BENIGN LYMPH-NODE INCLUSIONS MIMICKING METASTATIC CARCINOMA

Aims-To draw attention to nonneoplastic inclusions in axillary lymph n odes removed from women with primary breast cancer which may be mistak en for metastases. Methods-Five examples of non-malignant inclusions w ere detected in axillary lymph nodes removed fi om women with mammary carcinoma. Immunohistochemical staining for CAM 5.2 and S100 markers, as well as morphological assessment were performed. Results-Three of t he five cases comprised naevus cells and two heterotopic epithelial el ements. One of each was initially mistaken for metastatic carcinoma. N aevus cells in the capsule of axillary nodes are often arranged as lin es of small, round cells and may readily be misinterpreted as metastat ic lobular carcinoma. Heterotopic epithelial elements, in the form of tubules, can easily be mistaken for metastasis from an infiltrating du ctal carcinoma. Conclusions-Awareness of the occasional occurrence of non-neoplastic nodal inclusions will help avoid misdiagnosis. If immun ohistochemical markers for epithelial cells are used to screen lymph n odes for metastasis, such lesions could be detected more frequently. I t is important to combine immunohistochemistry with morphological asse ssment and the use of a panel of antibodies in histological diagnosis.