WHO Classification of Haematopoietic and Lymphoid Tumours, 5th Edition (2022) & ICC 2022 · Hematological Pathology Reference
Classification per WHO Classification of Haematopoietic and Lymphoid Tumours (5th ed., 2022) and ICC 2022. Click any entity card to jump to its immunophenotype.
| Entity | Lineage / Ig | Flow Cytometry Key Markers | IHC Key Markers | Critical Molecular / Genetics |
|---|---|---|---|---|
| Precursor B-cell Neoplasms | ||||
| B-ALL/B-LBL, NOS | Precursor B-cell (pre-B / pro-B) |
TdT+CD19+CD10+CD22+cCD79a+CD20±CD34±sIg−MPO−
⚑ CD10 may be dim or absent in certain genetic subtypes — always check TdT+cCD79a
|
TdT+PAX5+CD10+CD19+CD20 dim/−
★ PAX5 is the most reliable B-lineage marker on IHC — weaker than in mature B-cells
|
IG gene rearrangement (clonal) · IKZF1 del · CDKN2A/B del · PAX5 del · No defining recurrent lesion by definition |
| Ph+ B-ALL (BCR::ABL1) | Precursor B-cell |
TdT+CD19+CD10+CD25+CD34+sIg−
★ CD25 coexpression on blasts is a useful surrogate marker for BCR::ABL1 before FISH results
|
TdT+PAX5+CD25+
★ Confirm with FISH for t(9;22) and RT-PCR for BCR::ABL1 transcript type (p190 vs p210)
|
t(9;22)(q34.1;q11.2) · p190 BCR::ABL1 most common in ALL (vs p210 in CML) · IKZF1 del (Ikaros) in most · TKI-sensitive (imatinib/dasatinib/ponatinib) · poor prognosis without TKI |
| Ph-like B-ALL | Precursor B-cell |
TdT+CD19+CD10 low/−CD34+CD25±
⚑ No unique immunophenotype — must test with RNA sequencing or targeted fusion panel
|
TdT+TSLPR (CRLF2) IHC+BCR::ABL1−
★ CRLF2/TSLPR IHC overexpression signals JAK-pathway Ph-like subtype — treat with JAK inhibitors
|
CRLF2 rearrangement (~50% Ph-like) · JAK1/JAK2 mut · EPOR fusions · ABL-class fusions (ABL1, ABL2, PDGFRA/B, CSF1R) · IKZF1 del · NTRK3 fusions · actionable with TKI/JAK inhibitors |
| B-ALL with ETV6::RUNX1 | Pre-B (cytoplasmic IgM+) |
TdT+CD19+CD10++ (bright)CD34+CD9−cIgM−/low
★ CD10 very bright + CD9 negative pattern on flow is suggestive of ETV6::RUNX1
|
TdT+CD10+CD9−
★ Late relapses (5–10 yrs) occur — may arise from persisting pre-leukemic clone
|
t(12;21)(p13.2;q22.1) · ETV6::RUNX1 fusion (TEL-AML1) · FISH or RT-PCR required (cryptic on standard karyotype) · Excellent prognosis ~90% OS · Secondary genetic hits at relapse: ETV6 del, CDKN2A del |
| B-ALL with KMT2A rearrangement | Pro-B (no cIgM) |
TdT+CD19+CD10−CD15+NG2 (7.1)+CD65+CD9+
⚑ CD10− pro-B phenotype in infant mimics ALL of ambiguous lineage — always check NG2 and FISH for KMT2A
|
TdT+CD10−CD15+NG2+ | KMT2A (MLL) rearrangement · >80 fusion partners · t(4;11) AFF1::KMT2A most common in infants · t(9;11) MLLT3 most common in children · FLT3 ITD at relapse · Very poor prognosis in infants |
| B-ALL with DUX4 rearrangement | Precursor B-cell |
TdT+CD19+CD10±CD2+CD371 (CLL-1)+
★ CD2 + CD371 (CLL-1) coexpression on B-cell blasts is characteristic of DUX4-rearranged ALL
|
TdT+PAX5+ERG del (FISH/IHC)
★ ERG deletion is nearly universal in DUX4::IGH ALL and has favorable prognostic impact
|
DUX4::IGH rearrangement · ERG deletion (co-occurring, favorable) · Excellent prognosis despite Ph-like gene expression · Adolescents and young adults |
| B-ALL with hyperdiploidy | Precursor B-cell · pre-B |
TdT+CD19+CD10++ brightCD34+CD20±sIg−
★ CD10 tends to be very bright — one of the brightest CD10 expressions among B-ALL subtypes
|
TdT+CD10++ brightPAX5+ | >50 chromosomes · Trisomies 4, 10, 17 (best prognosis subset) · ETV6 del common · KRAS/NRAS · FLT3 · Excellent prognosis (~90% OS) · Children 1–10y · Absent in adults |
| B-ALL with hypodiploidy | Precursor B-cell |
TdT+CD19+CD10±CD34±
⚑ No unique immunophenotype — cytogenetics (SNP array/karyotype) required to classify; near-haploid worst
|
TdT+PAX5+
★ Near-haploid (<30 chr): IKZF2/3 deletions, CDKN2A/B del, RAS pathway · Low-hypo (31–39): RB1/TP53/IKZF2 · Very poor prognosis
|
<46 chromosomes · Near-haploid (<30) worst subtype · TP53 mut (low-hypodiploid) · IKZF2 del · RB1 del · CDKN2A del · Allogeneic SCT in CR1 for near-haploid |
| B-ALL with TCF3::PBX1 | Pre-B (cytoplasmic IgM+) |
TdT+CD19+CD10+ (dim)cIgM+ (cytoplasmic)CD9+sIg−
★ Pre-B (cIgM+, sIg−) phenotype with dim CD10 should prompt FISH/RT-PCR for TCF3::PBX1
|
TdT+cIgM+CD10 dimPAX5+ | t(1;19)(q23;p13.3) · TCF3::PBX1 (E2A-PBX1) · Standard-risk intensified therapy · Intermediate prognosis · Associated with CNS relapse — CSF prophylaxis important |
| B-ALL with IGH::IL3 | Precursor B-cell · eosinophilic context |
TdT+CD19+CD10+CD34±
★ Reactive eosinophilia and basophilia in PB smear alongside blasts = clue to IGH::IL3 (IL-3 drives eosinophil production)
|
TdT+PAX5+CD10+ | t(5;14)(q31.1;q32.3) · IGH::IL3 · IL-3 overexpression → reactive eosinophilia (may mimic hypereosinophilic syndrome) · Rare (~1% B-ALL) · Variable prognosis · May present with organomegaly from eosinophil infiltration |
| B-ALL with iAMP21 | Precursor B-cell |
TdT+CD19+CD10+CD34±sIg−
⚑ No unique flow immunophenotype — iAMP21 is defined purely by cytogenetics (≥5 extra RUNX1 copies); cannot diagnose by phenotype alone
|
TdT+PAX5+CD10+
★ FISH for RUNX1 showing ≥5 extra signals (iAMP21) is mandatory — standard R-banding karyotype may miss this; SNP array or specific FISH probe required
|
Intrachromosomal amplification of chromosome 21 (iAMP21) · ≥5 extra RUNX1 signal copies · Older children/adolescents (median ~10y) · Poor with standard therapy · Requires intensified (augmented BFM) treatment · 14–17% of pediatric B-ALL in older cohorts |
| B-ALL with MEF2D rearrangement | Precursor B-cell · pre-B |
TdT+CD19+CD10 low/−cIgM+CD34−
★ CD10 low or negative with cIgM+ pre-B phenotype in older child/adult + negative for other translocations → prompt MEF2D fusion testing
|
TdT+PAX5+CD10 low/−
★ HDAC inhibitors may have activity (MEF2D pathway) · RNA sequencing preferred for fusion detection
|
MEF2D::BCL9 (most common) · other MEF2D fusions (HNRNPUL1, SS18, FOXJ2) · Intermediate–poor prognosis · Older children and adults · HDAC inhibitor sensitivity in vitro · Defined by RNA sequencing |
| B-ALL with ZNF384 rearrangement | Precursor B-cell · myeloid antigen coexpression |
TdT+CD19+CD10 low/−CD13+ and/or CD33+CD34±
⚑ Myeloid antigen coexpression (CD13/CD33) can mimic mixed-phenotype acute leukemia (MPAL) — assess blast lineage carefully; TdT+/PAX5+ confirms B-lineage commitment
|
TdT+PAX5+CD10 low/−CD13/CD33+
★ ZNF384 fusions are uniquely associated with B-ALL that expresses myeloid antigens without meeting MPAL criteria — fusion testing resolves ambiguity
|
EP300::ZNF384 (most common) · TCF3::ZNF384 · CREBBP::ZNF384 · Intermediate prognosis · CD10 low/absent despite B lineage · Myeloid co-expression is hallmark · Defined by RNA sequencing or targeted fusion panels |
| B-ALL with PAX5 alteration | Precursor B-cell |
TdT+CD19+CD10 dim/−CD34±
★ PAX5 P80R hotspot: dim CD10 on flow; phenotype mimics ETP-ALL or Ph-like — PAX5 sequencing/IHC intensity helps (PAX5 P80R → weaker PAX5 IHC staining in some)
|
TdT+PAX5 dim/mut+CD10 dim/−
★ PAX5 P80R is the most common PAX5 hotspot mutation in B-ALL; associated with germline CDK6 in some pedigrees. PAX5 fusions (PAX5::ETV6, PAX5::FOXP1, etc.) are distinct from PAX5 P80R
|
PAX5 P80R missense mutation (most common) · PAX5 fusion (PAX5::ETV6, PAX5::NOL4L, PAX5::FOXP1 etc.) · PAX5 amplification · CDKN2A/B del · Variable prognosis depending on alteration type · New WHO 5 entity — grouped by PAX5 pathway disruption |
| Mature Small B-cell Lymphomas / Leukemic | ||||
| CLL / SLL | Mature B-cell · surface IgM/IgD dim |
CD5+CD23+CD19+CD20 dimFMC7−CD10−sIg dim (κ or λ)CD200+CD79b dim/−
⚑ Matutes score (0–5): CLL = 4–5; lower scores → investigate for MCL, MZL, LPL
|
CD5+CD23+CD20 dimBCL2+CyclinD1−LEF1+CD200+
★ LEF1 and CD200 are the best IHC markers to distinguish CLL from MCL (CyclinD1−) and other CD5+ B-cell lymphomas
|
TP53 del/mut (high risk) · del(17p), del(11q), trisomy 12, del(13q) · IGHV unmutated = worse prognosis · ZAP70+ = surrogate for IGHV unmutated · BTK/PLCG2 resistance mutations · Richter transformation → DLBCL |
| Hairy cell leukemia | Mature B-cell · IgM+ IgG+ IgD− |
CD11c++ (bright)CD25+CD103+CD19+CD20++CD5−CD10−CD23−
★ CD11c++ CD25+ CD103+ = classic HCL triad on flow; all three together virtually diagnostic
|
Annexin A1+CD25+CD103+DBA.44+CD20++ brightCD5−
★ Annexin A1 is the most specific IHC marker for HCL — absent in HCL-variant and SDRPSBCL
|
BRAF V600E (virtually 100% of classic HCL) · MAP2K1 mut in BRAF-WT cases (variant) · Vemurafenib (BRAF inhibitor) for refractory · Excellent prognosis with cladribine/pentostatin |
| SMZL | Mature B-cell · IgM+ (biclonal villinous) |
CD19+CD20+CD5−CD10−CD23−CD103−CD25−sIgM+
⚑ Phenotype of SMZL is non-specific — diagnosis requires integration of morphology, BM/spleen histology, and molecular testing
|
CD20+CD5−CyclinD1−CD10−BCL2+Annexin A1− | del(7q31-32) (~40%) · NOTCH2 mut (~20%) · KLF2 mut · IGHV1-2*04 usage · HCV association · Splenectomy ± rituximab |
| LPL / Waldenström | B-cell → plasmacytoid → plasma cell continuum · IgM M-protein |
CD19+CD20+CD22±CD25+CD5−CD10−CD23−CD138+ (plasma cell component)
★ Flow shows admixture of B-cells, plasmacytoid lymphocytes, and plasma cells — all related clonal
|
CD20+CD138+ (PC)IgM+CD5−CD10−
★ MYD88 L265P allele-specific PCR on BM is the key molecular test — positive in >90%
|
MYD88 L265P (>90%) · CXCR4 mut (~30%) · CD79B mut (subset) · Highly specific for LPL when all three present · CXCR4 mut = worse prognosis, ibrutinib resistance · IgM MGUS precursor |
| SBLPN (formerly B-PLL / HCL-V) | Mature B-cell · IgM+ (villinous morphology) |
CD19+CD20++CD11c+CD123+CD25−CD103−CD5−
⚑ CD103−/Annexin A1− distinguishes from classic HCL — morphology alone cannot separate
|
CD20++ brightAnnexin A1−CD25−DBA.44+ | CCND3 mut (WHO 5 SBLPN subset) · No BRAF V600E · TP53 mut · 17p del · IGHV4-34 usage (SDRPSBCL component) · Worse prognosis than classic HCL |
| Follicular Lymphomas, MZL, and Related | ||||
| Follicular Lymphoma (Gr 1–2, 3A, 3B) | Germinal center B-cell · sIgM/IgG+ |
CD10+BCL2+ (dim–mod)CD19+CD20+BCL6+CD5−CD23 dim/−MUM1−
⚑ BCL2− does not exclude FL — Grade 3B FL and pediatric FL are often BCL2 translocation-negative
|
CD10+BCL2+BCL6+MUM1/IRF4−Ki-67 low–mod (Gr 1–2), high (3B)
★ CD10 + BCL2 coexpression in follicles = FL; BCL2+ in germinal center cells is always abnormal
|
t(14;18)(q32;q21) → BCL2::IGH (~85% Gr1-2) · EZH2 hotspot mut (GCB) · CREBBP/EP300 · KMT2D · TNFRSF14 · Grade 3B: BCL6 translocation ± · High Ki-67 + CD10 loss → transformation risk |
| MALT lymphoma (Extranodal MZL) | Mature B-cell · marginal zone · IgM/IgA+ |
CD19+CD20+CD5−CD10−CD23−CyclinD1−CD43± (site-dependent)
⚑ No single pathognomonic immunophenotype — diagnosis requires morphology + site + exclusion of other small B-cell lymphomas
|
CD20+CD5−CD10−CyclinD1−BCL10+ (cytoplasmic/nuclear in translocations)
★ BCL10 nuclear expression (IHC) indicates t(1;14) or t(14;18)(q32;q21) MALT1 translocation — predicts antibiotic non-response
|
t(11;18)(q21;q21) BIRC3::MALT1 (~25%, gastric antibiotic-resistant) · t(1;14)(p22;q32) BCL10::IGH · t(14;18)(q32;q21) IGH::MALT1 · Site-specific translocations: t(3;14) FOXP1 (thyroid) · H. pylori (gastric) · MALT1 pathway (NF-κB) |
| Nodal MZL (NMZL) | Mature B-cell · marginal zone · sIgM+ | CD19+CD20+CD5−CD10−CD23−CD43± |
CD20+CD5−CD10−CyclinD1−CD21+ (FDC)
★ Monocytoid B-cell appearance in perisinusoidal/perifollicular distribution — always confirm no systemic MZL
|
PTPRD mut · KLF2 mut · TNFAIP3 mut · MLL2/KMT2D · No specific translocation · Diagnosis of exclusion (no extranodal/splenic involvement) |
| MCL (classical & leukemic types) | Mature B-cell · naive/mantle zone · IgM/IgD+ |
CD5+CD23−CD19+CD20++ brightFMC7+CD200−CD10−
★ CD5+ CD23− FMC7+ CD200− = MCL pattern on flow; CD200 negativity is the key distinction from CLL
|
CyclinD1+SOX11+CD5+CD20+BCL2+CD10−
★ CyclinD1 is the hallmark — SOX11 negative in leukemic non-nodal (indolent) MCL. Blastoid/pleomorphic variants: CyclinD1+ SOX11+, high Ki-67, TP53 mut
|
t(11;14)(q13;q32) · CCND1::IGH (virtually 100%) · TP53 mut/del (poor) · ATM mut/del · CDKN2A del · SMARCA4 (blastoid) · SOX11+ = aggressive · IGHV mutated + SOX11− = indolent leukemic MCL |
| Diffuse Large B-cell Lymphomas | ||||
| DLBCL, NOS — GCB subtype | Germinal center B-cell · sIgM/IgG+ | CD10+CD19+CD20+BCL6+MUM1/IRF4−BCL2± (if BCL2 translocation) |
CD10+ and/or BCL6+/MUM1−CD20+BCL2±MYC protein ≥40%
★ Hans algorithm: CD10+ → GCB; CD10− BCL6+ MUM1− → GCB; CD10− BCL6− or MUM1+ → non-GCB/ABC
|
EZH2 hotspot (Y641) · BCL2 t(14;18) (~30%) · MYC rearrangement (subset → DHL) · CREBBP · KMT2D · GNA13 · SGK1 · GCB gene expression signature (COO by Nanostring/RNA-seq) |
| DLBCL, NOS — ABC/non-GCB subtype | Post-GC / activated B-cell · IgM/IgG+ | CD10−CD19+CD20+MUM1/IRF4+BCL6±BCL2+ (often) |
MUM1/IRF4+CD10−BCL2+MYC protein ≥40%
★ MYD88 L265P + CD79B mut = "MCD subtype" (ABC) — targetable with BTK inhibitors · CNS predilection
|
MYD88 L265P · CD79B mut (MCD subtype) · CARD11 mut (BCL10-MALT pathway) · BLIMP1/PRDM1 del · BCL2 amplification · IRF4 amplification · Worse prognosis with R-CHOP vs GCB |
| HGBCL with MYC + BCL2 rearrangements | GCB germinal center B-cell · IgM/IgG+ |
CD10+BCL6+MUM1−BCL2++ (bright on flow)MYC protein ≥40%
⚑ Flow/IHC protein expression does NOT predict MYC rearrangement — FISH for MYC is mandatory in all DLBCL
|
MYC IHC ≥40%+BCL2 IHC ≥50%+CD10+BCL6+MUM1−
★ "Double expresser" (IHC MYC≥40%+BCL2≥50%) ≠ DHL — FISH must confirm rearrangements for this entity
|
MYC rearrangement + BCL2 t(14;18) rearrangement (mandatory by definition) · IGH partner MYC in ~70% · Non-IG partner MYC = less certain prognosis impact · CNS prophylaxis required · DA-R-EPOCH preferred over R-CHOP |
| T-cell/histiocyte-rich large B-cell lymphoma | GCB B-cell (sparse large cells) |
CD19+CD20+CD10±BCL6+CD15−CD30−/dim
⚑ Neoplastic B-cells are sparse — may be missed on flow; IHC on biopsy is essential
|
CD20+ (sparse large cells)BCL6+EBV EBER−background CD3+/CD8+ T-cellsCD68+ histiocytes
★ EBV− is critical to differentiate from NLPBL (EBV−, LP cells) and EBV+ DLBCL — use EBER ISH
|
EZH2 mut · CREBBP · GCB-like gene expression · BCL2 t(14;18) in some · Overlap with nodular NLPBL · No CD15/CD30 (unlike cHL) |
| Primary Mediastinal LBCL | Thymic B-cell · sIg−/weak |
CD19+CD20++CD30+ (weak/heterogeneous)sIg−/dimCD10−
⚑ CD30 weak and heterogeneous (unlike cHL where RS cells are strongly CD30+) — combined with clinical context
|
CD20++CD30+ (weak)MAL+PDL1/PDL2+CD15−sIg−
★ MAL expression is highly specific for PMBL · PDL1/PDL2 (9p24.1 amp/gain) = checkpoint therapy target · Pembro now approved
|
9p24.1 amplification → JAK2 + PDL1/PDL2 overexpression · REL amplification · STAT6 · TNFAIP3 · IL4R · Molecular similarity to NSHL (cHL) · distinct from DLBCL-NOS · Pembrolizumab approved relapsed PMBL |
| Primary CNS DLBCL (PCNSL) | ABC/non-GCB · IgM/IgG+ |
CD19+CD20+CD10−MUM1+BCL6+
⚑ CSF flow cytometry low sensitivity; vitreoretinal involvement may be amenable to aqueous humor flow cytometry
|
MUM1/IRF4+BCL6+CD10−BCL2+MHCII lost
★ MHC class II (HLA-DR) loss by IHC is characteristic of PCNSL — immune evasion mechanism
|
MYD88 L265P (60–80%) · CD79B mut (~60%) · BCL6 translocation · CDKN2A del · MHC class II (B2M/CIITA) mutations · High-dose MTX-based regimens · No R-CHOP · Autologous SCT consolidation |
| Primary cutaneous DLBCL, leg type | ABC/non-GCB · IgM/IgG+ | CD19+CD20+CD10−MUM1++ (strong)BCL2++ (strong) |
MUM1++ strongBCL2++ strongCD10−BCL6±CD5−
★ MUM1++ and BCL2++ in a cutaneous large B-cell lymphoma on the legs of an elderly woman = PCDLBCL-LT until proven otherwise
|
MYD88 L265P (60–70%) · CD79B · CDKN2A del · MYC amp · BLIMP1/PRDM1 del · Worse prognosis than pcFCBCL · R-CHOP required (not RT alone) |
| EBV+ DLBCL, NOS | Post-GCB · IgM/IgG+ | CD19+CD20+CD30+ (often)CD15±MUM1+ |
EBER ISH+LMP1+CD30+CD15±CD20+
★ EBER ISH is mandatory for diagnosis — LMP1 alone may be negative (latency I/II). Elderly patients; immunosenescence background
|
EBV+ (latency III: EBNA2, LMP1, LMP2) · PDL1 overexpression · Geographic variation (higher in Asia, Latin America) · Better response to R-CHOP vs expected; checkpoint inhibitor benefit emerging |
| EBV+ mucocutaneous ulcer | EBV+ B-cell (RS-like large cells) |
CD20+CD30+CD15±
★ Self-limited — may resolve if immunosuppression reduced. Do not over-treat
|
EBER ISH+CD30+CD20+CD15±Systemic involvement absent
★ Distinct from EBV+ DLBCL NOS by: (1) mucosal/cutaneous only, (2) circumscribed base, (3) iatrogenic/immunosuppression context, (4) benign lymphoid background at margins
|
EBV+ · Iatrogenic immunosuppression (MTX, azathioprine, anti-TNF) · Also HIV · Elderly · Localized · Excellent prognosis with dose reduction/withdrawal |
| Intravascular LBCL | Mature B-cell · ABC phenotype |
CD19+CD20+CD5−MUM1+
⚑ Blood/BM flow cytometry often negative — diagnosis requires random skin/organ biopsy
|
CD20+MUM1+CD29 (integrin β1)−CD54 (ICAM-1)−
★ Loss of CD29/CD54 (homing receptor) explains why cells remain in vessels — IHC on random skin punch biopsy is the fastest diagnostic route
|
MYD88 L265P · CD79B · ABC/non-GCB gene expression · HLH in Asian variant · CNS involvement common · R-CHOP + CNS prophylaxis |
| Plasmablastic lymphoma | Plasmablastic · switched/mutated Ig · cIg+ |
CD20−CD19−CD138+CD38++CD45+cIg+
⚑ CD20-negative large B-cell lymphoma — do not misclassify as non-B-cell neoplasm; check CD138/CD38
|
MUM1/IRF4++ strongCD138+CD20−EBER ISH+ (~70%)Ki-67 ~100%
★ MYC IHC nearly always positive (≥80%); EBER+ in ~70%; HIV+ context most common in Western countries; EBV+ in oral cavity lesions
|
MYC rearrangement (~50%) · EBV+ (~70%) · HIV association · IGHV mutated (class-switched) · PRDM1/BLIMP1 · NRAS/KRAS mut · CD20− precludes rituximab monotherapy · Poor prognosis |
| Primary effusion lymphoma | Plasmablastic / null phenotype · cIg variable |
CD45+CD20−CD19−CD138±CD38+sIg−
⚑ "Null" B-cell phenotype — HHV8 LANA-1 IHC on cytologic cell block is essential for diagnosis
|
LANA-1 (HHV8) IHC+EBER ISH+ (~70%)CD20−CD138±CD45+ | HHV8+ (KSHV) · EBV+ in ~70% · HIV-associated · Serous cavities (pleura, pericardium, peritoneum) · IG genes rearranged (clonal) · NF-κB / JAK-STAT driven · Poor prognosis median survival <6 months |
| Fluid overload-associated LBCL | Plasmablastic B-cell · cIg+ |
CD20−CD138+CD38+HHV8 (LANA1)−
★ Key distinction from PEL: HHV8-negative and EBV-negative in most cases
|
LANA-1−EBER ISH− (most)CD138+CD20−
★ NEW WHO 5 entity — effusion lymphoma in setting of chronic inflammation/cardiac failure WITHOUT HHV8 or EBV
|
HHV8− · EBV− (most) · Context of chronic inflammation/cardiac failure/hepatitis · IG rearrangement (clonal) · Distinct from PEL · Prognosis intermediate |
| ALK+ large B-cell lymphoma | Plasmablastic B-cell · IgA+ common |
CD20−CD19−CD138+ALK+EMA+
⚑ ALK+ large B-cell lymphoma must be distinguished from ALK+ ALCL (T-cell) — CD138, IgA, absence of T-cell markers
|
ALK+ (granular cytoplasmic)EMA+CD138+IgA+CD20−CD30−
★ ALK pattern = granular cytoplasmic (CLTC fusion) or nuclear+cytoplasmic (NPM fusion) · IgA light chain restriction common
|
CLTC::ALK most common · NPM1::ALK (minority) · CLTC::ALK → granular cytoplasmic ALK pattern · ALK TKI (crizotinib) may be effective · Sinusoidal distribution in lymph nodes |
| Lymphomatoid granulomatosis (LyG) | EBV+ B-cells in T-cell background |
CD20+ (large EBV+ cells)CD5−
⚑ Flow cytometry is of limited value — tissue biopsy essential; large EBV+ B-cells are the neoplastic component
|
EBER ISH+ (large cells)CD20+ (large cells)background CD3+/CD8+ T-cells
★ Grade 1/2: EBV+ B-cell clusters in T-cell background, angiocentric; Grade 3: confluent sheets of large B-cells = frank DLBCL
|
EBV+ (latency II/III) · Immunodeficiency background (HIV, Wiskott-Aldrich, post-transplant) · JAK3 mut (Grade 3) · Angiocentric/angiodestructive pattern in lung · Grade 1–2: IFN-α2b; Grade 3: R-CHOP |
| Burkitt Lymphoma | ||||
| Burkitt lymphoma | GCB mature B-cell · IgM+ surface |
CD10++CD19+CD20+BCL6+BCL2− (key!)TdT−CD5−
⚑ BCL2− helps distinguish from HGBCL-DHL (BCL2+) — but BCL2+ does NOT exclude BL in children; always confirm with FISH MYC (not BCL2)
|
Ki-67 ~100%BCL2− (classic)CD10+BCL6+MYC IHC ≥80%EBER ISH+ (endemic ~100%, sporadic ~30%)
★ Ki-67 approaching 100% + BCL2− + CD10+ + MYC ≥80% protein = classic Burkitt IHC profile
|
MYC rearrangement t(8;14) or t(8;22) or t(2;8) (mandatory) · IGH::MYC (80%) · ID3 / TCF3 / CCND3 mut (somatic hypermutation) · TET2 · TP53 (worse prognosis) · EBNA1 latency (endemic) · Intensive regimens: CODOX-M/IVAC, HyperCVAD, DA-EPOCH-R |
| Burkitt-like lymphoma with 11q aberration | GCB mature B-cell · IgM+ |
CD10+BCL6+BCL2−/lowMYC rearrangement−
★ Identical phenotype to BL but lacks MYC rearrangement — always FISH for MYC before diagnosing BL; if negative, assess 11q
|
CD10+Ki-67 high (~95%)EBER ISH−MYC FISH− | 11q gain (proximal) + 11q loss (distal) · No MYC rearrangement · Nodal-predominant · Young adults · Possibly better prognosis than BL · WHO 5 distinct provisional entity |
| Plasma Cell Neoplasms | ||||
| Plasma cell myeloma / MM | Terminally differentiated B-cell · monoclonal cIg+ |
CD138+CD38++cIg+ (κ or λ restricted)CD19−CD45− (mature MM)CD56+CD117±CD20−
★ Normal plasma cells: CD19+CD45+CD56−; MM plasma cells: CD19−CD45−CD56+ — use this inversion on multiparameter flow for MRD
|
CD138+CD38++MUM1/IRF4+cIg κ or λ restrictedCD20−PAX5−
★ PAX5 is NEGATIVE in MM (differentiates from B-LBL) · MUM1/IRF4 positive in MM
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t(11;14) → CCND1 (standard risk, venetoclax-sensitive) · t(4;14) → FGFR3/MMSET (high risk) · t(14;16) → MAF (high risk) · del(17p)/TP53 (very high risk) · del(1p)/1q gain · KRAS/NRAS/BRAF · Hyperdiploidy (standard risk) · MRD by next-gen flow or NGS |
| POEMS syndrome | Plasma cell · monoclonal λ cIg (virtually always) |
CD138+CD38+λ light chain (virtually 100%)κ chain−
★ λ restriction is essentially universal in POEMS — κ restricted M-protein should prompt reconsideration of diagnosis
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CD138+λ restrictedVEGF serum markedly elevatedSclerotic bone lesions | VEGF markedly elevated (serum) · t(11;14) in subset · Sclerotic bone lesions / Castleman disease-like LN · No del17p · POEMS criteria: Polyneuropathy + Organomegaly + Endocrinopathy + M-protein + Skin changes (POEMS) + Papilledema · SCT for eligible |
| Hodgkin Lymphoma (B-cell Derived) | ||||
| NLPBL (formerly NLPHL) | GCB B-cell (LP / popcorn cells) |
CD20++CD19+CD45+CD15−CD30− (weak/absent)EBV−
⚑ CD20++ + CD45+ + EBV− in HL-morphology = NLPBL; CD20 weak/dim + CD15/CD30+ = cHL RS cells — critical distinction
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CD20++ strongOCT2+BOB1+CD45+BCL6+CD15−CD30 weak/−EBER ISH−
★ OCT2+/BOB1+ (both positive) is the hallmark of NLPBL; in cHL, OCT2 may be + but BOB1 is typically negative — this distinction is critical
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IGHV mutated (GCB origin) · BCL6 rearrangement (~25%) · SGK1 · DUSP2 · No EBV · STAT6 JAK pathway · Indolent; late relapses; transforms to THRLBCL (or rarely DLBCL) · Rituximab-responsive |
| Classical Hodgkin lymphoma (all subtypes: NSHL / MCHL / LRHL / LDHL) | B-cell (RS cell) — lost B-cell program |
CD20 weak/−CD19−CD30++ (RS cells)CD15+CD45−EMA−
⚑ Classic RS cells rarely circulate; flow cytometry has no role in primary diagnosis — tissue biopsy is mandatory
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CD30++ (membranous+Golgi)CD15+CD45−CD20 weak/−OCT2 weak/−BOB1−PAX5 weak+EBER ISH+ (MCHL ~75%, NSHL ~20%, LDHL ~80%)
★ PAX5 weak+ in RS cells (vs strong+ in B-cell lymphomas) · BOB1− differentiates cHL from NLPBL · NSHL: lacunar cells · MCHL: classic RS · LDHL: numerous RS, depleted background
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9p24.1 amp → PDL1/PDL2/JAK2 (NSHL/PMBL overlap) · REL/NF-κB pathway · JAK-STAT · BCL2 expression · Somatic hypermutation in Ig V genes (non-functional rearrangements) · EBV latency II (MCHL > NSHL) · Pembrolizumab/nivolumab approved for relapsed cHL |
Purple border = hallmark/discriminating marker · Green = positive · Red-orange = negative · Amber = variable/partial
| Entity | Architecture & Growth Pattern | Cytology (Cell Morphology) | Key Diagnostic Features | Pitfalls / Must Not Miss |
|---|---|---|---|---|
| Precursor B-cell Neoplasms | ||||
| B-ALL / B-LBL | BM: diffuse replacement by blasts · Starry-sky pattern (macrophages) · LBL: diffuse effacement ± mediastinal mass (less common than T-LBL) · Marrow aspirate: monotonous blasts | Medium-sized blasts · Fine granular ("powdery") chromatin · Small or absent nucleoli · Scant cytoplasm · High N:C ratio · Brisk mitoses · Apoptotic bodies · NO cytoplasmic granules (helps distinguish from AML) |
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⚑ Mimics AML — TdT, CD19, PAX5 distinguish; ETP-ALL has myeloid markers → overlap ⚑ Lymphoid aggregates in BM (normal/reactive) mistaken for infiltrate — use TdT IHC to confirm blasts |
| Small B-cell Lymphomas / Leukemic | ||||
| CLL / SLL | SLL: diffuse paracortical/interfollicular pattern · Proliferation centers (pseudofollicles) = pathognomonic · BM: nodular, interstitial, or diffuse · PB: small lymphocytosis | Small, round mature lymphocytes · Dense, clumped chromatin ("soccer ball") · Scant cytoplasm · Occasional prolymphocytes within proliferation centers · Smudge/basket cells in PB smear (fragile cells) |
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⚑ Activated/large proliferation centers can mimic DLBCL — always look for surrounding classic small CLL cells ⚑ BM nodular pattern without IHC can be mistaken for reactive lymphoid aggregates — CD20/CD5/LEF1 IHC |
| Hairy cell leukemia | BM: diffuse to interstitial · "Fried egg" pattern: evenly-spaced cells with wide clear halos · "Dry tap" on aspiration (fibronectin mesh) · Spleen: red pulp expansion · "Blood lakes" in spleen | Medium-sized cells · Abundant pale cytoplasm · Irregular, "hairy" cytoplasmic projections (villous) · Kidney-shaped or oval nucleus · Inconspicuous nucleolus · "Fried egg" spacing |
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⚑ BM may appear hypocellular — the wide halos can create false impression of empty marrow at low power ⚑ HCL-V / SBLPN: similar hairy morphology but NO Annexin A1, NO BRAF V600E — always check these |
| SMZL | Spleen: white pulp expansion with marginal zone differentiation · Mantle zone replaced by pale marginal-zone B-cells · Red pulp infiltration · BM: interstitial/sinusoidal | Small-to-medium cells · "Biphasic" appearance: central small lymphocytes + surrounding pale marginal zone cells · Short polar villi (villous lymphocytes) in PB · Plasmacytoid differentiation in some |
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⚑ Morphologically overlaps with LPL, HCL-V, NMZL — immunophenotype + genetics required to separate ⚑ PB villous lymphocytes in SMZL have SHORT polar villi (HCL has circumferential long villi) |
| LPL / Waldenström | BM: diffuse or interstitial · Mast cells increased (characteristic!) · Lymph node: interfollicular or diffuse · PB: lymphoplasmacytoid cells | Continuum of small lymphocytes → plasmacytoid lymphocytes → mature plasma cells · "Dutcher bodies" (intranuclear PAS+ Ig inclusions) · "Russell bodies" (intracytoplasmic) · Increased mast cells in BM |
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⚑ Overlaps with MZL/SMZL — MYD88 L265P positive (LPL) vs negative (most MZL) is the key molecular discriminator ⚑ Hyperviscosity (Waldenström) can occur — check IgM level; rouleaux in PB smear |
| MCL (classical) | Mantle zone, nodular, or diffuse patterns · Effacement with pale "mantle zone" concentric growth · Hyalinized vessels · Naked germinal centers (surrounded by MCL cells) · Blastoid/pleomorphic variant: diffuse sheets | Monomorphic small-to-medium cells · Slightly irregular/cleaved nuclei · Condensed chromatin · Inconspicuous nucleoli · Scant pale cytoplasm · Blastoid variant: immature blast-like cells, prominent nucleoli · Pleomorphic variant: marked anisocytosis |
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⚑ Mantle zone pattern of MCL can look like reactive follicular hyperplasia at low power — always do CyclinD1 IHC on any mantle zone expansion ⚑ Blastoid MCL mimics B-ALL — TdT typically negative but dim CyclinD1+ helps; FISH for CCND1 ⚑ ISMCN: CyclinD1 strong only in inner mantle zone — expanded inner mantle zone = ISMCN, do not call lymphoma |
| Follicular Lymphomas and Related | ||||
| Follicular Lymphoma | Follicular (back-to-back follicles without mantle zones), or follicular+diffuse, or pure diffuse (rare) · Follicles poorly defined, lack polarization · Grade 1–2: predominantly centrocytes · Grade 3A: ≥15 centroblasts/HPF + centrocytes · Grade 3B: solid sheets of centroblasts | Grade 1–2: small-to-medium cleaved cells (centrocytes) · Angular, irregular, "coffee bean" nuclear clefts · Scant pale cytoplasm · Few large centroblasts · Grade 3B: large cells with prominent nucleoli, resembling DLBCL |
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⚑ Reactive follicular hyperplasia: polarized, mantle zones present, tingible body macrophages (starry-sky), BCL2− GC cells ⚑ FL Grade 3B may lack t(14;18) — behaves as aggressive lymphoma; treat with R-CHOP not watch-and-wait ⚑ ISFN: CyclinD1-negative but BCL2++ in mantle zone cells — do NOT call lymphoma; report as ISFN and stage to exclude concurrent FL |
| MALT lymphoma | Diffuse or nodular marginal zone pattern · Reactive follicles with "colonization" of germinal centers by neoplastic marginal zone cells · Lymphoepithelial lesions (LEL) · "Monocytoid" B-cell pattern in salivary glands | Small-to-medium cells · Monocytoid B-cell appearance: abundant pale cytoplasm, irregular nuclei · Centrocyte-like cells · Plasmacytic differentiation in some · Scattered large transformed cells |
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⚑ LEL are not unique to MALT — can occur in other small B-cell lymphomas infiltrating mucosal tissue; use immunophenotype to confirm ⚑ Germinal center colonization can mimic FL — CD10 (usually negative in MZL) and BCL2 staining help ⚑ Plasmacytic differentiation in MALT can mimic LPL — assess MYD88 L265P and Ig class |
| Diffuse Large B-cell Lymphomas & High-grade | ||||
| DLBCL, NOS (GCB & ABC) | Diffuse effacement of nodal architecture · Sinusoidal invasion (variant) · Angioinvasion in some · Starry-sky pattern in rapidly proliferating tumors · Bone marrow: nodular or diffuse infiltration | Large cells ≥2× size of lymphocyte nucleus · Centroblastic: large irregular nuclei, multiple nucleoli at nuclear membrane, vesicular chromatin · Immunoblastic (ABC): single central nucleolus, more cytoplasm · Anaplastic variant: pleomorphic, RS-like cells · T-cell/histiocyte-rich: sparse large B-cells in inflammatory background |
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⚑ Anaplastic DLBCL can mimic ALCL (CD30+) — check B-cell markers (CD20, PAX5) and EMA pattern ⚑ THRLBCL: neoplastic B-cells can be extremely sparse — do not call T-cell lymphoma without exhausting B-cell IHC (CD20, PAX5, OCT2) ⚑ High Ki-67 + BCL2− + CD10++ → must FISH for MYC to exclude BL or HGBCL |
| HGBCL-MYC-BCL2 ("Double hit") | Diffuse effacement · Often "blastoid" intermediate morphology · Starry-sky pattern possible (high proliferation) · May mimic BL morphologically | Intermediate-to-large cells · May be centroblastic, immunoblastic, or blastoid · Cells intermediate between DLBCL and BL · High N:C ratio in blastoid variant · Irregular nuclei · Prominent nucleoli |
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⚑ Morphology cannot distinguish DHL from DLBCL-NOS or BL — only FISH provides the diagnosis ⚑ Non-IG-partner MYC (e.g., CUX1-MYC) has less certain prognostic significance — partner matters |
| Primary mediastinal LBCL | Diffuse large B-cell infiltrate · Compartmentalizing alveolar/sclerotic fibrosis between tumor cell clusters · Clear cytoplasm of tumor cells · Thymic remnants may be present · Mimics NSHL at low power | Large cells with abundant pale-to-clear cytoplasm · Irregular lobated nuclei · Multiple small nucleoli · Compartmentalized by fine alveolar fibrosis · Multinucleated "lacunar-like" cells possible · No RS-like cells (unlike NSHL) |
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⚑ PMBL vs NSHL: PMBL = CD20++ CD15− BOB1+; NSHL = CD30++ CD15+ CD20 weak/− BOB1− ⚑ Mediastinal gray zone lymphoma: shares features of both PMBL and cHL — classified separately in WHO 5 as B-cell lymphoma unclassifiable with features intermediate between DLBCL and cHL |
| Intravascular LBCL | Large tumor cells EXCLUSIVELY within vascular lumina · Small and medium-sized vessels · All organ beds affected · No nodal involvement · Fibrin thrombi + tumor cells in vessels | Large atypical lymphoid cells within vessel lumina · Vesicular nuclei · Prominent nucleoli · Mitoses within vessels · Similar to centroblastic DLBCL cytology |
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⚑ HLH symptoms without obvious lymphoma → remember IVLBCL; skin random biopsy is diagnostic in minutes ⚑ Vessels can be collapsed or obscured — use CD31/CD34 to outline vascular spaces and confirm intravascular location of CD20+ cells |
| EBV+ DLBCL, NOS | Polymorphic or monomorphic (large cell) patterns · Geographic necrosis · Angioinvasion in some · Scattered RS-like cells possible | Polymorphic variant: spectrum from immunoblasts to RS-like cells · Mixed inflammatory background (eosinophils, plasma cells, small lymphocytes) · Monomorphic variant: sheets of large immunoblasts · RS-like cells possible (mimic cHL) |
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⚑ Polymorphic EBV+ DLBCL vs cHL: EBV+ DLBCL = CD20++ CD45+ CD15−; cHL = CD30++ CD15+ CD20 weak/− CD45− ⚑ EBVMCU can be morphologically alarming (RS-like cells) but is self-limited — depth of biopsy and circumscription differentiate from DLBCL |
| Lymphomatoid granulomatosis | Angiocentric and angiodestructive infiltrate · Geographic necrosis · Pulmonary nodules (bilateral) · Granuloma-like areas (not true granulomas) · Grade 1: rare EBV+ B-cells · Grade 3: sheet-like DLBCL areas | Polymorphic: small lymphocytes (background, dominant), plasma cells, histiocytes · Large EBV+ B-cells (neoplastic, rare to numerous depending on grade) · Necrosis within vascular walls · Angioinvasion |
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⚑ At low grade, large EBV+ B-cells are sparse — easily overlooked on H&E; systematic EBER ISH on all cases with angiocentric infiltrate in lung ⚑ "Granulomatous" appearance can mimic granulomatous infection or sarcoidosis — clinical context (immunocompromised) + EBER ISH |
| Burkitt Lymphoma | ||||
| Burkitt Lymphoma | Diffuse effacement · Classic "starry sky" pattern (tingible body macrophages scattered throughout) · Highly proliferative · No fibrous bands · No follicles · Abdominal mass (sporadic) or jaw (endemic) | Monomorphic medium-sized cells · Round nuclei (not cleaved) · Multiple (2–5) small basophilic nucleoli at or near nuclear membrane · Moderate amount of basophilic vacuolated cytoplasm ("oil droplets" in cytoplasmic vacuoles on imprints) · Countless mitoses + apoptoses |
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⚑ BL vs HGBCL-DHL: morphology can be identical — BCL2 IHC and MYC+BCL2 FISH mandatory; do NOT diagnose BL without confirming MYC rearrangement ⚑ BL vs DLBCL with Ki-67 ~100%: BL cells are round (not cleaved), uniform, with multiple small peripheral nucleoli — cytology is the first clue ⚑ BL-like 11q aberration: identical morphology and phenotype to BL but MYC FISH negative → check 11q |
| Plasma Cell Neoplasms | ||||
| Plasma cell myeloma / MM | BM: patchy or diffuse infiltration · Interstitial, nodular, or solid sheets · Trephine: plasma cell sheets replacing normal hematopoiesis · Osteolytic lesions on imaging · Plasmacytoma: extramedullary/bony mass | Mature plasma cells: eccentrically placed nucleus · "Clock-face" chromatin ("cartwheel") · Prominent perinuclear hof (Golgi) · Abundant basophilic cytoplasm · Binucleate / multinucleate forms · Plasmablastic: large cells, prominent central nucleolus · Flame cells (IgA) · Dutcher bodies (IgG/IgA) · Mott cells (Russell bodies) |
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⚑ Reactive plasmacytosis (infection, autoimmune) vs MM: reactive = paratrabecular, polyclonal, CD19+CD45+; MM = random/diffuse, monoclonal, CD19−CD45−CD56+ ⚑ Plasmablastic MM: large cells, prominent nucleoli — mimics plasmablastic lymphoma; check EBV (negative in MM) and molecular context ⚑ Crush artifact on trephine can make plasma cells resemble lymphocytes — CD138 IHC rescues diagnosis |
| Hodgkin Lymphoma | ||||
| NLPBL (formerly NLPHL) | Nodular pattern (at least partially) · Nodules defined by CD21+ FDC meshwork · Background: predominant lymphocytes and histiocytes (L&H background) · Neoplastic cells scattered within nodules · Diffuse variant: THRLBCL-like (transformation risk) | "Popcorn cells" / LP cells = large cells with multi-lobated "popcorn" nuclei · Vesicular chromatin · Multiple small nucleoli (at periphery, not central) · Absent or inconspicuous eosinophils, neutrophils, plasma cells · NO classic RS cells (no bilobed RS with eosinophilic "owl-eye" central nucleoli) |
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⚑ Diffuse pattern of NLPBL = THRLBCL territory — if >25% of biopsy is diffuse and LP cells are T/H-rich, call THRLBCL or NLPBL-like THRLBCL ⚑ NLPBL vs LRHL (cHL): NLPBL = CD20++ OCT2+ BOB1+ EBV−; LRHL = CD20 weak/− CD15+ OCT2 weak/− BOB1− EBV+ |
| Classical Hodgkin lymphoma (NSHL / MCHL / LRHL / LDHL) | NSHL: nodular pattern with broad collagen bands dividing tumor into nodules · Lacunar cells in nodules · MCHL: diffuse or vaguely nodular, no bands · LRHL: lymphocyte-rich, rare RS cells · LDHL: diffuse, abundant RS/sarcomatous variant, fibrosis (diffuse fibrosis subtype) | Classic RS cells: large binucleate cells · Prominent eosinophilic "owl-eye" nucleoli (centrally placed in each nucleus) · Abundant pale cytoplasm · Lacunar cells (NSHL): RS in retraction artifact vacuole · Mononuclear Hodgkin cells ("H cells") · "Sarcomatous" RS (LDHL) · LP cells NOT present |
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⚑ Do NOT diagnose cHL on RS-like cells alone — RS-like cells occur in DLBCL, NLPBL, EBV+ DLBCL, T-cell lymphomas. Context + phenotype (CD30++ CD15+ CD20 weak/− CD45−) is mandatory ⚑ LDHL mimics NHL (anaplastic) or carcinoma — always consider in lymphocyte-depleted spindle cell/fibrotic mediastinal/visceral biopsies ⚑ NSHL vs PMBL: collagen bands in both, but NSHL = CD15+ CD20 weak; PMBL = CD20++ CD15− |
⚑ = diagnostic pitfall requiring active exclusion · ★ = high-yield discriminating feature