The nodules are slightly raised above the surrounding skin


#1

A 33 year old woman who recently came from India has a nodular patch on both her
shins which is reddish brown. The nodules are slightly raised above the surrounding
skin. She also has a fever and feels unwell. What is the SINGLE most probable
diagnosis?
A. Lupus vulgaris
B. Erythema nodosum
C. Pyoderma gangrenosum
D. Erythema marginatum
E. Solar keratosis
Erythema nodosum is the most likely diagnosis here. The reason they give a history of
coming from India with fever and feeling of being unwell is to point you towards the
direction of tuberculosis. Erythema nodosum can occur with the primary infection of
TB.
Erythema Multiforme

  • Target lesions
  • If symptoms are severe and
    involve blistering → Think Steven
    Johnson Syndrome
  • Causes:
    o Mycoplasma
    o Penicillin
    Erythema Nodosum
  • Tender, erythematous, nodular
    lesions
  • Usually over shins
  • May also occur elsewhere e.g.
    forearms, thighs
  • Causes:
    o IBD
    o Sarcoidosis
    o Drugs e.g. Penicillins
    Erythema Marginatum
  • Pink rings on torso or inner
    surface of limbs
  • Barely raised and are non-itchy
  • Causes:
    Erythema Chronicum Migrans
  • Target lesions
  • Causes:
    o Only Lyme disease
    Rheumatic fever
    (considered in major
    Jone’s criteria)
    Erythema Infectiosum (fifth disease)
  • Caused by parvovirus B19
  • Childhood infection causing a
    slapped cheek appearance and a
    rash
  • Appears a few days later with
    firm red cheeks
  • Lasts 2 to 4 days, and is followed
    by a pink rash on the limbs and
    occasionally the trunk
    Erythema Ab Igne
  • Reaction caused by chronic
    exposure to infrared radiation in
    the form of heat
  • Usually an elderly who sits too
    close to an open fire or electric
    space heater