Updated: 2/21/2019

Psoriasis

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Snapshot
  • A 42-year-old man presents to his dermatologist for management of his psoriasis. He reports an itchy and rough rash along his elbows, knees, and scalp. While he was previously treated for this disease in childhood, he has been off treatment for years. Physical exam reveals 2-7 cm pink plaques with overlying silvery scales. When the scale is scratched off, there is pinpoint bleeding. He is started on an intensive topical therapy regimen with corticosteroids and vitamin D analog.
Introduction
  • Clinical definition
    • idiopathic and chronic inflammatory disease characterized by silver scales and thickened skin
      • most common subtype is plaque psoriasis
  • Epidemiology
    • incidence
      • US incidence
        • 2% of population
    • demographics
      • normallly, > 40 years of age but can affect people of all ages
    • risk factors
      • smoking
      • skin trauma
      • alcohol abuse
      • stress
      • cold weather
  • Etiology
    • idiopathic
    • drugs
  • Pathogenesis
    • hyperproliferation of basal stem keratinocytes
    • ↑ inflammation, especially inflammatory markers IL-6, C-reactive protein, TNF-α, E-selectin, ICAM-1
  • Associated conditions
    • psoriatic arthritis  
Presentation
  • Symptoms
    • painful or pruritic skin lesions
    • joints may be painful or stiffens
      • especially in feet and hands
  • Physical exam
    • well-circumscribed, pink papules and flat-topped plaques with silvery scales
    • common locations
      • scalp
      • trunk
      • buttocks
      • extensor surface of limbs
    • positive Auspitz sign
      • when scales are scraped off, there is pinpoint bleeding
        • results from exposure of dermal papillae
    • nail pitting
Studies
  • Labs
    • electrolytes
      • there may be electrolyte imbalances if psoriasis is extensive
  • Histology
    • acanthosis with parakeratosis (thickened stratum corneum with retained nuclei)
    • Munro microabscesses
    • ↑ stratum spinosum
    • ↓ stratum granulosum
Differential
  • Atopic dermatitis
  • Seborrheic dermatitis
Treatment
  • Conservative
    • emollients
      • indication
        • for all patients
  • Medical
    • topical corticosteroids
      • indication
        • first-line and often used in combination with topical calcipotriene
    • topical calcipotriene (vitamin D analog)
      • indication
        • first-line and often used in combination with topical corticosteroids
    • systemic non-biologic therapies
      • indication
        • moderate-to-severe psoriasis
        • used in combination with topical therapies
      • drugs
        • acitretin
        • methotrexate
        • cyclosporine
        • apremilast
          • especially for those with psoriatic arthritis as well
    • systemic biologic therapy
      • indication
        • moderate-to-severe psoriasis
      • drugs
        • tumor necrosis factor inhibitors
          • adalimumab
          • etanercept
          • infliximab
        • anti-interleukin agents
          • secukinumab
          • ustekinumab
    • narrowband ultraviolet B
      • indications
        • for patients who are contraindicated to systemic therapy
Complications
  • Psoriatic arthritis
  • Other HLA-B27 associated autoimmune diseases
 

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Questions (3)
Lab Values
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/L
Female: 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/mL
Female: 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/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative 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/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 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/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 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/min
Female: 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 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 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
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