<prompt> Which of the following is a stain for hea failure cells?PASPrussian blueSudan blackOil red  <response>: Prussian blue is the stain for hea failure cells. The red cells in the congested alveoli undergo hemolysis and release the heme which is conveed to hemosiderin. This is seen as brown granules in HE stained sections and blue in Pearls stain Prussian blue reaction. The hemosiderin granules are present free in the alveolar wall and inside the alveolar macrophages within the alveolar lumens. These clusters of hemosiderin laden phagocytic cells are known as the hea failure cells. Ref: Textbook of Pathology By Datta, 2004, Page 121 