The New England Journal of Medicine (NEJM) publishes interesting presentations of common diseases and unusual cases in the Clinical pathology Conference (CPC) series. These cases are educational and can pose diagnostic challenges even to the expert physicians at the Massachusetts General Hospital.
Using the clinical features of these cases you can evaluate your own diagnostic skills and compare your diagnostic performance to that of the physicians at MGH. If you are registered with Isabel as a client or have a free-trial subscription, you can use the diagnosis reminder system and run through some scenarios to get a list of likely suspects. Clicking on a diagnosis will take you through to various knowledge sources and links available from within Isabel.
Demographic: Male, 60 yrs, North America
STOP! Before you read further, create your own differential diagnosis.
Differential Diagnoses considered by the MGH panel: Meningococcemia
Final Diagnosis of the case according to NEJM and Isabel: Rocky mountain spotted fever
Was the final diagnosis given by the Isabel system: Yes, Rocky mountain spotted fever in the category of Infectious. See the Isabel system screenshot below, showing the data entered on the left about the patient, and the differential diagnosis list that appeared on the right after the system completed its query.
Rocky Mountain spotted fever is lethal and a frequently reported rickettsial illness in the United States. It has been diagnosed throughout the Americas. Some synonyms for Rocky Mountain spotted fever in other countries include “tick typhus,” “Tobia fever” (Colombia), “São Paulo fever” or “febre maculosa” (Brazil), and “fiebre manchada” (Mexico). It is distinct from the viral tick-borne infection, Colorado tick fever. The disease is caused by Rickettsia rickettsii, a species of bacterium that is spread to humans by Dermacentor ticks. Initial signs and symptoms of the disease include sudden onset of fever, headache, and muscle pain, followed by development of rash. The disease can be difficult to diagnose in the early stages, and without prompt and appropriate treatment it can be fatal. More about Rocky Mountain Spotted fever from Wikipedia.