A 6-year-old boy is brought to the emergency department by his parents due to a sudden onset of high fever, vomiting, lethargy, and purpuric rash over the past 12 hours. He has no significant past medical history and does not take any medications. Vital signs show a temperature of 39.5°C (103.1°F), blood pressure of 70/40 mmHg, heart rate of 150/min, and respirations of 30/min. On physical examination, the patient appears critically ill. There are multiple petechiae and purpuric lesions noted on his extremities and trunk. Laboratory tests reveal the following:
Given the clinical presentation and laboratory findings, which of the following is the most likely diagnosis?
D) Meningococcemia with Waterhouse-Friderichsen syndrome
The patient's presentation of high fever, vomiting, lethargy, purpuric rash, and hypotension suggests a severe systemic infection. The combination of shock, purpura, and laboratory findings (e.g., low sodium, high potassium, and hypoglycemia) points to adrenal insufficiency. Waterhouse-Friderichsen syndrome is most commonly caused by sepsis due to Neisseria meningitidis, leading to adrenal hemorrhage and acute adrenal insufficiency.
Answer choice A: Acute lymphoblastic leukemia, is incorrect. ALL typically presents within this age group (0-15 years age) with fatigue, pallor, petechiae, and infections but does not typically cause acute adrenal insufficiency and shock with a purpuric rash.
Answer choice B: Disseminated intravascular coagulation, is incorrect. DIC can present with purpura and bleeding from multiple sites but does not present with the constellation of findings described in this vignette.
Answer choice C: Hemolytic uremic syndrome, is incorrect. HUS typically presents with the triad of hemolytic anemia, thrombocytopenia, and acute kidney injury, often following a diarrheal illness specifically E. coli (Escherichia coli O157:H7).
Answer choice E: Rocky Mountain spotted fever, is incorrect. Rocky Mountain spotted fever can cause fever and rash, but the rash usually starts on the wrists and ankles and spreads centrally with a history of out-door activity such as summer camp.
Key Learning Point
Waterhouse-Friderichsen syndrome results from hemorrhage into the adrenal glands with resulting adrenal insufficiency, usually as a result of a severe bacterial infection, most commonly meningococcal septicemia. In addition to hypotension, look for the laboratory indicators of adrenal insufficiency, including low sodium, high potassium, and hypoglycemia.
