Snapshot A 25-year-old man presents with an itchy rash on his chest wall. He denies any exposures to insects and denies any previous allergies. He recently had an upper respiratory infection. Physical exam shows blanching, raised, edematous annular lesions that are well-circumscribed. Some lesions are coalesced. This is his first episode of this itchy rash. He denies any other symptoms. Introduction Pruritic inflammation of the skin commonly known as “hives” Characterized by superficial, localized edema and erythema Epidemiology most frequent dermatologic disorder seen in the emergency room Pathogenesis involving dermis and epidermis mast cell and basophil release of vasoactive substances histamine, bradykinin, and prostaglandins intense pruritus is from histamine in the dermis type I hypersensitivity reaction Triggers of acute urticarial (< 6 weeks) drugs food viral infection recent illness insect bite emotional stress cold or heat alcohol ingestion pregnancy exposure to other allergens (pet dander, dust, mold, or chemicals) sun Chronic urticarial is usually idiopathic (> 6 weeks) Etiology identified in 40-60% of acute cases and 10-20% in chronic cases Presentation Symptoms history of previous urticaria pruritus lasts a few hours resolves spontaneously Physical exam well-circumscribed erythema and edema on skin blanching, raised, and palpable wheals can occur on anywhere on the body dermotographism (urticaria from light scratching) indicates very sensitive skin Evaluation Labs or biopsy not indicated for acute urticarial unless diagnosis is unclear ↑ IgE For chronic or recurrent urticarial test ESR, TSH, and ANA Histology of lesion dermal edema lymphatic channel dilation Differential Diagnosis Hereditary angioedema Contact dermatitis Multiple insect bites Erythema multiforme Treatment If known, discontinue offending agent If concern for airway compromise epinephrine Anti-histamines second generation > first generation Prognosis, Prevention, and Complications Prognosis most resolve spontaneously Prevention avoid known triggers take second generation anti-histamine daily Complications life-threatening angioedema
QUESTIONS 1 of 3 1 2 3 Previous Next Lab Values Blood Hematologic Cerebrospinal Sweat, Urine, and BMI Blood, Plasma, Serum Reference Range ALT 8-20 U/L Amylase, serum 25-125 U/L AST 8-20 U/L Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL Calcium, serum (Ca2+) 8.4-10.2 mg/dL Cholesterol, serum Rec: < 200 mg/dL Cortisol, serum 0800 h: 5-23 μg/dL //1600 h: 3-15 μg/dL 2000 h: ≤ 50% of 0800 h Creatine kinase, serum Male: 25-90 U/LFemale: 10-70 U/L Creatinine, serum 0.6-1.2 mg/dL Electrolytes, serum Sodium (Na+) 136-145 mEq/L Chloride (Cl-) 95-105 mEq/L Potassium (K+) 3.5-5.0 mEq/L Bicarbonate (HCO3-) 22-28 mEq/L Magnesium (Mg2+) 1.5-2.0 mEq/L Estriol, total, serum (in pregnancy) 24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL 28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL Ferritin, serum Male: 15-200 ng/mLFemale: 12-150 ng/mL Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL Female: premenopause: 4-30 mIU/mL midcycle peak: 10-90 mIU/mL postmenopause: 40-250 pH 7.35-7.45 PCO2 33-45 mmHg PO2 75-105 mmHg Glucose, serum Fasting: 70-110 mg/dL2-h postprandial:<120 mg/dL Growth hormone - arginine stimulation Fasting: <5 ng/mLProvocative stimuli: > 7ng/mL Immunoglobulins, serum IgA 76-390 mg/dL IgE 0-380 IU/mL IgG 650-1500 mg/dL IgM 40-345 mg/dL Iron 50-170 μg/dL Lactate dehydrogenase, serum 45-90 U/L Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL Female: follicular phase: 5-30 mIU/mL midcycle: 75-150 mIU/mL postmenopause 30-200 mIU/mL Osmolality, serum 275-295 mOsmol/kd H2O Parathyroid hormone, serume, N-terminal 230-630 pg/mL Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L Phosphorus (inorganic), serum 3.0-4.5 mg/dL Prolactin, serum (hPRL) < 20 ng/mL Proteins, serum Total (recumbent) 6.0-7.8 g/dL Albumin 3.5-5.5 g/dL Globulin 2.3-3.5 g/dL Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h Thyroxine (T4), serum 5-12 μg/dL Triglycerides, serum 35-160 mg/dL Triiodothyronine (T3), serum (RIA) 115-190 ng/dL Triiodothyronine (T3) resin uptake 25%-35% Urea nitrogen, serum 7-18 mg/dL Uric acid, serum 3.0-8.2 mg/dL Hematologic Reference Range Bleeding time 2-7 minutes Erythrocyte count Male: 4.3-5.9 million/mm3Female: 3.5-5.5 million mm3 Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/hFemale: 0-20 mm/h Hematocrit Male: 41%-53%Female: 36%-46% Hemoglobin A1c ≤ 6 % Hemoglobin, blood Male: 13.5-17.5 g/dLFemale: 12.0-16.0 g/dL Hemoglobin, plasma 1-4 mg/dL Leukocyte count and differential Leukocyte count 4,500-11,000/mm3 Segmented neutrophils 54%-62% Bands 3%-5% Eosinophils 1%-3% Basophils 0%-0.75% Lymphocytes 25%-33% Monocytes 3%-7% Mean corpuscular hemoglobin 25.4-34.6 pg/cell Mean corpuscular hemoglobin concentration 31%-36% Hb/cell Mean corpuscular volume 80-100 μm3 Partial thromboplastin time (activated) 25-40 seconds Platelet count 150,000-400,000/mm3 Prothrombin time 11-15 seconds Reticulocyte count 0.5%-1.5% of red cells Thrombin time < 2 seconds deviation from control Volume Plasma Male: 25-43 mL/kgFemale: 28-45 mL/kg Red cell Male: 20-36 mL/kgFemale: 19-31 mL/kg Cerebrospinal Fluid Reference Range Cell count 0-5/mm3 Chloride 118-132 mEq/L Gamma globulin 3%-12% total proteins Glucose 40-70 mg/dL Pressure 70-180 mm H2O Proteins, total < 40 mg/dL Sweat Reference Range Chloride 0-35 mmol/L Urine Calcium 100-300 mg/24 h Chloride Varies with intake Creatinine clearance Male: 97-137 mL/minFemale: 88-128 mL/min Estriol, total (in pregnancy) 30 wks 6-18 mg/24 h 35 wks 9-28 mg/24 h 40 wks 13-42 mg/24 h 17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 hFemale: 2.0-8.0 mg/24 h 17-Ketosteroids, total Male: 8-20 mg/24 hFemale: 6-15 mg/24 h Osmolality 50-1400 mOsmol/kg H2O Oxalate 8-40 μg/mL Potassium Varies with diet Proteins, total < 150 mg/24 h Sodium Varies with diet Uric acid Varies with diet Body Mass Index (BMI) Adult: 19-25 kg/m2 Calculator ( ) xy AC 7 8 9 ÷ 4 5 6 × 1 2 3 - 0 . = + Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.MK.28) A 35-year-old woman comes to see her primary care physician, because she is concerned about her skin. She states that she noticed a rash after recently starting a new medication. The rash appears as numerous pale, red, raised, itchy bumps on both of her legs, as seen in Figure A. What histologic pattern is most consistent with this patient's dermatologic condition? Review Topic QID: 103821 FIGURES: A 1 Dermal edema 57% (65/115) 2 Spongiosis 31% (36/115) 3 Hyperkeratosis 6% (7/115) 4 Acantholysis 0% (0/115) 5 Acanthosis 5% (6/115) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 1 (M1.MK.1) A 17-year-old female accidentally eats a granola bar manufactured on equipment that processes peanuts. She develops type I hypersensitivity-mediated histamine release, resulting in pruritic wheals on the skin. Which of the following layers of this patient's skin would demonstrate histologic changes on biopsy of her lesions? Review Topic QID: 101309 1 Stratum corneum 18% (37/201) 2 Stratum granulosum 16% (32/201) 3 Stratum spinosum 12% (25/201) 4 Stratum basale 9% (18/201) 5 Dermis 43% (87/201) M1 Select Answer to see Preferred Response PREFERRED RESPONSE 5