Molecular characteristics of primary marginal zone B-cell lymphoma of the breasts

Marginal wne lymphoma (MCL) accounts for 7-8% of all lymphoid neoplasms. The World Health Organization (WHO) classification divides them into nodal, extranodal and splenic. Extranodal MZL (EMZL) most often arises in the stomach, lungs, eye adnexa, salivary glands, and thyroid gland. In individual organs, the pathogenesis of EMZL is associated with chronic antigenic stimulation by external factors (e.g. in the stomach with Helicobacter pylori (HP), Borrelia burgdorferi in the skin) or with autoimmune stimulation (e.g. in Hashimoto's thyroiditis or Sjogren's syndrome). Pathogenesis is associated with changes in the number and structure of cbromosomes. In approximately 20-30% of EMZL, trisomies of chromosomes 3, 12 and 18 are present. E.g. t(11,18)(q21;q21), which causes a fusion of the BIRC3 and MALTt genes, is present in about 45% of pulmonary EMZL and 23% of gastric EMZL. It is characteristic of EMZL, as it does not occur in other types of MZL. Regarding the mutational profile, several studies on different types of MZL, including EMZL, bave been published in the last few years. For example in cutaneous EMZL, the most common mutations are TNFAIP3, NOTCH2 and TLBXRl, in thyroid EMZL TET2, and in salivary glands TBLlXR.1 and KMT2D. Given the fact that EMZL is dependent on antigenic stimulation, their regression may occur by removing of the antigen stimula ti on cause ( eg, by antibiotic theraov or administration of immunomodulatory drugs).