differential diagnosis

Last reviewed 01/2018

  • patch testing excludes allergic contact dermatitis
  • the greasy yellow appearance of the lesions and their distribution excludes psoriasis, although on the scalp, the differential is more difficult, and rests upon the seborrheic lesions being more diffuse with finer, smaller scales
  • mycological examination of scrapings excludes pityriasis versicolor and may identify Pityrosporum ovale
  • atopic dermatitis - in adults usually appears in antecubital and popliteal fossae
  • candidiasis may resemble genital seborrhoeic dermatitis (1)
  • tinea capitis - direct microscopy and culture helps in diagnosis
  • rosacea - desquamation is not typical; telangiectasias and recurrent oedema may occur
  • erythrasma - well demarcated erythematous patches in the intertriginous areas, characterized by bright coral red fluorescence on illumination with a Wood's lamp
  • rare conditions including SLE, Langerhan's cell histiocytosis and dermatomyositis (2)