LEUKEMIA

Blood cancer


Leukemia is a cancer of the bone marrow. You should suspect Leukemia when a patient presents with lymphadenopathy, vague symptoms (fatigue, malaise) and they have a wonky CBC. For example, a WBC is 50K (normal is 4K to 10K). As you look further into the CBC differential, expect to see more weirdness, such as one cell line being super dominant. Other times, the WBC will be very low. The gold standard diagnostic test for leukemia is to do a bone marrow biopsy. Now count the blasts. If over 20% of the marrow’s cells are blasts, then it’s "acute." And if it’s less than 20%, then it’s "chronic."

How does leukemia cause symptoms? By overcrowding the bone marrow. When too many cancerous cells occupy the marrow, there is no room left for the normal healthy blood cells. Patients get fatigued and tachycardic (from anemia). They have recurrent infections (from the leukopenia). They get bleeding or clotting (from the thrombocytopenia). They can even have bone pain (from the expanding pressure inside the bone marrow). The healthy blood cells are pushed into the spleen, lymph nodes and liver, causing hepatosplenomegaly and lymphadenopathy. 

Acute leukemias are neoplasms of immature stem cells in the blood, aka "blast" cells. The word "acute" is used because the symptoms are severe and have a swift onset. Acute leukemia can kill in a matter of weeks. 

Chronic leukemias are neoplasms of mature cell lines, for example T-cells. Chronic leukemias are often slow growing and insidious.