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1598 Part XI: Malignant Lymphoid Diseases Chapter 96: Pathology of Lymphomas 1599

Figure 96–33. Anaplastic large cell lymphoma stained with antibody Figure 96–35. Diagnostic Reed-Sternberg cell in Hodgkin lymphoma.
to CD30.
cells alone is insufficient for a diagnosis of Hodgkin lymphoma, because
abnormalities have been identified in ALK-negative ALCL, involving cells with similar morphology can be seen in a variety of non-Hodgkin
DUSP22 and TP63 genes. 62,63 lymphomas and benign reactive conditions. For a diagnosis of Hodgkin
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Other types of mature T/NK cell lymphomas are uncommon and lymphoma, diagnostic Reed-Sternberg cells must be found in an appro-
include enteropathy-associated T-cell lymphoma (an aggressive T-cell priate background consisting of a variable polymorphous reactive infil-
lymphoma typically arising in the small bowel from a background of trate of inflammatory and accessory cells. 67
celiac disease) and extranodal NK/T-cell lymphoma, nasal type (an Reed-Sternberg cells are derived from B cells in the vast major-
aggressive Epstein-Barr virus [EBV]-associated neoplasm commonly ity of cases of classical Hodgkin lymphoma, as determined by clonal
involving the nasal cavity). A detailed description of these specific lym- rearrangement of IGH genes. However, Reed-Sternberg cells have
68
phoma subtypes is beyond the scope of this chapter and can be found in lost most of their B-lineage antigens, including expression of immu-
the WHO classification. 14 noglobulin. Reed-Sternberg cells express CD30 in almost all cases of
classical Hodgkin lymphoma and express CD15 in the majority (Figs.
67
HODGKIN LYMPHOMA 96–36 and 96–37). They typically are negative for CD45 (leukocyte
common antigen) and positive for B-cell marker CD20 in 20 to 40 per-
Hodgkin lymphoma consists of two distinct clinicopathologic entities: cent of cases, usually of variable intensity in a minority of cells. Classical
classical Hodgkin lymphoma (including four subtypes) and nodular lym- Hodgkin lymphoma is associated with EBV in 20 to 40 percent of cases
69
phocyte predominant Hodgkin lymphoma (Chap. 97). and is thought to play a role in the pathogenesis of these cases. Reed-
Sternberg cells express many cytokines and several members of the
tumor necrosis factor receptor family (e.g., CD40, CD30). The cytok-
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CLASSICAL HODGKIN LYMPHOMA ines are thought to play a role in the recruitment of reactive infiltrate
The neoplastic cell of classical Hodgkin lymphoma is the Reed-Stern- and to contribute to Reed-Sternberg cell proliferation and survival. The
berg cell, first described more than 100 years ago. 64,65 It is a large cell tumor necrosis factor receptor family members can be activated by lig-
with two or more nuclei or nuclear lobes, each of which contains a large ands expressed by the surrounding reactive infiltrate, leading to prolif-
eosinophilic nucleolus (Fig. 96–35). The presence of Reed-Sternberg eration and survival.

Figure 96–34. Anaplastic large cell lymphoma stained with antibody Figure 96–36. Classical Hodgkin lymphoma stained with antibody to
to ALK (anaplastic lymphoma kinase). CD30.

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