Causes of Hodgkin Lymphoma
Scientists do not know what specifically causes Hodgkin lymphoma. There are some known risk factors, but the presence of a risk factor does not in any way ensure that HL will develop, nor is a risk factor necessarily the cause when HL does develop.

Such risk factors include the virus that causes mono, or mononucleosis, which is called the Epstein-Bar virus. Family history is also a risk factor, but it’s not known how or why; that is, there may be shared genes that make family members more susceptible to HL, or perhaps people in the same family had similar childhood diseases that put them at risk for HL. Having a weakened immune system also increases the risk of HL. Such impaired immunity may come from HIV/AIDS, various other illnesses, or from medications used to suppress the immune response.

Who Gets Hodgkin Lymphoma?
Hodgkin lymphoma is less common than NHL overall, accounting for only about 10 percent of all lymphoma cases. It can occur in both children and adults, and there are two peak age groups:

Adolescents and young adults ages 15 to 40 years
Older adults over the age of 55

So, even though HL is relatively rare, if it may seem as though people in their 20s get diagnosed more often, and that’s probably due to the first peak age group.