Cytogenetic Evidence for the Origin of Neoplastic Cells in CD5-positive Marginal Zone B-cell Lymphoma

We describe an 87-year-old female patient presenting with a breast lump and axillary lymphadenopathy. Histological examination revealed the lump to be a CD5-positive extranodal marginal zone B-cell lymphoma (MZBCL) of mucosa-associated lymphoid tissue. Subsequent staging revealed disseminated disease including the head and neck region. Only 2 cases of CD5-positive MZBCL have undergone any form of cytogenetic analysis, and we report the first standard karyotype of such a case. This revealed partial trisomy 3,7q deletion and an additional marker chromosome. Notably, cells lacked the t(11;14) found at high frequency in mantle cell lymphoma and trisomy 12 found in B small lymphocytic lymphoma (B-SLL). These results, combined with the clinical, histological, and immunophenotypic picture, suggest a marginal zone origin for the neoplastic lymphocytes, rather than a relationship with mantle cell or small lymphocytic lymphoma.