B- cell lymphoproliferative disorders Flashcards
List the differential diagnosis for CD5+ LPDs and how to differentiate between them
1) CLL.
- Most common CD5+ LPD
- Classic morphology: small, mature, monomorphic lymphocytes with clumped nuclear chromatin, round nucleus, high N:C ratio and mildly basophilic cytoplasm.
- Focal nodular or interstitial pattern of infiltration on trephine. Diffuse infiltration and expanded proliferation centres in high risk disease.
- Classic immunophenotype: CD5+ CD19+ B cells. Weak CD20, CD22 and SIg. CD79a weak or absent. CD23 and CD200+
- FMC-, LEF1+
2) MCL.
- Second most common CD5+ LPD
- Classic morphology: small, mature, monomorphic lymphocytes with condensed nuclear chromatin a high N:C ratio and mildly basophilic cytoplasm. Nuclear clefts commonly seen. Many variants (small cell, marginal, pleomorphic, blastic)
- Nodular, paratrabecular, interstitial or diffuse infiltration on trephine.
- Classic immunophenotype: CD5+, CD19+ B cells that are CD20, CD22, CD79a and SIg positive. CD23 and CD200 negative .
- CCND1 and SOX11 positive in classic cases.
- t(11;14) translocation identified on FISH.
3) B-PLL
- CD5 positivity seen in 20-30%
- Monomorphic population of prolymphocytes present (intermediate sized cells, moderately diffuse nuclear chromatin with prominent nucleolus, medium to high N:C ratio with mildly basophilic cytoplasm)
- >55% of lymphocytes must be prolymphocytes.
- Immunophenotype: CD19+, CD20+, CD22+, CD79a+, CD23 in 10-20%. CD200 usually negative. Strong SIg.
- Complex karyotypes, del(17)p/ TP53 mutations common.
4) Marginal zone
- CD5 positivity seen in up to 20% of cases of MZL
- Monomorphic population of intermediate sized lymphoid cells with mature nuclear chromatin and a high N:C ratio. Bipolar cytoplasmic fimbriae in SMZL.
- Nodular or diffuse infiltration on trephine. Can form a germinal centre. Intrasinusoidal in SMZL.
- Immunophenotype not specific: positive for CD19, CD20, CD22, CD79a and SIg. CD10- and usually negative for CD23 and CD200.
- No specific diagnostic features. Often a diagnosis of exclusion. del(7q) seen in a subset and is rare in other LPDs.
5) LPL
- CD5 positivity seen in up to 20% of cases of LPL
- Plasmacytic differentiation present: plasmacytoid lymphocytes present as well as plasma cells (with normal, mature morphology). Increased mast cells (with normal morphology) on aspirate sample.
- Interstitial or diffuse infiltration on trephine. Plasma cells admixed.
- Immunophenotype not specific: positive for CD19, CD20, CD22, CD79a and SIg. CD10- and usually negative for CD23 and CD200.
6) CD5+ DLBCL
- CD5 positivity in 5-10% of DLBCL, usually ABC phenotype.
- Large immature lymphoid cells. Can be pleomorphic.
- High forward scatter on flow cytometry. CD19+, CD20+, CD22+, CD79a+. CD10+/-. High Ki67.
- MYC, BCL2, BCL6 overexpression, translocation variable.
List the immunophenotypic/ genetic features of hairy cell leukaemia
- Flow cytometry: high side scatter. Bright sIg, CD20, CD22 and CD11c. CD25, CD103, CD123 and CD200 positive. FMC7 positive. Usually CD10 negative
- Annexin 1 positive (most specific marker)
- B-RAF V600E
- TBET.
Discuss monoclonal B lymphocytosis
- Refers to a clonal lymphocyte count <5x10^9 in the peripheral blood without any clinical symptoms or signs (cytopenia, lymphadenopathy, hepatosplenomegaly) of an underlying LPD.
- Divided into those with a CLL phenotype vs those with a non-CLL phenotype (associated with a worse prognosis, must exclude an underlying LPD)
- Divided into low count (<0.5x10^9) and high count (>0.5x10^9) MBL
- In those with a CLL MBL, low count is associated with a good prognosis with a very low rate of clinical progression.
- High count CLL MBL is identical to CLL Rai stage 0/ Binet stage A and has a rate of progression to CLL that is 1-2% per year.
- Some MBLs may be transient/ self-limited
What are some of the features of unmutated CLL
- Unmutated CLL is thought derive from an antigen naïve B cell that has not experienced the germinal centre
- Associated with more aggressive disease, chemotherapy resistance and reduced overall survival.
- Advanced stage (C, III, IV)
- Lymphocyte doubling time <12 months
- High ZAP70
- High CD38
- High B2MG
- High-risk cytogenetics (del(17p), complex karyotype)
- Higher rates of clonally related Richter’s transformation
List the poor prognostic features of CLL
1) Clinical
- Age
- Male sex
- CIRS score >6
- Clinical stages (lymphadenopathy, splenomegaly)
2) Lab/ Morphology
- Thrombocytopenia (<100)
- Anaemia (<100- 110)
- Lymphocyte doubling time <12 months
- Increased LDH, B2M
- Atypical morphology
- Diffuse pattern of BM infiltration
- Expanded proliferation centre
- Clonally related Richter’s transformation
3) Immunophenotype
- ZAP70 positive
- CD38 positive
- CD49d positive
3) Molecular
- Del(17p)/ TP53 mutations, complex karyotype
- Unmutated IGHV
- NOTCH1, MYC mutations
What is Richter’s transformation. What different types are there?
- Transformation of CLL to an aggressive diffuse large B cell lymphoma or Hodgkin’s lymphoma
1) DLBCL= most common (2-8% of CLL patients)
- Clonally related= most common= worse prognosis
- Most common in those with unmutated IGHV.
- Associated with mutations in TP53, MYC, CDKN2A and NOTCH1
- Clonally unrelated= least common= same prognosis as de novo DLBCL
- Most common in those with mutated IGHV.
2) Hodgkin’s Lymphoma
- 50% clonally unrelated
- Thought to arise out of immunosuppression due to CLL and therapy
- More common in those with mutated IGHV.
- Poorer prognosis than de novo Hodgkins lymphoma
List the mutations most commonly seen in CLL and the associated prognosis
1) Del(13q)
- 25-40%
- Good prognosis. Average survival >15 years.
2) Trisomy 12
- 15-20%
- Associated with atypical morphology.
- Shorter treatment free survival.
3) Del(11q)
- 20-25%.
- Shorter time to progression.
4) Del(17p)
- 5- 10%
- Associated with unmutated IGHV, TP53 mutations, clonal evolution, complex karyotype.
- Associated with resistance to chemotherapy.
List the Rai and Binet stages in CLL
Rai staging: Stages 0-IV - 0= isolated lymphocytosis - 1= + lymphadenopathy - 2= and/or spleen/liver - 3= and/or anaemia - 4= and/or thrombocytopenia OS ranges from >15yrs to 3-5yrs.
Binet staging:
- A isolated lymphocytosis
- B >3 lymphoid areas
- C anaemia/ thrombocytosis
How is a diagnosis of atypical CLL made?
- Atypical morphology: cleaved forms, prolymphocytes, large/ immature cells present and comprise >15% of total lymphocytes.
- Atypical immunophenotype: can be CD5-, CD23-, Sig+ (strong) and FMC7+. Usually CD200 positive.
- Associated with trisomy 12
What is grade 3 follicular lymphoma?
Defined by the presence of more than 15 centroblasts per HPF
- Grade 3A: centrocytes also present.
- Grade 3B: centrocytes absent
Ki67 often >20%
What are the hallmark features of follicular lymphoma?
How do these features differ across the different grades of follicular lymphoma?
- Germinal centre B cell that has undergone VDJ rearrangement
- BCL2 over-expression with t(14;18) in 85-90%
- CD10 positive (rare in other small cell lymphomas)
- Aberrations in chromatin modifiers: KMT2D, CREBBP, EZH2
- Grade 3 follicular lymphoma, especially grade 3B, is more likely to be CD10-, BCL2-, MUM1/IRF4+ and BCL6+ than grade 1/2 FL
List the prognostic features of follicular lymphoma
- FLIPI: age >60, Hb <120, stage III or IV, >4 nodal sites, raised LDH
- Grade 3 disease
- Aberrations in TP53, MYC translocations.
List the 4 subtypes of follicular lymphoma and the important features of these subtypes
1) Testicular follicular lymphoma
- Children and young adults
- Cytologically high grade (usually 3A)
- Lack t(14;18)
2) In situ follicular neoplasia
- Colonisation of germinal centres by B cells with t(14;18)
- If incidentally found: <5% risk of progression to FL
- Higher rates of progression if there are high numbers of FL like cells in the PB.
3) Duodenal type follicular lymphoma
- t(14;18) present within clonal B cells
- Low grade with few centroblasts present
- Good prognosis
4) Paediatric FL
- Children and young adults
- Head and neck lymph nodes. Single site of disease common
- Lack t(14;18)
- Appear high grade, high proliferation rate
- Excellent prognosis
Marginal zone lymphoma can be a diagnosis of exclusion. List the flow cytometry and immunohistochemical markers that can be performed to exclude other low grade LPDs.
- Flow cytometry: CD5-, CD10-, CD23-, CD200-, CD103-. Strong expression of SIg and the B cell markers.
- IHC: BCL6-, CCND1-, SOX11-, LEF1- and annexin A1 negative.
Discuss the genetic profile of MALT
- IGHV rearranged
- Biased IGHV gene usage
- Chromosomal translocations involving involving MALT1 on chromosome 18 and IgH on chromosome 14 are present in a subset
- t(11;18): chimeric protein BIRC3-MALT1
- t(1;14): transcriptional deregulation of BCL10
- t(14;18): transcriptional deregulation of MALT1
- t(3;14); transcriptional deregulation of FOXP1
