Primary lymphoproliferative lesions of the mammary gland.

Occasionally, the breast is the site of a localized, primary lymphoma with no evidence of concurrent widespread or preceding extramammary disease at the time of presentation (Stage I) or within 1-6 months thereafter. Cases with concurrent or subsequent ipsilateral axillary node involvement (Stage II) have also been accepted as primary lymphomas by some investigators, and such involvement has been observed in 48.5% of the cases. More commonly, the breast is involved secondarily by widespread lymphoma. Patients with PML range in age from 9 to 90 years, with a median ranging from 55 to 68 years in various reports. Clinical symptomatology varies considerably. Most patients present with a breast mass or complain of pain. About 10% of the patients may have night sweats, fever, and weight loss. Occasionally multiple nodules may be present within the breast. These nodules can cause overlying skin changes similar to those associated with carcinoma and may even involve the nipple. Mammographically, lymphomas form relatively circumscribed masses, focal or diffuse thickening and densities, and discrete nodules with irregular margins; typically, they lack calcification and retraction.