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imaging with CT or MRI oncology and neurosurgery in the setting of spinal cord compression a Consider whether renal function or metabolic derangements may necessitate dialysis BUN, blood urea nitrogen; PT, prothrombin time; PTT, partial thromboplastin time; TLS, tumor lysis syndrome; q, every; IV, intravenous; WBC, white blood cell; CT, computed tomography; ANC, absolute neutrophil count; NSAIDs, nonsteroidal anti-inflammatory drugs; CNS, central nervous system; MRI, magnetic resonance imaging In constructing a differential diagnosis, it is helpful to consider whether leukemic blasts are present in the peripheral circulation If blasts are present in substantive quantities (greater than 20%), then leukemia is the most likely diagnosis A smaller percentage of blasts could indicate a myelodysplastic syndrome, a myeloproliferative disorder, recovery from an aplastic process, or a leukemoid reaction If blasts are not evident on the CBC, and the patient has pancytopenia, one must consider not only leukemia but also bone marrow failure from aplastic anemia, infection (usually viral), or marrow replacement by a solid tumor If only one or two cell lines seem to be affected, the clinician should consider the differential diagnoses for each cytopenia individually (see Chapter 93 Hematologic Emergencies ) In addition to the laboratory investigations needed for diagnosis, screen for metabolic abnormalities due to tumor lysis by checking serum chemistries, including potassium, calcium, magnesium, phosphorus, and uric acid Renal function should be assessed with a blood urea nitrogen (BUN) and creatinine The results of the CBC should be reviewed to assess needs for transfusions of blood products and a prothrombin time (PT) and partial thromboplastin time (PTT) should be checked to look for coagulopathy ( Table 98.3 ) A chest x-ray may indicate the presence of a mediastinal mass, or pericardial or pleural effusion Management Cytopenias As the leukemia proliferates in the bone marrow it disrupts the normal production of cell lines leading to anemia, thrombocytopenia, and neutropenia This is most common in the setting of leukemia but can also occur with solid tumors, such as neuroblastoma and rhabdomyosarcoma with bone marrow metastasis Anemia can be mild or severe but is often asymptomatic because of its slow development Anemia with associated clinical signs or symptoms should be treated with a red cell transfusion Severely anemic but stable patients should be transfused slowly to avoid rapid development of pulmonary edema and respiratory failure Thrombocytopenia can present with mucocutaneous bleeding such as epistaxis, gingival bleeding, petechiae, and ecchymosis The risk of bleeding may also be
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