Histopathological identification of hepatic intramitochondrial crystalloid inclusions (IMCI)

A 45-year-old female with systemic lupus erythematosus underwent liver biopsies twice during the period of cefazolin administration and a complication of cefazolin-induced toxic hepatitis was strongly suggested. Histologically, a small number of spindle-shaped, esoinophilic crystalloid bodies were faintly noticed in the cytoplasm of hepatocytes in hematoxylin and eosin-stained sections, while they showed strong positivity for strains inherent to mitochondria as well as specific to phospholipid and sharply showed a spindle or needle shaped configuration. Moreover, they greatly increased in number in these sections. They were distributed throughout the the parenchyma but were prominent in the degenerated hepatocytes with slight fatty metamorphosis. Electron microscopically, they proved to correspond to the intramitochondrial crystalloid inclusions (IMCI). Despite many ultrastructural descriptions of the IMCI, precise histopathological examination of the IMCI referring to the staining property on the deparaffinated sections has not yet been described since the first report of the IMCI by Napolitano (1958).