Key Clinical Questions
How do the most common hematologic malignancies present?
How do you definitively diagnose these malignancies?
How do you stage these diseases?
How do you determine prognosis for patients with each of these malignancies?
Which are the standard treatment options for these malignancies and what are their side effects?
Hematologic malignancies represent a growing percentage of inpatient oncology admissions. Patients with these diseases may receive a significant portion of their cancer-specific treatment in the hospital under the supervision of hematology specialists. Admitting clinicians should be able to recognize common presentations, arrange for prompt hematology or oncology consultation, explain standard treatment protocols, and anticipate complications that may arise during their course.
The cellular origin of the various hematologic malignancies will dictate the downstream disease manifestations and treatment options. The cancer ultimately derives from a single cancer cell which has undergone a sufficient string of genetic mutations to allow for unchecked and exponential replication (a “clonal” process). Some pathologies may be “polyclonal,” coming from multiple over replicating cells. This chapter will focus on “monoclonal” entities that may be traced back to mutations in a single cell which has copied itself prolifically.
Myeloid neoplasms, such as acute myeloid leukemia, myelodysplastic syndrome, and the myeloproliferative neoplasms, tend to arise from an aberrant primitive hematopoietic cell. In contrast, lymphoid neoplasms may arise from malignant transformation at various points along the maturation process of B or T lymphocytes. This may manifest as an acute lymphoblastic leukemia, chronic lymphocytic leukemia/small lymphocytic lymphoma, or one of the many other types of B- or T-cell lymphomas.
“Leukemia” generally refers to cancers more predominantly localized in the marrow and peripheral blood, whereas “lymphoma” refers to disease burden within the lymph nodes and lymphatic system. However, many hematologic malignancies may situate in either or both categories during their course.
TECHNIQUES USED IN THE EVALUATION OF HEMATOLOGIC MALIGNANCIES
BONE MARROW BIOPSY AND ASPIRATE
The most common study to evaluate hematologic malignancies is the bone marrow biopsy and aspirate. This two-step procedure includes bone marrow biopsy for examination of cellularity and morphology and bone marrow fluid aspiration for cytogentics and molecular studies. A core piece of bone marrow generally 0.2 cm in width and 1 to 1.5 cm in length is obtained using a Jamshidi needle, after which immunohistochemical staining may be performed to optimize elucidation of malignant cells. An additional 5 to 10 mL of marrow fluid is collected into an EDTA tube for smears and flow cytometry, and into a sodium heparin tube for cytogenetic analysis.
Flow cytometry is critical in the diagnosis of leukemias. This laser-based analytical technique is used to evaluate the surface markers on individual cells. Cells from the given tissue sample are incubated with fluorescent-labeled tags and then run as a ...