A greenish tumor or mass of immature blood cells (myeloblasts) that occurs in leukemia patients, so named for its characteristic green color.
From chloro- 'green' (from chlorophyll's greenness) + -oma 'tumor'. The term emerged in 1850s medical literature when pathologists described this peculiar finding in leukemia patients.
Chloromas appear green because the leukemia cells contain an enzyme called myeloperoxidase, which reacts with hemoglobin to produce a greenish pigment—it's like the cancer cells are literally advertising their abnormality through color.
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