Diffuse Large B-Cell Lymphoma, Not Otherwise Specified (DLBCL NOS) Presenting as Multiple Subcutaneous Nodules: An Unusual Cutaneous Presentation of Systemic Disease
Table 1
Example differential diagnosis of a primarily cutaneous high-grade B-cell neoplasm with CD5 expression.
High-grade CD5+ B-cell lymphoma with primary cutaneous involvement (select diagnostic considerations and WHO 5th edition criteria)
Primary cutaneous follicle center lymphoma Essential Follicular and/or diffuse proliferation of centrocytes and admixed centroblasts B-cells with coexpression of germinal center markers (e.g., CD10 and BCL6) No extracutaneous involvement by lymphoma Desirable Localization to head or trunk Evidence of B-cell monoclonality Absent or weak BCL2 expression (usually) Lack of MUM1 expression Absence of BCL2 rearrangement (usually)
Primary cutaneous diffuse large B-cell lymphoma, leg type Essential Morphology and phenotype consistent with aggressive B-cell lymphoma Mature B-cell phenotype Diffuse growth with absence of follicular dendritic cell meshworks Skin-confined disease at presentation Desirable Strong BCL2 expression Expression of IgM and MUM1, non-GCB phenotype
High-grade B-cell lymphoma with MYC and BCL2 rearrangements Essential Morphology and phenotype consistent with aggressive B-cell lymphoma Evidence of concurrent MYC and BCL2 rearrangements Desirable GCB Phenotype TdT protein expression status (negative) Determination of MYC fusion partner
Mantle cell lymphoma (CD5+) Essential B-cell immunophenotype with CD5 expression Classic or variant (e.g., blastoid or pleomorphic) morphology CyclinD1 positive or detection of CCND1 rearrangement Desirable SOX11 positive
B-lymphoblastic leukemia/lymphoma (lymphoma-type presentation) Essential Diffuse involvement by a monomorphic population of blasts with a B-cell phenotype (CD19, CD22, cCD79a, and/or PAX5) and markers of immaturity (TdT, CD34, and/or CD10) Desirable Immunophenotype associated with specific recurrent genetic abnormalities Identification of specific recurrent genetic abnormalities
