Table 1.

Classification of breast lymphoma according to the number of involved extranodal organs

	Definition
OED	Isolated extranodal organ (i.e. breast) involvement with or without nodal disease, which included distant systemic nodal disease as well as regional nodal disease.
MED	Multiple extranodal organ involvement including one or both breasts regardless of any involvement of lymph nodes

Abbreviations: OED, one exgtranodal disease in the breast; MED, multiple extranodal disease.