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• Chronic lymphocytic leukemia must be differentiated from other diseases that cause weight loss, night sweats, hepatosplenomegalyand, and palpable lymph nodes, such as hairy cell leukaemia, prolymphocytic leukaemia, follicular lymphoma, and mantle cell lymphoma.
• The table below summarizes how to differentiate chronic lymphocytic leukemia from other conditions that cause similar presentation:

Differential Diagnosis	Surface Immunoglobulin	CD5	CD22/FMC7	CD23	CD79b	CD103
Chronic lymphocytic leukaemia	Weakly positive	Positive	Negative	Positive	Negative	Positive/Negative
Prolymphocytic leukaemia	Strongly positive	Negative	Positive	Negative	Positive	Negative
Hairy cell leukaemia	Strongly positive	Negative	Positive	Negative	Positive/Negative	Positive
Mantle cell lymphoma	Positive	Positive	Strongly positive	Negative	Strongly positive	Negative
Follicular lymphoma	Strongly positive	Negative	Positive	Negative	Strongly positive	Negative