Waldenstr?m macroglobulinema (ICD-O code=9761/3) is found in a significant subset of patients with lymphoplasmacytic lymphoma with BM involvement and an IgM monoclonal gammopathy of any concentration.

In Heavy Chain Diseases, intracellular Ig heavy chains are not always IgMs.

Typically IgM+, and less often IgA+ or IgG+.

IgD is positive in a minority of the cases.

IgM+/-, IgD, IgG or rarely IgA.

More frequently with Lambda than Kappa restriction.

The membrane expression of CD3 may be weak.

25% of patients coexpress CD8 with CD4, a feature almost unique to T-PLL. 15% are CD4-neg, CD8-pos.

Expression of CD94/NKG2 and KIR families of receptors can be detected in 50% or more of cases.

Uncommon variants include CD4 TCRα/β-pos cases and TCRγ/δ-pos cases. Approximately 60% of the latter express CD8, the remainder are CD4/CD8-neg.

Abnormal uniform expression of CD8 can be seen.

KIR-pos cases preferentially express activating receptor isoforms.

If TCRα/β-positive, expect dierent immunophenotype for the rest of the markers.

A CD4-pos/CD8-neg phenotype predominates in nodal cases. CD4/CD8 double positivity or double negativity is at times seen.

CD13 with heterogeneous expression.

Co-expression of CD15 and strong CD64 is characteristic of monocytic dierentiation.

CD25 is highly associated with t(9;22) B-ALL, at least in adults.

NG2 is characteristically expressed and is relatively, though not absolutely, specific.

The cortical T stage shows a double positive (CD4-pos/CD8-pos) phenotype. The medullary T stage expresses only either CD4 or CD8.

IgM+/IgD+ as for B-CLL/SLL

When t(14;18) IGH/BCL2 is present, bcl2 expression is bright

>90% of cases also express Sox-11 by IHC

MYC protein is strongly expressed due to translocation of the MYC gene to the IGH, IGK, or IGL genes.

All immunophenotypes for T-ALL/T-LBL are based on IHC and NOT flow cytometry

In AML with inv(16), CD14 and CD64 are mainly expressed by the monocytic component of this AML with myelomonocytic dierentiation, and CD16 is mainly expressed by the granulocytic component

In AML with t(15;17), CD2, CD34, and CD123 are most commonly expressed by the microgranular variant

In AML with NPM1 mutation, the immunophenotype diers between cases with prominent monocytic dierentiation and cases with prominent myeloblastic morphology (the latter often has cuplike nuclear invagination if a concurrent FLT3-ITD mutation is present)

AML with RAM phenotype, a subset of megakaryoblastic AML, expresses high-level CD56 without CD7