Giant mitochondria in acute lymphocytic leukemia.

Giant mitochondria were observed in 2 cases among 28 cases of ALL by electron microscopy. The cristae of the giant mitochondria in the leukemic cells were irregularly arranged, decreased in number, and formed concentric circles. Several morphological abnormalities were also observed in the normal mitochondria. Morphometric analysis of the mitochondria in the 2 patients disclosed that the sizes of mitochondria were well distributed from small to large and thus, the mitochondria could not be divided into different populations. Also, there were no clear differences in the distribution of shape between normal and giant mitochondria. These results suggest that the giant mitochondria were derived from normal mitochondria. Since they were observed before the initial treatment, they did not developed as a result of drug action.