Extranodal Lymphoma of the Breast.

Extranodal lymphoma represents fewer than 0.5% of all breast malignancies. Secondary involvement of the breast with lymphoma is more common than primary breast lymphoma.

IgG4-related disease of the head and neck.

IgG4-related disease is an uncommon sclerosing and inflammatory mass-forming disease that may affect a single organ or be systemic. The prototypical example of the disease is type 1 autoimmune pancreatitis. After the pancreatobiliary system, the head and neck is the next most common site for involvement by IgG4-related disease.