Which of the following features cannot be used to differentiate between Hodgkin's and Non Hodgkin's Lymphoma ?
Hodgkin lymphoma, like NHL, usually manifests as painless lymphadenopathy.  Although a definitive distinction from NHL can be made only by examination of a tissue biopsy,  several clinical features favor the diagnosis of Hodgkin lymphoma. After the diagnosis is established, staging is used to guide therapy and determine prognosis.
Extranodal involvement
Spread contiguity
Painless lymphadenopathy
Localisation to a particular group of lymph nodes