Heart, Myocardium - Vacuolation, Cytoplasmic
comment:Cardiomyocyte vacuolation ( Figure 1 , Figure 2 , Figure 3 , and Figure 4 ) is considered to be a degenerative process, consisting of multifocal or widespread accumulation of multiple, welldemarcated, round, variably sized (primarily small), clear vacuoles. Vacuoles are found within the cardiomyocyte sarcoplasm and occasionally coalesce into larger vacuoles. Myofiber cytoplasmic vacuolation can be the only morphologic manifestation seen in cardiotoxicity or may be associated with other changes reflecting cardiotoxicity (e.g., myofiber necrosis, mononuclear cell infiltration, fibrosis), or it may be a minor component in the case of spontaneous cardiomyopathy. Ultrastructural analysis of heart tissue from chemical-related myofiber vacuolation has elucidated the primary site of damage in various organelles, including mitochondria and smooth endoplasmic reticulum. Vacuole formation occurs in damaged mitochondria with loss of cristae, subsequent swelling and possible coalescence
due to disintegration of their outer membranes. In other cases, vacuolation forms from distension of the sarcoplasmic reticulum within cardiomyocytes. Electron microscopic examination may be used to positively identify the source and content of the vacuoles.
recommendation:Cytoplasmic vacuolation of the cardiomyocytes should be diagnosed whenever present. It should be graded based on the extent of the lesion. The distribution of the vacuolation (i.e., focal, multifocal, or diffuse), as well as the location (i.e., right, left, or interventricular wall), should be described in the pathology narrative. If vacuolation is considered part of the spectrum of changes in cardiomyopathy, it should not be diagnosed separately but may be mentioned in the pathology narrative.
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