The study of the leprous foamy cell by Álvarez Cascos and Llombart

Virchow’s foamy cell, a key element in the diagnosis of leprosy, underwent various morphological reinterpretations throughout the 19th century. Since its initial description by Virchow, numerous hypotheses have been proposed concerning the origin of its foamy appearance, its potential to harbour leprosy bacilli, and its ability to actively internalise bacilli through phagocytic activity. In this article, we focus on the application of silver impregnation techniques developed by the Pío del Río-Hortega school, as employed by Álvarez-Cascos and Llombart in their study of Virchow cells, ultimately leading to their identification as macrophages actively engaged in bacterial phagocytosis.