Mitsuhiko Yasuda

Primary breast diffuse large B-cell lymphoma shows a non-germinal center B-cell phenotype

Primary breast diffuse large B-cell lymphoma has a poor prognosis relative to other extranodal diffuse large B-cell lymphoma. Recently, diffuse large B-cell lymphoma has been subclassified as germinal center B-cell-like and nongerminal center B-cell types using tissue microarrays. The 5-year overall survival rate of the germinal center B-cell group is better than that of the nongerminal center B-cell group. To elucidate the reason for which primary breast diffuse large B-cell lymphoma has a poor clinical outcome, we investigated 15 patients with primary breast diffuse large B-cell lymphoma (stage IE; 13 cases, stage IIE; two cases) by immunohistochemistry using various markers including CD10, Bcl-6, MUM1 and MIB-1 and by molecular analysis of the immunoglobulin heavy chain gene variable region. Immunohistochemistry showed 0/15 (positive cases/examined cases) for CD10, 5/15 for Bcl-6, 15/15 for MUM1, 10/15 for Bcl-2, 2/15 for CD5 and 4/15 for CD40. The expression pattern of CD10(−) MUM1(+) in primary breast diffuse large B-cell lymphoma corresponded to the nongerminal center B-cell group. Moreover, the MIB-1 index was distributed from 60 to 95% with a mean of 79%, indicating a high proliferation of the lymphoma cells. The immunoglobulin heavy chain gene variable region of primary breast diffuse large B-cell lymphoma had a mutation frequency of 1–10% (seven cases) and 0–1 additional mutations in ongoing mutation analysis (five cases). Primary breast diffuse large B-cell lymphoma had characteristics of the nongerminal center B-cell group. In conclusion, primary breast diffuse large B-cell lymphoma has a nongerminal center B-cell phenotype and has a high MIB-1 index. These features might therefore be associated with poor prognosis.

Computer‐assisted complete three‐dimensional reconstruction of the mammary ductal/lobular systems

The intraductal spread of breast carcinoma can occur along the mammary ductal/lobular systems (MDLS) with no invasion of tissues. Because ductal anastomoses in the MDLS are considered to be a possible risk factor for extensive intraductal spread of breast carcinoma, the architecture of the MDLS has important therapeutic implications for patients treated with breast‐conserving surgery.

IgG4-related disease of the breast: a systemic disease whose mammary manifestations mimic breast cancer

IgG4-related disease is a newly identified disease entity that has begun to attract attention, and international consensus diagnostic criteria for the condition have recently been proposed. The characteristic features of IgG4-related disease are lymphoplasmacytic infiltration involving a high proportion of IgG4-positive cells, fibrosis exhibiting a storiform pattern, and obliterative phlebitis. It can affect various organs, including the breast (in rare cases). IgG4-related disease has previously been referred to as inflammatory myofibroblastic tumor, plasma cell granuloma, or pseudolymphoma. We have experienced a case of IgG-related disease of the breast. Clinically and cytologically, the lesion was somewhat similar to a malignant tumor. An immunohistochemical examination of a core needle biopsy sample resulted in a correct diagnosis. In addition, a review of the patient’s clinical history revealed that the disease had affected areas other than the breast. Clinicians should be aware that breast lesions can be a focal manifestation of systemic disease, and overdiagnosis should be avoided by performing appropriate pathological analysis.

Pathological aspects of the intraductal spread of breast cancer

The intraductal spread of breast cancer is a major cause of local recurrence following breast-conserving therapy. To properly understand this pathology, three-dimensional (3D) cancer localization within the mammary ductal–lobular system (MDLS) is necessary. To this end we generated computer-assisted 3D reconstructions of all MDLSs using 2-mm-thick serial sections of surgically resected specimens. We then analyzed the characteristics of intraductal spread of breast cancer. In our study of quadrantectomy specimens from patients with primary invasive breast carcinoma, the intraductal spread of breast cancer was found to be continuous from the invasive tumor and spreading along the mammary glandular tree. The pattern is categorized into three types: the central type, the peripheral type, and the extensive type. The central type was found to be most common. A 3D analysis of total mastectomy specimen from a patient with primary non-invasive breast carcinoma revealed regional intraductal spread extending within and filling a single MDLS. The analysis also revealed the presence of ductal anastomoses connecting adjacent MDLSs. These ductal anastomoses were found to be an anatomical risk factor for extensive intraductal spread of breast cancer across multiple MDLSs. To minimize residual non-invasive components of breast carcinoma in the conserved breast, which is strongly associated with the outcome of local control of breast-conserving therapy, it is necessary to determine the optimum surgical margins in a flexible, patient-specific manner. This determination should be based on anatomical characteristics of the MDLS, such as those identified in the present study.