When polymerase chain reaction does not help: cytomegalovirus pneumonitis associated with very low or undetectable viral load in both blood and bronchoalveolar lavage samples after lung transplantation.

Cytomegalovirus (CMV) pneumonitis occurs frequently among solid organ transplant recipients and is classically associated with significant viral replication in both blood and bronchoalveolar lavage (BAL) samples. We present a case of a 64-year-old lung transplant recipient who presented with CMV pneumonitis that was diagnosed based on the association of viral inclusion in the BAL sample, rapid response to ganciclovir, and absence of other infectious etiology. Surprisingly, we observed very low or undetectable viral load both in blood and BAL samples. Diagnosis of CMV pneumonitis should rely on the association of clinical, pathological, radiological, and microbiological signs, while quantitative nucleic acid amplification testing should be interpreted with caution.