Small Lymphocytic Lymphoma / Chronic Lymphocytic Leukemia
Definition
- Neoplasm composed primarily of small round B lymphocytes that can range from solid (small lymphocytic lymphoma) to leukemic (chronic lymphocytic leukemia)
Alternate/Historical Names
- Mu heavy chain disease (variant)
- Well differentiated lymphocytic lymphoma
Diagnostic Criteria
- Small lymphocytic lymphoma (SLL) and chronic lymphocytic leukemia (CLL) are histologically indistinguishable
- CLL defined as having circulating B lymphocytes > 4000/mm3
- Architecture effaced by sheets of small B lymphocytes
- Predominant population similar to cells of primary follicles
- Clumped chromatin, small or inconspicuous nucleoli
- Plasmacytoid differentiation may be prominent
- Vacuolated plasma cells present on bone marrow biopsy in Mu heavy chain variant
- Frequent extracapsular extension
- Occasional more limited patterns: perifollicular, interfollicular or marginal zone
- May involve extranodal sites, especially if leukemic
- Pseudofollicular proliferation centers frequent
- Pale, vague nodules containing larger prolymphocytes and paraimmunoblasts
- Mitotic figures may be frequent in proliferation centers
- Prolymphocytes
- Slightly larger nucleus than typical small lymphocytes
- Less condensed chromatin
- Small but distnct nucleoli
- Slightly more cytoplasm
- Slightly larger nucleus than typical small lymphocytes
- Paraimmunoblasts
- Intermediate to large cells
- Partially vesicular nucleus, prominent central nucleolus
- Delicate nuclear membrane
- Transformation to diffuse large B cell lymphoma (Richter syndrome) in 10-20% of cases
- May show immunoblastic features
- Generally retains same phenotype
- Genetic study may show different clone in up to 40% of cases
- Clinically abrupt worsening of symptoms or tumor growth
- Transformation to Hodgkin lymphoma rare (0.5-2%)
- May be all types of classical Hodgkin lymphoma
- Usual Hodgkin phenotype
- Most cases EBV RNA positive by in situ hybridization
- Rare cases of nodular lymphocyte predominant Hodgkin lymphoma reported
- Both cases CD20 negative, one with discordant light chain
- Most but not all show same clone
- May be all types of classical Hodgkin lymphoma
- Prolymphocytic transformation
- CLL with increased prolymphocytes
- 11-55% circulating prolymphocytes
- May be refractory to treatment and have worse prognosis
- CLL with prolymphocytic transformation
- Over 55% circulating prolymphocytes
- May be refractory to treatment and have worse prognosis
- CLL with increased prolymphocytes
- Peripheral T cell lymphoma has been described associated with SLL/CLL
- Paraimmunoblastic variant
- Diffuse population of paraimmunoblasts with interspersed prolymphocytes and small lymphocytes
- Mitotic rate 15-50%
- May have starry sky macrophages
- Half of cases leukemic but circulating prolymphocytes always <10%
- Same clinical behavior as usual SLL/CLL
- Reported incidence 2% of SLL/CLL
- Separation from other small B cell lymphomas requires immunologic study
Yasodha Natkunam MD PhD
Dita Gratzinger MD PhD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting:: May 1, 2006
