A Narrative Review of Lung Cancer Cytology in the Times of Coronavirus

What Physicians Should Know

Pasquale Pisapia; Umberto Malapelle; Maria Salatiello; Rafael Rosell; Giancarlo Troncone


Transl Lung Cancer Res. 2020;9(5):2074-2081. 

In This Article

BAL and SARS-CoV-2

Nasopharyngeal and oropharyngeal (NP/OP) swabs are commonly used to detect the SARS-CoV-2 RNA; these upper respiratory tract specimens, however, may yield false negative results, reflecting suboptimal NP/OP tissue sampling.[31] Moreover, nasal and pharyngeal cells do not express receptors able to bind SARS-CoV-2; conversely these receptors are abundant on the cell membranes of type I and type II alveolar epithelial cells, explaining a persistent virus detection in lower respiratory tract specimens.[32] Thus, according to World Health Organization (WHO) guidelines,[33] negative specimens from the upper respiratory tract do not exclude the diagnosis, and additional lower respiratory tract samples are recommended in cases with clinical and radiological suspicion of coronavirus disease 19 (COVID-19) pneumonia.[34] Beyond the clinical management of the patients, BAL yields microenvironment relevant information on bronchioles and lung alveoli.[35] In particular, a recent study performed single-cell RNA sequencing on BAL cells showing that proinflammatory monocyte-derived macrophages are abundant in the BAL fluid from patients with severe COVID-19 pneumonia, whereas presence of highly clonally expanded CD8+ T cells is associated to a less aggressive disease course.[35] From a microscopy point of view, together with generic morphologic features of viral infection such as cytomegaly, syncytia formation, intracytoplasmic and intranuclear inclusions, in the COVID-19 BAL specimen, case reports described exuberant plasmacytosis with a large number of activated CD138 positive cells[36] or hemosiderin-laden macrophages identified by specific staining, such as Perls stain or immunocytochemical technique to detect ferric iron.[37]