After studying this chapter you should understand:
The origin of the tumor cell of Hodgkin lymphoma, the Reed-Sternberg cell.
The origin of the reactive infiltrate that surrounds Reed-Sternberg cells.
The pathologic and clinical distinctions between Hodgkin lymphoma and non-Hodgkin lymphoma.
Hodgkin lymphoma bears the name of Thomas Hodgkin, who described the disease in 1832. It affects about 8500 patients each year in the United States and is distinguished from all other forms of lymphoma (the non-Hodgkin lymphomas) by several unique pathologic and biologic features.
The presence of Reed-Sternberg cells or variants and peculiar tumor giant cells within an exuberant tissue response consisting of reactive lymphocytes, granulocytes, macrophages, and plasma cells. Unlike virtually all other forms of cancer, in Hodgkin lymphoma the tumor cells make up a small fraction (often <1%) of the overall tumor mass.
A strong tendency to arise within a single lymph node group and to spread in a predictable, stepwise fashion from one lymph node group to the next. As a result, staging has a greater influence on the treatment of Hodgkin lymphoma than on non-Hodgkin lymphomas.
CLASSIFICATION OF HODGKIN LYMPHOMA
Hodgkin lymphoma is divided into five major pathologic subtypes based on differences in the appearance of the Reed-Sternberg cells and variants as well as the composition of the reactive cellular response:
Nodular sclerosis. This form is most common in young adults and sometimes occurs in adolescents and even children. It is characterized by two pathologic findings: 1) the presence of a particular type of Reed-Sternberg cell variant, the lacunar cell (Fig. 23-1A), and 2) the presence of large bands of collagen that are deposited by reactive fibroblasts. The reactive background consists of a variable mixture of lymphocytes (mainly T cells), granulocytes (particularly eosinophils), macrophages, and plasma cells. The nodular sclerosis subtype is only rarely associated with Epstein-Barr virus (EBV).
Mixed cellularity. This subtype is most common in older males in the United States but also occurs in young adults and children, particularly in parts of the developing world such as Peru. Lymph nodes are diffusely effaced by a polymorphous infiltrate composed of a mixture of inflammatory cells, scattered classic Reed-Sternberg cells (Fig. 23-1C), and relatively frequent mononuclear Reed-Sternberg variants (Fig. 23-1B). About 70% of cases are associated with EBV (Fig. 23-2).
Lymphocyte rich. This is an uncommon subtype in which the predominant cellular response consists of lymphocytes. About 40% of cases are associated with EBV.
Lymphocyte depleted. This is a rare subtype except in human immunodeficiency virus (HIV)-positive patients. Frequent Reed-Sternberg cells are seen in involved tissue sections, whereas the host response to these cells is relatively sparse. It is almost always associated with EBV, particularly in those who are HIV positive.
Nodular lymphocyte predominant. This uncommon subtype (5% of cases) most often arises in young to middle-aged males within axillary or cervical lymph nodes. The tumor cells have nuclei that are lobulated or popcorn kernel–like (Fig. 23-1D); classic Reed-Sternberg cells are rare or absent. For historic reasons, the tumor cells in this subtype are referred to as lymphocytic and histiocytic variants, or L&H cells. L&H cells are typically present within nodular aggregates of B lymphocytes, which represent expanded B-cell follicles. This form of Hodgkin lymphoma is not associated with EBV.