Approach to a Rash 2018-01-30T16:36:30+00:00

Erythema Nodosum

Characteristics

  • Painful, symmetrical red nodules
  • Usually 1 – 10 cm in size
  • Most often on anterior legs
  • Involutes in weeks, giving a bruise-like appearance
  • New lesions may occur over up to eight weeks
  • Does not ulcerate, tends to heal completely
  • May have prodromal illness
    • Malaise
    • Fever
    • Arthralgia
  • Histology: septal panniculitis

Differential diagnosis

  • Infective
    • Streptococcal pharyngitis
    • Tuberculosis
    • Hepatitis B and C
    • Epstein-Barr virus
    • Human immunodeficiency virus
    • Whipple’s disease
    • Gastroenteritis secondary to bacterial infection
    • Histoplasmosis
    • Syphilis
  • Inflammatory
    • Sarcoidosis (Löfgren’s syndrome – acute sarcoidosis with EN, bilateral hilar lymph nodes, arthritis)
    • Inflammatory bowel disease
    • Behcet’s syndrome
  • Malignancy
    • Hodgkin’s lymphoma
  • Drugs
    • Antibiotics
      • Sulphonamides
      • Amoxicillin
    • Oral contraceptive pill
    • Montelukast
  • Neoplastic
    • Lymphoma
  • Pregnancy
  • Idiopathic (up to 55%)

Investigations

  • Confirm diagnosis: biopsy of skin lesion
  • Full blood count to look for evidence of infection, differential to screen for lymphoproliferative disease
  • Liver function tests (hepatitis B and C)
  • Human immunodeficiency virus test
  • Chest radiograph
    • Bilateral hilar lymphadenopathy (sarcoidosis)
    • Apical consolidation (tuberculosis)
  • Sputum for acid-fast bacilli stain and culture, molecular detection of mycobacterium tuberculosis
  • Consider colonoscopy to evaluate for ulcerative colitis
  • Consider pharyngeal swab for Group A Streptococci, anti-streptolysin-O titre
  • Consider stool culture for gastrointestinal organisms

Management

  • Multidisciplinary team approach
  • Patient education: tends to be self-limiting
  • Consider referral to Dermatology
  • Analgesia: paracetamol, non-steroidal anti-inflammatory drugs
  • Treat underlying cause
  • If severely symptomatic, consider oral potassium iodide 400 – 900mg / day (most likely to be effective if started early)
    • Monitor thyroid function closely
  • May also consider prednisolone 1mg/kg/day if very symptomatic
Credit: <a href=https://commons.wikimedia.org/wiki/User:Jmh649>James Heilman, MD</a href>
Credit: James Heilman, MD

Erythema Multiforme

Characteristics

  • Acute
  • Immune-mediated
  • Lesions may have mucosal involvement
  • Acrally distributed papules surrounded by erythema
  • Distinct, target lesions
  • Concentric colour changes
  • Usually self-limiting, but may be recurrent
  • Recent consensus classification:
    • Distinct from Stevens-Johnson syndrome

Differential diagnosis

  • Infections
    • Herpes simplex virus (usually type 1)
    • Mycoplasma pneumoniae
    • Hepatitis C
    • Epstein-Barr virus
  • Drugs
    • Sulphonamides (Bactrim)
    • Sulphonylureas
    • Anti-epileptics
    • Antibiotics
    • Non-steroidal anti-inflammatory drugs
    • Allopurinol
  • Inflammatory
    • Inflammatory bowel disease
    • Graft versus host disease
    • Polyarteritis nodosa
    • Sarcoidosis
  • Malignancy (leukaemia and lymphoma)

Investigation

  • HSV PCR from suspicious skin lesions
  • Full blood count
  • Liver function tests (hepatitis C)
  • Chest radiograph (Mycoplasma, sarcoidosis)
  • Consider serological test for Mycoplasma
  • Consider colonoscopy (inflammatory bowel disease)
  • Consider skin biopsy
  • Consider age-appropriate malignancy screening

Management

  • Patient education
  • Stop offending drug, if any
  • Treat underlying disease
  • Symptomatic treatment: antihistamines for pruritus
  • Consider topical corticosteroids if symptomatic
  • Consider antiviral prophylaxis or dapsone for recurrent EM
Credit: James Heilman, MD

Livedo Reticularis

Characteristics

  • Increased visibility of venous plexuses
  • May be caused by
    • Deoxygenation
      • Decreased flow
      • Increased viscosity
      • Increased venous resistance
      • Venous thrombosis
    • Venodilation
      • Local hypoxia
      • Dysautonomia
  • Mottled, reticulated vascular pattern
  • Lace-like purplish discolouration of skin

Differential diagnosis

  • Inflammatory
    • Anti-phospholipid syndrome
    • Systemic lupus erythematosus
    • Sneddon’s syndrome (LR + cerebrovascular lesions)
  • Hyperviscosity
    • Cryoglobulinaemia (may be secondary to hepatitis C)
    • Cold agglutinin disease (may be secondary to Mycoplasma infection)
    • Polycythaemia vera
    • Essential thrombocytosis
    • Acute leukaemia
    • Chronic lymphocytic leukaemia
    • Waldenström’s macroglobulinaemia
  • Embolic disease
    • Cholesterol embolisation syndrome
    • Septic emboli
  • Hypercoagulable states
    • Anti-thombin III deficiency (may be secondary to nephrotic syndrome)
    • Protein C deficiency
    • Protein S deficiency
  • Drugs
    • Amantadine
    • Minocycline
    • Gemcitabine
    • Warfarin (skin necrosis)
  • Calciphylaxis (may be secondary to chronic kidney disease)
  • Congenital
    • Cutis marmorata telangiectasia congenita
    • Ehlers-Danlos syndrome

Relevant points in the history

  • Anti-phospholipid syndrome
    • Have you ever had blood clots in your legs or lungs?
    • Have you ever had a stroke?
    • Have you ever had a heart attack?
    • Have you ever had any miscarriages?
  • Systemic lupus erythematosus
    • Have you lost any hair?
    • Do you have any mouth ulcers?
    • Do you get any joint pains?
    • Have you ever had a rash on your face?
  • Hepatitis C
    • Have you ever had a blood transfusion?
    • Have you ever injected drugs through a vein?
    • Have you ever noticed episodes where your skin or eyes have appeared yellow?
    • Have you noticed a rash on your chest or face?

Investigations

  • Full blood count (anaemia of chronic disease, myeloproliferative disease)
  • Auto-antibodies
    • Anti-phospholipid syndrome
      • Anti-cardiolipin (IgG and IgM)
      • Anti-β2 glycoprotein (IgG and IgM)
      • Lupus anticoagulant
    • Systemic lupus erythematosus
      • Anti-nuclear
      • Anti-double stranded DNA
    • Renal function
    • Calcium (calciphylaxis)
    • May consider skin biopsy if diagnosis uncertain

Management

  • Consider low-dose aspirin if patient asymptomatic
  • If previous thrombosis: consider anticoagulation (lifelong)
  • Treat the underlying cause

Easy Bruising

Differential diagnosis

  • Cushing’s syndrome
  • Henoch-Schonlein purpura
  • Connective tissue disease
    • Marfan’s syndrome
    • Ehlers-Danlos syndrome
  • Platelet abnormalities
    • Immune thrombocytopaenic purpura
    • von Willebrand’s disease
  • Coagulopathy
    • Chronic liver disease
    • Vitamin K deficiency
    • Congenital haemophilia
    • Acquired haemophilia
    • Acute promyeloid leukaemia

Hypopigmentation

Differential diagnosis

  • Vitiligo
  • Tinea vesicolour
  • Ash leaf spots (tuberous sclerosis)
  • Leprosy
  • Sarcoidosis
  • Cutaneous T cell lymphoma
  • Depigmentation associated with underlying melanoma

Characteristics of vitiligo

  • Acquired depigmentation of the skin
  • Autoimmune process directed at melanocytes
  • Onset usually in second and third decade
  • Usual distribution is acral
  • May display Koebner phenomenon
  • Usually slowly progressive
  • 10 – 20% may experience spontaneous re-pigmentation

Associated autoimmune disorders

  • Hyperthyroidism (Graves’)
  • Hypothyroidism (Hashimoto’s)
  • Addison’s disease
  • Pernicious anaemia
  • Systemic lupus erythematosus
  • Psoriasis
  • Rheumatoid arthritis
  • Inflammatory bowel disease
  • Autoimmune polyglandular syndrome type II
    • Autoimmune thyroid disorders
    • Type I diabetes mellitus
    • Hypopituitarism
    • Primary adrenal insufficiency

Examination

  • Vitals, including postural blood pressure
  • Thyroid status
    • Tremor
    • Pulse
    • Coarse facies
    • Coarse hair
    • Hoarse voice
    • Goitre
    • Proximal myopathy
    • Pretibial myxoedema
  • Examination of skin
    • Psoriasis – especially nails, elbows, scalp, retro-auricular
    • Melanoma
  • Inflammatory disorders
    • GALS screen
    • Rheumatoid nodules
    • Mouth ulcers
  • Ideally: examine vitiligo under Wood’s lamp to differentiate depigmentation from lightly-pigmented skin

Investigations

  • Consider fasting plasma glucose
  • Consider thyroid function tests
  • Consider anterior pituitary hormone screen
  • Consider short synACTHen tests

Management

  • Sunscreen to minimize tanning and contrast between normal skin and depigmented skin
  • Makeup (e.g. Dermablend) to camouflage depigmented areas
  • Topical corticosteroids (moderate quality evidence for short-term benefit)
  • Ultraviolet therapy (moderate evidence)
Credit: Produnis

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This Sliding Bar can be switched on or off in theme options, and can take any widget you throw at it or even fill it with your custom HTML Code. Its perfect for grabbing the attention of your viewers. Choose between 1, 2, 3 or 4 columns, set the background color, widget divider color, activate transparency, a top border or fully disable it on desktop and mobile.