Background <p>Accurate pathological evaluation and reporting of partial mastectomy specimens are essential for determining appropriate postoperative management in breast-conserving surgery. Although the Japanese Breast Cancer Society (JBCS) Guidelines provide recommendations regarding specimen handling, actual practices at individual institutions have not been fully clarified. This study aimed to assess the current status in Japan and identify aspects for improving the quality and standardization of pathological reporting.</p> Methods <p>A nationwide survey was conducted among 247 institutions certified by the JBCS in Japan, and responses were obtained from 161 institutions. The questionnaire addressed various aspects of specimen handling, including sectioning orientation, definitions of margin positivity, and reporting formats. The responses were analyzed with reference to internationally recognized standards, and the same questionnaire was also distributed to selected international experts to enable supplementary comparison.</p> Results <p>Margin positivity in invasive carcinoma was defined as tumor exposure by 83% of institutions, while 17% also considered close margins positive. 85% of institutions documented the distance to close margins, but this was less frequent than documentation of margin direction (94%) and histologic components (96%). For superficial (skin-side) and muscle-side margins, some institutions reported findings only when positive. Taken together, these inconsistencies raise concerns that clinically important information may not always be captured and communicated.</p> Conclusions <p>Specimen handling practices were generally consistent with national guidelines, but documentation of certain elements, such as the distance to close margins, varied among institutions. Further standardization of pathology reporting, with attention to international standards, is warranted to improve clarity and clinical utility.</p>