Nodular lymphocyte predominant hodgkin lymphoma and T cell/histiocyte rich large B cell lymphoma--endpoints of a spectrum of one disease?

Abstract

In contrast to the commonly indolent clinical behavior of nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), T cell/histiocyte rich large B cell lymphoma (THRLBCL) is frequently diagnosed in advanced clinical stages and has a poor prognosis. Besides the different clinical presentations of these lymphoma entities, there are variants of NLPHL with considerable histopathologic overlap compared to THRLBCL. Especially THRLBCL-like NLPHL, a diffuse form of NLPHL, often presents a histopathologic pattern similar to THRLBCL, suggesting a close relationship between both lymphoma entities. To corroborate this hypothesis, we performed gene expression profiling of microdissected tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL. In unsupervised analyses, the lymphomas did not cluster according to their entity. Moreover, even in supervised analyses, very few consistently differentially expressed transcripts were found, and for these genes the extent of differential expression was only moderate. Hence, there are no clear and consistent differences in the gene expression of the tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL. Based on the gene expression studies, we identified BAT3/BAG6, HIGD1A, and FAT10/UBD as immunohistochemical markers expressed in the tumor cells of all three lymphomas. Characterization of the tumor microenvironment for infiltrating T cells and histiocytes revealed significant differences in the cellular composition between typical NLPHL and THRLBCL cases. However, THRLBCL-like NLPHL presented a histopathologic pattern more related to THRLBCL than NLPHL. In conclusion, NLPHL and THRLBCL may represent a spectrum of the same disease. The different clinical behavior of these lymphomas may be strongly influenced by differences in the lymphoma microenvironment, possibly related to the immune status of the patient at the timepoint of diagnosis.

Figure 1. Immunoarchitectural patterns of NLPHL, THRLBCL-like NLPHL and THRLBCL, modified after Fan et al..

a.–d. CD20-immunostainings (100x) of NLPHL patterns A and C, THRLBCL-like NLPHL and THRLBCL. e.–h. Schematic forms of immunoarchitectural patterns. Stars: tumor cells, dots: reactive B cells. a./e. Typical NLPHL Fan pattern A; b./f. NLPHL Fan pattern C; c./g. THRLBCL-like NLPHL (Fan pattern E); d./h. THRLBCL.

Figure 2. Unsupervised hierarchical clustering and principal component analysis of gene expression profiles of microdissected tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL, as well as sorted tonsillar GC B cells.

a. Unsupervised hierarchical clustering of the gene expression profiles of the tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL as well as CD77⁺ GC B cells. All probesets with a standard deviation ≥0.9 (479 probesets) were considered. GC B cell samples are indicted by a grey bar. b. Principal component analysis of the gene expression profiles of the tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL. All probesets with a standard deviation ≥1.2 (79 probesets, 40.18% diversity) were considered.

Figure 3. Validation on protein level of genes expressed in both THRLBCL-like NLPHL and THRLBCL identified by gene expression profiling.

a., b. and c.: Strong expression of BAT3/BAG6 in the tumor cells of typical NLPHL (pattern A), THRLBCL-like NLPHL and THRLBCL, 200x. Inset: Positive tumor cells in 400x. d., e. and f.: Expression of HIGD1A in the tumor cells of typical NLPHL (pattern A), THRLBCL-like NLPHL and THRLBCL, 200x. Inset: Positive tumor cells in 400x. g., h. and i.: Expression of UBD/FAT10 in the tumor cells of typical NLPHL (pattern A), THRLBCL-like NLPHL and THRLBCL, 200x. Inset: Positive tumor cells in 400x. j., k. and l.: Expression of CXCL13 in rosetting T cells of typical NLPHL (pattern A) and in the tumor cells of THRLBCL-like NLPHL and THRLBCL, 200x. Insets in 400x. m., n. and o.: Expression of ICOS in the tumor cells of typical NLPHL (pattern A), THRLBCL-like NLPHL and THRLBCL, 200x. Inset: Positive tumor cells in 400x.

Figure 4. Quantification of the microenvironment in typical NLPHL (patterns A and C), THRLBCL-like NLPHL (pattern E) as well as THRLBCL.

a. Numbers of CD4⁺ T cells/mm² in typical NLPHL (pattern A: n = 14 and pattern C: n = 13), THRLBCL-like NLPHL (n = 14) and THRLBCL (n = 25). (*p<0.05, **p<0.01, unpaired t-test). b. Numbers of CD8⁺ T cells/mm² in typical NLPHL (pattern A: n = 14, pattern C: n = 15) and THRLBCL-like NLPHL (n = 12) as well as THRLBCL (n = 22). c. Numbers of CD163⁺ macrophages/mm² in NLPHL (pattern A and C as well as THRLBCL-like NLPHL: n = 14, each) and THRLBCL (n = 25), (***p<0.001, Mann-Whitney-test).