Investigations
1st investigations to order
FBC count with differential
Test
Required for diagnosis and staging.
Patients with CLL usually present with absolute lymphocytosis as an incidental finding on a routine FBC.
A diagnosis of CLL requires an absolute monoclonal B-lymphocyte count ≥5 × 10⁹/L (≥5000 cells/microlitre) in the peripheral blood that persists for at least 3 months, and clonality of B lymphocytes confirmed by flow cytometry.[2][33]
Patients may present with cytopenias (anaemia, thrombocytopenia), which could be disease-related (i.e., due to leukaemic cells infiltrating the bone marrow) or related to an autoimmune complication (e.g., autoimmune haemolytic anaemia, immune thrombocytopenic purpura).[2][34][35]
The presence of cytopenias can guide staging and treatment. See Diagnostic criteria and Management sections..
Result
elevated WBC count with absolute lymphocytosis (monoclonal B lymphocyte count ≥5 × 10⁹/L (≥5000 cells/microlitre); anaemia (Hb <110 g/L [<11 g/dL]) and/or thrombocytopenia (platelets <100 × 10⁹/L [<100,000/microlitre]) may be present
flow cytometry
Test
Required for diagnosis.
Flow cytometry confirms the immunophenotype and clonality of circulating B lymphocytes.[2][33]
Flow cytometry may also identify markers for prognostication (e.g., zeta-associated protein [ZAP-70], CD38, and CD49d).[2][28][29][30] Although expression of ZAP-70, CD38, or CD49d predict a worse prognosis, there is no evidence to suggest that early treatment improves survival in patients with these markers.
Result
typical immunophenotype of CLL: CD5+, CD23+, CD43+/-, CD10-, CD19+, CD200+, CD20 dim, surface immunoglobulin (sIg) dim+ (with restricted expression of either kappa or lambda immunoglobulin light chains), and cyclin D1-; prognostic markers (e.g., ZAP-70, CD38, CD49d) may be present
peripheral blood smear
Test
Required to identify (morphologically) the presence of CLL cells in the blood.[2][36][37] Leukaemic cells appear as small, mature lymphocytes with a narrow border of cytoplasm and a dense nucleus lacking discernable nucleoli and partially aggregated chromatin.
Smudge cells (damaged lymphocytes) are a common finding on a blood smear of patients with CLL.[38] Patients with higher numbers of smudge cells typically experience less aggressive disease.[38][39] Smudge cells are not diagnostic of CLL.
Result
presence of leukaemic cells; smudge cells may be present; spherocytes and polychromasia may be present if there is active haemolysis
Investigations to consider
serum beta-2 microglobulin
Test
An important prognostic factor that is included in the CLL International Prognostic Index (CLL-IPI; see Diagnostic criteria section).[33][40]
Elevated serum beta-2 microglobulin is associated with a poor prognosis.[41][42]
Result
may be elevated
fluorescent in situ hybridisation (FISH)
Test
Peripheral blood should be subject to FISH (cytogenetic analysis) to help determine prognosis and to aid treatment decisions.[2][33][36]
Cytogenetic abnormalities identified in CLL that have prognostic significance include: del(13q), del(11q), trisomy 12, and del(17p).[25] Del(17p) is associated with resistance to chemoimmunotherapy, rapid disease progression, and a poor prognosis. [25][43]
Result
may show cytogenetic abnormalities (e.g., del(13q), del(11q), trisomy 12, del(17p))
molecular genetic tests
Test
Used to determine TP53 and immunoglobulin heavy chain (IgHV) mutation status, which can inform prognosis and treatment.[2][33]
TP53 gene mutations are associated with a poor prognosis.[23] Patients with mutated IgHV have a good prognosis and respond well to chemotherapy.[46][47][48]
Other genetic mutations of potential clinical relevance include NOTCH1, SF3B1, ATM, and BIRC3; however, their role in guiding management of CLL requires further investigation.[22][36][44]
Result
may show genetic mutations (e.g., IgHV, TP53)
direct antiglobulin test (DAT)
Test
Ordered if patient is anaemic.
Result
positive test suggests autoimmune haemolytic anaemia
serum quantitative immunoglobulin
Test
Ordered if patient has recurrent infections.
Result
may show hypogammaglobulinaemia
lymph node biopsy
Test
Can be used for diagnosis if flow cytometry of peripheral blood is not diagnostic.[33]
If a lymph node is not easily accessible for excisional or incisional biopsy, a combination of core needle biopsy and fine-needle aspiration (FNA) biopsy (with appropriate immunophenotyping, e.g., flow cytometry) may be sufficient for diagnosis.[33]
Core needle or FNA biopsy alone is not suitable for diagnosing CLL.
Result
typical immunophenotype of CLL: CD5+, CD23+, CD43+/-, CD10-, CD19+, CD200+, CD20 dim, surface immunoglobulin (sIg) dim+ (with restricted expression of either kappa or lambda immunoglobulin light chains), and cyclin D1-
bone marrow aspirate and trephine biopsy
Test
Can be used for diagnosis if peripheral blood tests and lymph node biopsy are not diagnostic.[33]
Can help to determine whether cytopenias (anaemia, thrombocytopenia) are disease-related (i.e., due to bone marrow infiltration) or autoimmune-relatedd (e.g., autoimmune haemolytic anaemia, immune thrombocytopenic purpura), prior to initiating myelosuppressive therapies.[2][33][36]
Result
may show marrow infiltration by leukaemic cells, reduction in haematopoetic precursor compartment
CT scan/fluorodeoxyglucose (FDG)-PET/CT
Test
Imaging studies (i.e., CT) are not generally required for diagnosis, staging, or follow-up.[2][33][36][37][45]
CT scans do not improve the outcome for patients with early-stage CLL and do not aid with staging or prognosis; they also expose patients to radiation and may detect incidental, clinically irrelevant findings that lead to further tests.[45]
Staging is based on physical examination and blood counts (see Diagnostic criteria section).[2][37]
CT scan may be used to assess symptoms of bulky disease, or to assess the risk for tumour lysis syndrome (TLS) prior to initiating treatment (e.g., venetoclax).[33][36]
Fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT scan may be used to direct nodal biopsy if histological (Richter) transformation is suspected.[33]
Result
may show hepatosplenomegaly; retroperitoneal or mediastinal adenopathy
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