Hodgkin Disease (HD) is a malignant tumor affecting 5.5% of all pediatric cancers. It is characterized by pleomorphic lymphocytic and histiocytic infiltrate with multinucleated Reed-Sternberg cells (RS). The RS cells are clones of B origin which are located in the lymphoid germinal centres. It consists only 2% of all HD affected tissues, whereas the remaining cells include lymphocytes, plasma cells, neutrophils, eosinophils, and histiocytes. HD is histologically divided into five types. Four of these types are referred to as classic Hodgkin disease which includes: nodular sclerosis, mixed-cellularity, lymphocyte-depleted, and lymphocyte-rich. The fifth type (non-classical) is nodular lymphocyte predominant Hodgkin disease. About two thirds of pediatric patients are present with the nodular sclerosis type at diagnosis. The primary nodal site of HD is situated above the diaphragm in two third of patients. The usual clinical presentation consists of painless cervical or supraclavicular adenopathy. Splenomegaly and hepatomegaly often indicate advanced disease. The systemic symptoms of HD are typical of B symptoms, including fever, weight loss of 10%, and night sweats. These symtoms are expressed due to the secretion of at least twelve cytokines, including interleukin-1 (IL-1), IL-6 and tumr necrosis factor from the RS cells. In addition, the malignant RS cells are known to constitutively express high levels of activated nuclear factor kappa B (NFKB), which plays an important role in their survival. Also, the RS cells consistently express the CD30 and CD15 antigens, which are serving as malignant markers in the classical types. However, the RS cells are either infrequent or absent in nodular lymphocyte predominant type.
The etiology of HD is unknown. However, Epstein-Barr virus (EBV) has been reported to involve in the etiology of HD. In addition, other studies suggest other environmental factors such as exposure to pesticides or tonillectomy may also play a role.
Unlike most malignant tumors, HD is curable and the overall survival is more than 90% due to the pregressive advances in new diagnostic methods (CT scan, MR and Gallium scan) and treatment. Currently, all children receive combind chemotherapy with low dose irradiation (1500-2000 cGy) solely in the initially involved area instead of high doess (3600-4000 cGy).