Breast MALT Lymphoma: A Clinical, Histomorphologic, and Immunophenotypic Evaluation

Area of Science:

• Oncology
• Pathology
• Immunology

Background:

• Primary breast extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a rare entity.
• The developmental link between mammary glands and skin suggests potential overlap with primary cutaneous marginal zone lymphoma.
• Limited research exists on the distinct characteristics of primary breast MALT lymphoma.

Purpose of the Study:

• To analyze and compare the clinical and pathological features of primary and secondary breast MALT lymphomas.
• To investigate potential overlapping features between breast MALT lymphoma and primary cutaneous marginal zone lymphoma.
• To identify distinguishing characteristics of primary breast MALT lymphoma.

Main Methods:

• Retrospective analysis of 5 primary and 6 secondary breast MALT lymphomas over 20 years.
• Comparison of clinical presentations, including age at diagnosis and lymphadenopathy.
• Histopathological analysis, including immunohistochemistry for IgG, IgG4, and CD30 expression.

Main Results:

• Both primary and secondary breast MALT lymphomas typically presented as unilateral breast lesions without axillary lymphadenopathy.
• Primary breast MALT lymphomas occurred in older patients (median 77 years) compared to secondary cases (median 60 years).
• Thyroid abnormalities were common in both groups; features of primary cutaneous marginal zone lymphoma were absent in primary breast MALT lymphomas but present in one secondary case with cutaneous origin.

Conclusions:

• Primary breast MALT lymphoma lacks the distinctive features of primary cutaneous marginal zone lymphoma.
• Elevated IgG and IgG4 positive cells with a high IgG/IgG4 ratio in breast MALT lymphoma may suggest a cutaneous origin.
• CD30 overexpression might be associated with marginal zone lymphomas of cutaneous origin, warranting further investigation.