Differential diagnosis festival: fever + rash and tender cervical lymphadenopathy

Fever + Rash

Two big picture points for thinking about ddx

  • For some reason I always thought this ddx was short. It’s super long and interesting!
  • Organize ddx based on whether the patient is immunocompetent or immunocompromised and specifically whether they have HIV

Ddx for immunocompetent patients (asterisks indicate life-threatening “Can’t miss” diagnoses)

  • Infectious
    • Bacterial
      • Toxic shock*
      • Meningococcemia*
      • Necrotizing fasciitis*
      • Bacterial endocarditis*
      • Scarlet fever
      • Depending on exposure: Rocky Mountain Spotted fever*, tularemia,* lyme disease, ehrlichiosis,* relapsing fever, vibrio vulnificus* and parahemalyticus*, Typhoid fever, dengue fever* chikungunya
    • Viral
      • Viral exanthems
      • Based on exposure/vaccination hx: Measles, rubella, varicella
    • Mycobacteria
      • Miliary tuberculosis (most common rash is TB cutis miliaris disseminate)
    • Fungal
      • Endemic mycoses
    • Primary dermatologic
      • Lifethreatening drug reaction* – DRESS, AGEP, SJS/TEN
      • Psoriasis or eczema with superinfection (like eczema herpeticum)
    • Inflammatory
      • Dermatomyositis
      • Acute rheumatic fever
      • Kawasaki’s disease
    • Malignant
      • Paraneoplastic NOS
      • dermatomyositis

Cervical lymphadenopathy and lymphadenitis

Big picture wisdom

  • Bacterial lymphadenitis (which this patient was originally thought to have) is rare in adults. In children it is usually caused by staph, strep, or TB (scrofula)
  • Ddx changes based on whether adenopathy is unilateral, bilateral, tender or non-tender

Ddx for tender, unilateral cervical adenopathy


  • Staph/strep lymphadenitis
  • Tuberculous lymphadenitis
  • Viral (HIV/EBV/CMV)
  • Based on exposure – syphilis, toxoplasmosis, bartonella

Malignant (usually nontender, but could theoretically be superinfected)

  • lymphoma
  • metastatic dz esp head and neck cancer
  • lymphoproliferative disorder (including castlemans disease)


  • Kikuchi’s disease (self limited lymphadenitis, usually seen in young women).
  • SLE
  • Kawasaki’s disease
  • sarcoidosis

Med effect






Ely JW1, Seabury Stone M. The generalized rash: part I. Differential diagnosis. Am Fam Physician. 2010 Mar 15;81(6):726-34.

Ferrer R. Lymphadenopathy: differential diagnosis and evaluation. Am Fam Physician. 1998;58(6):1313.

Is it poor form to cite Uptodate? They had the most comprehensive approach to fever and rash that I could find outside of a textbook. Here you go:

Lopez FA, Sanders CV. Fever and rash in the immunocompetent patient. UpToDate. http://www.uptodate.com/contents/fever-and-rash-in-the-immunocompetent-patient?source=search_result&search=fever+rash&selectedTitle=1~150 Accessed 6/13/2016


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s