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: 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

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)