Hodgkin Lymphoma : Classification
Age Distribution: Classic Hodgkin lymphoma (cHL) shows bimodal age distribution with the first peak between 15 and 35 yrs. and second smaller peak around 70 years of age. The average age at diagnosis is about 32 years. It is uncommon in children, except in developing countries where the incidence in children is higher. There is slight male predominance (M:F = 1.5:1). Male-to-female ratios vary with histologic subtype. Classification: Four subtypes of cHL are currently recognized based on the morphology of neoplastic cells, tissue architecture, and characteristics of the background reactive immune cells - nodular sclerosis, mixed cellularity, lymphocyte-rich, and lymphocyte-depleted. Nodular sclerosis subtype is more frequent in young adults, whereas mixed cellularity is the main subtype in children and older patients. With the current therapeutic regimens, histologic subtyping has become less relevant clinically or prognostically, and a diagnosis of classic Hodgkin lymphoma is sufficient. Histologic subtyping should also not be done in cases of recurrent Hodgkin lymphoma.