Chronic Lymphocytic Leukaemia / Small Lymphocytic Lymphoma

Chronic lymphocytic leukaemia (CLL) and small lymphocytic lymphoma (SLL) are the same disease process but differentiated based on clinical and pathological findings.

  • CLL is the most common presentation
  • SLL alone is uncommon (< 10% of diagnoses compared to CLL) and also represents an uncommon cause of lymphoma in adults (< 10%); this diagnosis is only given when the levels of circulating B lymphocytes in the blood is < 5 x 109 per litre.

Basic Sciences

A variety of genetic changes in SLL/CLL have been described but none are particularly prevelant.
On light microscopy, lymph nodes are replaced with a psuedofollicular pattern, with small round blue cells congregating around pale, larger cells centrally. Immunohistochemistry is positive for membrane immunoglobulin (of one type only), but negative for cyclin D1 (excludes mantle cell lymphoma). B cell markers are present.