Biology and Diagnosis of Hodgkin's Lymphoma
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Hodgkin's lymphoma Biology and diagnosis of Hodgkin’s lymphoma S. Hartmann ABSTRACT M-L. Hansmann Modern diagnostic approaches now allow the establishment of a firm diagnosis of Hodgkin’s lym- phoma (HL) including the different subtypes. Entities to be considered in the differential diagnosis Senckenberg Institute of Pathology, include T-cell lymphomas (follicular variant and angioimmunoblastic T cell lymphoma), T-cell/histio- University of Frankfurt, Frankfurt, cyte rich B-cell lymphoma and progressively transformed germinal centers. Molecular techniques such Germany as single cell investigations, gene expression and sequencing provide new insights into the biology and development of HL. In recent years, it has become more and more evident that not only T cells, but Correspondence: several other cell types, especially macrophages are key players in HL biology. Macrophages seem to Sylvia Hartmann be of prognostic relevance and show different morphologies depending on the immunological status E-mail:[email protected] of the patients (e.g. HIV status). furt.de Martin-Leo Hansmann Learning goals E-mail: [email protected] furt.de At the completion of this activity, participants should know that: - new technologies allowing a precise knowledge of molecular mechanisms in HRS cells give a better understanding of the disease and diagnostic delineation; Hematology Education: - analysis of the microenvironment can give hints as to the immune status of the patient as well as the education program for the to the predictive value of clinical behavior. annual congress of the European Hematology Association 2013;7:187-192 Hodgkin’s lymphoma morphology Hodgkin’s lymphoma subtypes The infiltrate in Hodgkin’s lymphoma (HL) is Hodgkin’s lymphoma is divided into four composed of only few, mostly scattered tumor classical subtypes (90%-95%) and the nodular cells and an abundant reactive background. The lymphocyte predominant HL (approx. 5%). tumor cells in classic HL, the Hodgkin- and Reed- Nodular sclerosis (NSCHL) Sternberg (HRS) cells, can show single or several nuclei and usually show prominent eosinophilic Nodular sclerosis (NSCHL) is the most fre- nucleoli. Immunohistochemically, HRS cells quent subtype in the Western countries and strongly express CD30 (Figure 1), MUM1 and often presents in the mediastinum. The histo- weakly PAX5. They show variable expression of logical picture is characterized by sclerotic markers usually found in other cell lineages bands forming macronodular compartments in including CD15,1 fascin,2 NOTCH1,3 GATA34,5 the lymph node or involved tissue. In these and occasionally Granzyme B.6 HRS cells can compartments a mixed infiltrate containing variably be Epstein-Barr virus (EBV)-infected. B- HRS cells and usually abundant amounts of cell markers such as CD20, CD79a and CD19 are reactive T cells, eosinophils and some epithe- usually not expressed or strongly down-regulated. lioid cells and macrophages can be found. A Weak, heterogeneous expression of CD20 in some high content of eosinophils was found to be a of the HRS cells can sometimes be observed negative prognostic predictor.14 HRS cells in (Figure 1). HRS cells are frequently arranged nodular sclerosis often show a cytoplasmic around remnants of B-cell follicles or are found in retraction artifact when the tissue is formalin the interfollicular areas. The reactive microenvi- fixed and paraffin embedded; therefore, these ronment includes mainly CD4-positive (CD4+) T cells are also called lacunar cells. In nodular cells, epithelioid cells and eosinophils. T cells iso- sclerosis, HRS cells are more often EBV-neg- lated from primary HL tissue are anergic to stim- ative, but this is largely dependent on geo- ulation with mitogen and contain enriched popu- graphical location. A subset of cases shows a lations of T-regulatory 1 and CD4+CD25+ regula- syncytial growth pattern of HRS cells, usually tory T cells.7 Reactive B-cell compartments are around residual regressive follicles. usually only partly preserved. Necrosis can be Mixed cellularity found at a variable frequency. Recently, a high content of macrophages in the tissue has been In mixed cellularity (MCCHL) subtype, the found to be associated with an adverse clinical neoplastic infiltrate is usually found in the behavior.8-11 However, other studies could not con- interfollicular areas. Germinal centers can be firm this finding.12,13 preserved when there is early involvement of Hematology Education: the education program for the annual congress of the European Hematology Association | 2013; 7(1) | 187 | 18th Congress of the European Hematology Association Lymphocyte rich subtype lymph nodes. The neoplastic infiltrate expands from the interfollicular areas and destroys the B-cell areas. The The lymphocyte rich subtype (LRCHL) is another rare reactive microenvironment usually consists of high num- variant of HL. It occurs relatively frequently in the Waldeyer´s ring. Patients are most often diagnosed in bers of T cells, eosinophils and epithelioid cells. Other 16 cases show high amounts of macrophages. The HRS cells stage I. In this particular subtype, HRS cells are located are more often EBV-infected. The mixed cellularity type is in the B-cell nodules or in enlarged mantle zones sur- most frequently found either in young children or elderly rounding reactive germinal centers, which may be pre- and immunocompromised individuals. served. Eosinophils can occasionally be observed. The content of macrophages is relatively low in this subtype. Lymphocyte depleted subtype HRS cells can be positive for EBV. Lymphocyte depleted subtype (LDCHL) is a very rare Nodular lymphocyte predominant Hodgkin’s lymphoma subtype. Like mixed cellularity subtype it predominantly Nodular lymphocyte predominant Hodgkin’s lymphoma occurs in immunocompromised patients. The HRS cells (NLPHL) is the only non-classic HL subtype and it differs are often EBV-infected. Some of the cases previously from classical HL in terms of the immunophenotype of diagnosed as lymphocyte depleted subtype may nowadays tumor cells, molecular findings and clinical behavior. The be better placed in other categories like nodular sclerosis tumor cells in NLPHL, the lymphocyte predominant cells or with a high tumor cells content or gray zone lymphoma LP cells, have a preserved B-cell phenotype, although it can between Hodgkin’s lymphoma and diffuse large B-cell be partially down-regulated (Figure 2).17,18 Like in LRCHL, lymphoma.15 the LP cells show prominent rosetting of follicular T-helper cells (PD-1+) and, therefore, keep their germinal center derived microenvironment in contrast to the other classic HL subtypes.19-21 On clinical grounds, patients with NLPHL often show slowly growing, massively enlarged lymph nodes. Axillary lymph nodes are frequently involved. Middle-aged male patients are often affected.22 Like LRCHL, patients are often diagnosed in stage I.16 Whereas the overall survival of patients is excellent, relapses are more common than in LRCHL.23-25 Transformation into dif- fuse large B-cell lymphoma occurs in up to 30% in 20 years.26,27 Variants of NLPHL with a diffuse growth pattern are associated with a higher relapse risk.28,29 Figure 1. Classic Hodgkin’s lymphoma. (A) Typical multinu- clear Reed-Sternberg cells with a background of T cells, epithelioid cells and eosinophils in a nodular sclerosing HL (HE, 200x). (B) HRS cells are strongly positive for CD30 Figure 2. Nodular lymphocyte predominant Hodgkin’s lym- (CD30-immunostaining, 200x). (C) Some HRS cells can phoma. (A) LP cells (arrows) show popcorn-like nuclei. weakly express CD20 (arrow). Interestingly, the staining They are surrounded by stimulated T lymphocytes with intensity is much weaker than in the reactive small B cells slightly enlarged nuclei and open chromatin (HE, 200x). (right, CD20-immunostaining, 200x). (D) HRS cells in a (B) CD20-positive LP cells (arrows) are found in a nodule nodular sclerosing HL strongly express the glucose trans- of CD20-positive small B cells (CD20-immunostaining, porter GLUT1 (GLUT1-immunostaining, 200x). (E) HRS cells 100x). (C) LP cells strongly express J-chain (J-chain show rosetting by T cells in a mixed cellularity HL (HIV-neg- immunostaining, 200x). (D) LP cells (arrow) show a slight- ative, CD3-immunostaining, 200x). (F) HIV-associated ly less intense PAX5-expression than the small surround- mixed cellularity HL with a high amount of macrophages, ing B cells, indicating a partially down-regulated B cell rosetting around an HRS cell (arrow, CD163-immunostain- phenotype (PAX5-immunostaining 200x). ing, 200x). | 188 | Hematology Education: the education program for the annual congress of the European Hematology Association | 2013; 7(1) Stockholm, Sweden, June 13-16, 2013 k 37 Single cell polymerase chain reaction of the NF- B inhibitor TNFAIP3/A20. In different cases, mutations of other NF-kB inhibiting factors like IkBα, IkBe, CYLD and TRAF3 were found.39-41 Loci covering Since HRS cells have usually lost their B-cell REL as well as other important NF-kB factors frequently immunophenotype and express various markers of other show genomic gains in HRS cells.42-45 Although NF-kB 17 cell lineages, the nature ofet HL al. remained unclear for many activity has been observed in the LP cells of NLPHL , years. In 1994, Küppers 30 could show for the first mutations of TNFAIP3/A20 and IkBα were only rarely time in 3 cases of classic HL and one case of NLPHL that found.46 Similar findings of genomic aberrations and HRS and LP cells are