RESUMEN
Pathological diagnosis of breast cancer often includes cases of lymph node metastases without lymphatic or lymphovascular invasion by the primary tumor. In this study, to resolve this discrepancy, we designed a sensitive method to detect lymphatic invasion and correlate it with lymph node metastasis. Elastica van Gieson (EVG) staining and D2-40 immunohistochemistry revealed the abundant distribution of lymphatic vessels around blood vessels in the mammary tissue in close proximity to the elastic fibers around the arteries and veins. Based on the histological location of the blood and lymphatic vessels, we hypothesized that, in breast cancer, perivascular invasion is similar to lymphatic invasion and correlates with the presence of lymph node metastasis. Using EVG staining, perivascular invasion was histologically classified into periarterial invasion (periA), perivenous invasion (periV), and periarterial or perivenous invasion (periA/V). We tested our method and compared it to other methods commonly used for identifying lymphatic invasion in 105 patients with invasive breast carcinoma of no special type (IBC-NST) who received minimal preoperative therapy. The correlation between perivascular invasion and lymph node metastasis in these patients was statistically analyzed, including findings related to lymphatic invasion, such as retractile artifacts and perineural invasion. PeriA, periV, and periA/V showed significant correlations with lymph node metastasis. PeriA/V had high sensitivity and negative predictive value. The odds ratio (OR) for periV was significantly high in the univariate analysis, while the ORs for periA/V, retraction artifacts, and perineural invasion were significantly high in both the univariate and multivariate analyses. In particular, periA/V revealed a strong correlation with lymph node metastasis (OR: 61.8). These findings indicate that the IBC-NST periA/V ratio is a sensitive pointer of lymphatic invasion and could be an independent and reliable indicator of lymph node metastasis.