Chronic lymphocytic leukemia differential diagnosis

Differential diagnosis
Hematologic disorders that may resemble CLL in their clinical presentation, behavior, and microscopic appearance include mantle cell lymphoma, marginal zone lymphoma, B cell prolymphocytic leukemia, and lymphoplasmacytic lymphoma.
 * B cell prolymphocytic leukemia (B PLL), which is a related but more aggressive disorder, has cells with similar phenotype but that are signficantly larger than normal lymphocytes and have a prominent nucleolus suggests a related.
 * Hairy cell leukemia is also a neoplasm of B lymphocytes but differs significantly from CLL by its morphology under the microscope (hairy cell leukemia cells have delicate, hair-like projections on their surface) and marker molecule expression.

All the B cell malignancies of the blood and bone marrow can be differentiated from one another by the combination of cellular microscopic morphology, marker molecule expression, and specific tumor-associated gene defects. This is best accomplished by evaluation of the patient's blood, bone marrow and occasionally lymph node cells by a pathologist with specific training in blood disorders. A sophisticated instrument called a flow cytometer is necessary for cell marker analysis and the detection of genetic problems in the cells may require visualizing the DNA changes with fluorescent probes by fluorescent in situ hybridization (FISH). CLL is positive for CD5, CD19 & CD23; CLL is the only cell type that coexpresses CD5 & 19. It is negative for CD10 & cyclin D. CD20 is +/- as is sIg. 90% of B-CLL have bcl-2. The 2 most noteworthy lymphoproliferative diseases with CD5 positivity are CLL (which is CD23 positive) & mantle zone lymphoma (which is CD23 negative). Other CD5+ groups include peripheral & cutaneous T-cell lymphoma, lymphoblastic lymphoma, and Adult T-cell leukemia/lymphoma.