Breast lymphoma accounts for less than 1% of all non-Hodgkin's lymphomas (N
HLs) and approximately 0.1% of all breast neoplasms. Most breast lymphomas
are classified as diffuse large B cell or mucosa associated lymphoid tissue
(MALT) lymphomas. The case of a 53 year old woman presenting with a breast
mass and found to have mantle cell lymphoma is described. Core biopsy of t
he breast lesion showed a B cell NHL, probably of large cell type and of hi
gh grade. Morphological and immunophenotypic analysis of peripheral blood a
nd bone marrow samples suggested a mantle cell lymphoma (MCL). This was con
firmed by the detection of a t(11; 14) in the bone marrow aspirate and brea
st tissue by polymerase chain reaction analysis. There have been no previou
s reports of an MCL presenting as a breast lump. Because a diagnosis of MCL
has prognostic and therapeutic implications, this case highlights the need
for an awareness of MCL presenting in this way, and the requirement for sp
ecialised investigations in its detection.