling ▫ Urticaria, pruritus ▫ Raised or flat lesions DIAGNOSIS ▪ Physical examination ▫ Based on appearance ▪ Patch testing to confirm and determine the allergy ▪ Screening for autoimmune or neoplastic etiologies TREATMENT ▪ Identify/avoid triggers ▪ Address underlying cause ▪ Symptomatic management ERYTHEMA NODOSUM osms.it/erythema-nodosum PATHOLOGY & CAUSES ▪ Acute skin eruption due to inflammation in the subcutaneous adipose tissue ▫ Most common form of acute panniculitis ▪ Chronic or recurrent forms are rare but may occur ▪ Presumably caused by a delayed hypersensitivity type IV reaction to a variety of antigens CAUSES ▪ 30–50% unknown etiology ▪ Infections: Streptococcus spp., M. tuberculosis complex, M. leprae, M. pneumoniae, Yersinia spp., Histoplasma capsulatum, Coccidioides immitis ▪ Autoimmune disorders: inflammatory bowel disease, sarcoidosis, Behçet’s disease, medium-vessel vasculitis ▪ Medications: sulfonamides, oral contraceptives, amiodarone OSMOSIS.ORG 59

▪ Malignancies: hematological malignancies, carcinoid tumours, pancreatic cancer SIGNS & SYMPTOMS ▪ Pre-eruptive phase ▫ Fever, malaise, and arthralgia ▪ Eruptions of red, painful, poorly defined plaques and nodules, most commonly located on shins, knees, arms, thighs, and torso → skin lesions gradually get softer and smaller until they completely disappear over the course of about two weeks DIAGNOSTIC IMAGING Chest X-ray ▪ Additional evaluation to determine the underlying cause TREATMENT MEDICATIONS ▪ Potassium iodide, corticosteroids and colchicine can be used in severe refractory cases OTHER INTERVENTIONS ▪ Address underlying cause ▪ Symptomatic management ▫ Bedrest, leg elevation, compressive bandages, wet dressings, and nonsteroidal anti-inflammatory agents Figure 9.1 A single area of erythema nodosum. DIAGNOSIS ▪ Observation of typical skin lesions LAB RESULTS ▪ Biopsy in uncertain cases ▪ Additional evaluation to determine the underlying cause ▫ Complete blood count, erythrocyte sedimentation rate, antistreptolysin-O titer, throat culture, urinalysis, intradermal tuberculin test, venereal disease research laboratory (VDRL), and cultures, as appropriate 60 OSMOSIS.ORG Figure 9.2 Erythema nodosum affecting the shins; a common site for this disease.

Chapter 9 Urticaria & Erythema HEREDITARY ANGIOEDEMA (HAE) osms.it/hereditary-angioedema PATHOLOGY & CAUSES ▪ Small but important number of all cases of angioedema ▫ Increased vasodilation and vascular permeability → fluid leakage from deep blood vessels → angioedema ▫ Urticaria and pruritus are not present ▪ Attacks begin during childhood and become increasingly frequent and severe ▪ Frequency of attacks differs greatly, varying from weekly episodes to intervals longer than a year; discrepancies can occur among different individuals and at different times in the same individual CAUSES ▪ Inherited in an autosomal dominant manner involving mutation of genes associated with C1-inhibitor (C1INH) that inhibits the complement pathway and is associated with coagulation factor XII ▫ Results in unregulated levels of bradykinin and other vasoactive substances → inflammation, vasodilation, and cellular injury ▫ Attack triggers may include minor trauma, mood and temperature changes, but often no obvious inciting event can be established SIGNS & SYMPTOMS ▪ Recurrent attacks of angioedema ▪ Painless, nonpruritic, nonpitting swelling of extremities, genitalia, buttocks, eyelids, lips, tongue, larynx or gastrointestinal tract ▫ Gastrointestinal tract → nausea, vomiting, intense colicky abdominal pain, diarrhea, dehydration, and intense exhaustion → mimics a surgical emergency and unnecessary surgery could be performed ▫ Larynx → life-threatening airway obstruction → without treatment, death by asphyxia occurs in about 25% ▪ Tightness, tingling, or erythema marginatum corresponding to the affected area may precede the swelling ▪ Each episode usually resolves within 72 hours Figure 9.3 Angioedema of the lips. DIAGNOSIS DIAGNOSTIC IMAGING ▪ Imaging studies may be useful during attacks of gastrointestinal edema LAB RESULTS ▪ Complement testing to assess alterations in the system TREATMENT MEDICATIONS ▪ Management of attacks ▫ Intravenous C1-inhibitor concentrates, kallikrein inhibitors (ecallantide), bradykinin B2 receptor antagonists (icatibant) or, if those are unavailable, fresh-frozen plasma as an alternative OSMOSIS.ORG 61

▪ More than one episode in a month or high risk of developing laryngeal edema → longterm prevention ▫ Danazol (an androgen that increases levels of C4) ▫ C1-inhibitor concentrates OTHER INTERVENTIONS ▪ Avoid specific stimuli that have previously led to attacks ▪ Avoid medications associated with attacks ▫ ACE inhibitors; medications containing estrogen URTICARIA (HIVES) osms.it/urticaria PATHOLOGY & CAUSES ▪ Acute (< six weeks) or, rarely, chronic (> six weeks) skin eruption ▪ Acute form most common dermatologic disorder seen in emergency department ▫ Most often benign and self-limiting, though may rarely progress to lifethreatening angioedema or anaphylactic shock; strong tendency to recur ▪ Hypersensitivity reaction → mast cell degranulation and release of inflammatory mediators → increased vascular permeability → fluid leakage from superficial blood vessels → cutaneous lesion TYPES ▪ Acute urticaria ▫ Single lesions usually last less than 24 hours ▪ Chronic urticaria ▫ May last six weeks or more ▪ Precipitants include psychological and physical stress, cold or hot temperature, pressure or vibration ▪ Physical urticaria is urticaria is induced by an exogenous physical stimulus such as scratching or firm stroking of the skin ▫ The most common type of physical urticaria is called a dermatographism SIGNS & SYMPTOMS ▪ Wheals: skin eruption characterized by itchy, burning or stinging, red, raised plaques with well-defined erythematous margins and pale centers ▫ Individual lesions may coalesce ▫ New lesions may appear as others resolve ▪ Can occur anywhere, but common sites are areas exposed to pressure (e.g., trunk, distal extremities, ears) CAUSES ▪ Assessment for potential causes includes “5 Is” ▫ Infection (bacterial/viral/fungal/parasitic) ▫ Injection of a drug/insect venom ▫ Inhaled substances (pollen, mold, dust) ▫ Ingestion of foods, drugs, chemicals ▫ Internal disease process such as an autoimmune disorder ▪ Vasculitis urticaria associated with autoimmune and malignant diseases 62 OSMOSIS.ORG Figure 9.4 Urticaria of the forearm.

Chapter 9 Urticaria & Erythema DIAGNOSIS ▪ Typically based on appearance ▪ Patch testing to confirm and determine the allergy LAB RESULTS ▪ Complete blood count ▪ Erythrocyte sedimentation rate ▪ Thyroid-stimulating hormone (rule out thyroid disease) ▪ Autoimmune screening TREATMENT ▪ Avoid triggers ▪ Symptomatic management ▫ Antihistamines ▫ In severe cases, corticosteroids or leukotriene inhibitors ▫ Monoclonal antibodies and immunosuppressants may be used in refractory cases OSMOSIS.ORG 63