Uncovering the Cause of Pneumonia: Reactivation of HHV-6B in an Immunocompromised Patient.

Human herpesvirus 6 (HHV-6) is a ubiquitous virus that commonly infects the paediatric population and establishes latency in the host following primary infection. As in other herpesviruses, HHV-6 may reactivate when the immune system becomes severely compromised, such as after chemotherapy or haematopoietic cell transplantation. We report a case of an 83-year-old male, previously diagnosed with multiple myeloma and treated with lenalidomide plus bortezomib, who was admitted to the internal medicine department with bilateral pulmonary thromboembolism. During his stay, he developed severe respiratory dysfunction and fever. A diagnosis of nosocomial pneumonia was established based on imaging and blood tests. Despite broad-spectrum antibiotic therapy the patient remained febrile with worsening respiratory function and developed an erythematous rash on the face and trunk. The chest CT scan revealed scattered ground-glass opacities bilaterally. Investigations for opportunistic agents (serologies and DNA) were also performed, with positive IgM cytomegalovirus (CMV) antibodies, but negative CMV antigen and DNA quantification, while serum DNA was positive for HHV-6. Antibiotics were discontinued and bronchoalveolar lavage (BAL) was performed with HHV-6 polymerase chain reaction (PCR) testing positive, identifying HHV-6B. Treatment with intravenous ganciclovir led to the resolution of symptoms and hypoxaemia. The patient was discharged and completed 21 days of valganciclovir at home. After one year, the patient remains on chemotherapy without pulmonary sequelae or new HHV-6B reinfection. LEARNING POINTS: Human herpesvirus 6 (HHV-6) can reactivate in immunocompromised individuals and cause severe atypical pneumonia, so it is important to recognise this entity when a patient fails to improve their clinical outcome with conventional therapy.In patients diagnosed with pneumonitis, DNA PCR testing can detect HHV-6 from bronchoalveolar lavage fluid making this a powerful diagnostic tool.Treatment options for HHV-6 pneumonitis should be considered, such as combined ganciclovir and foscarnet or, as in our case, oral valganciclovir can be a good alternative.