Adenoviral cytopathic changes in pleural fluid: A unique cytological presentation mimicking malignancy

Adenoviruses are emerging as important viral pathogens in immunocompromised patients due to immunodeficiency diseases and recently hematopoietic stem cell and solid organ transplant recipients, impacting morbidity and even mortality. Immunocompromised children are prone to respiratory infection, due to alterations in their immune system. When confronted with diseases involving the pleural effusions, such as viral infections, the diagnostic problem becomes more complex and special effort is needed to recognize and characterize them accurately and to differentiate them from other pathologies such as malignancies. However, cytology of adenoviral infection in pleural effusions has not been reported before. We report a case of an adenovirus infection of the pleural effusion which included lymphocytosis associated with background atypical cells showing a cytopathic effect (cytoplasmic viral particles). The differential diagnosis included lymphoma and infections. Immunohistochemical stain for adenovirus was positive and confirmed by molecular studies. Usually in viral infections there are cytopathic changes due to viral particles affecting epithelial cells but this case is unique as the viral particles were identified in macrophages. We discuss the significance of such infection in comparison with other viral changes indigenous to the pleural effusions, which could also occur in such specimens.