Endocervicosis involving axillary lymph nodes: first case report.

The occurence of Mullerian epithelial inclusions, especially endosalpingiosis, in pelvic and other subdiaphragmatic lymph nodes is well known. In contrast, Mullerian inclusions involving lymph nodes above the diaphragm is uncommon, although occasional cases of endosalpingiosis have been reported. We report a case of benign Mullerian inclusions of mucinous endocervical type (endocervicosis) coexistent with metastatic breast-infiltrating ductal carcinoma in 2 axillary lymph nodes. The inclusions exhibited diffuse positive staining with CK7, PAX8, CA125, and estrogen receptor and were WT1 negative. To our knowledge, this is the first report of endocervicosis involving supradiaphragmatic lymph nodes. Close morphologic examination and immunohistochemistry assists in distinguishing Mullerian inclusions from metastatic adenocarcinoma.