Identifying <scp>HHV</scp>‐6 Induced Cytopathic Effects in Bronchoalveolar Lavage Fluid Preparations to Enhance Care in Immunocompromised Patients

Human Herpesvirus 6 (HHV-6) is a ubiquitous virus that remains latent after primary infection but can reactivate in immunocompromised patients, leading to severe complications. Early detection of HHV-6 in respiratory samples is critical for timely intervention. We describe a 61-year-old immunocompromised woman who presented with pneumonitis and encephalopathy. Initial testing confirmed COVID-19, and worsening respiratory symptoms prompted bronchoalveolar lavage (BAL). Cytologic analysis of the BAL revealed epithelial cells with viral cytopathic effects, including multinucleation, chromatin margination, and nuclear inclusions. Plasma polymerase chain reaction (PCR) detected a high HHV-6 viral load, confirming HHV-6 pneumonitis and encephalitis. Despite antiviral treatment with Foscarnet and Ganciclovir, the patient's condition deteriorated, ultimately leading to her passing. This case highlights the importance of recognizing differential diagnoses of cytopathic effects in BAL specimens. Pathologists are crucial in identifying viral, infectious, or inflammatory conditions in BAL fluid, aiding in prompt diagnosis and management to improve patient care and prevent severe outcomes.