Which of the following is the most serious complication of varicella that might occur in this patient?

A 6-year-old girl with acute lymphocytic leukemia (ALL) is admitted to the hospital with a generalized vesicular rash and high fever. She has no previous history of chickenpox and has never received immunization for varicella. Her 4-year-old sister recently recovered from chickenpox that started about 10 days ago. On admission, her temperature is 38.4 C (101.1 F), blood pressure is 94/58 mm Hg, pulse is 80/min, and respirations are 20/min. Which of the following is the most serious complication of varicella that might occur in this patient?

A. Arthritis
B. Cellulitis
C. Endocarditis
D. Hepatitis
E. Pneumonia

Explanation: The correct answer is E. Varicella (chickenpox) usually presents with cutaneous infection in immunocompetent hosts. However, in immunocompromised patients, such as this girl with acute lymphocytic leukemia (ALL), varicella can cause serious and life-threatening complications, such as varicella pneumonia. Varicella pneumonia has a very poor prognosis in patients with ALL, reaching a mortality of roughly 25%. The clinical course usually deteriorates rapidly and many patients die within 3 days of the diagnosis. Pneumonia is exceedingly rare in normal children, but it can happen in older adults.

IV acyclovir therapy is indicated in immunocompromised patients with varicella infection. Therapy should be initiated early in the disease course to maximize efficacy of the treatment. Varicella-zoster immune globulin (VZIG) may modify the disease course if it is given shortly after the exposure. It is not useful, however, once the disease is established, as in this clinical vignette. Children with varicella also should not be given salicylates because of a theoretically increased risk of subsequent Reye syndrome. Patients should be both contact- and airborneisolated during the entire course of the illness.

Other, less common, complications include encephalitis, hepatitis, glomerulonephritis, arthritis, and thrombocytopenia.