Table 1.

Ann Arbor staging classification of thoracic lymphoma

Stage	Area of involvement
I	A single lymph node region or a single localised involvement of an extralymphatic site
II	Two or more lymph node regions on the same side of the diaphragm
III	Lymph node regions on both sides of the diaphragm
IV	Diffuse involvement of one or more extranodal organs with or without lymph node involvement
Additional qualifiers
A	Absence of systemic symptoms
B	Presence of systemic symptoms
S	Involvement of spleen
E	Localised extralymphatic site involvement
H	Involvement of liver
M	Diffuse involvement of bone marrow