• Portion of a lymph node, with a nest of metastatic breast tumor.

• Note that the histology of the tumor resembles an infiltrating carcinoma of breast.

• Note as well that the tumor is close to the capsule of the lymph node.

• This is a common early site for implantation of metastatic tumors, since they enter the lymph node through afferent lymphatics which empty into the marginal sinus just below the capsule.

•Secondary to malignancies elsewhere, almost always carcinoma, or systemic involvement by lymphoma.

•Rare event for sarcoma.

•Tumors invade lymphatics and spread to the local draining lymph node.

•Here, colonization occurs first underneath the capsule in the marginal sinus.

•Subsequently, the entire lymph node may be involved.

•Common.

•The presence of metastatic deposits in draining lymph nodes generally worsens the prognosis.

•In some malignancies, particularly those of internal viscera, lymph node metastases may be the first indication of a tumor.
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•Grossly, the lymph node may be of normal size or significantly enlarged.

•Depending upon the rate of growth of the tumor, there may be necrosis, cystic change or hemorrhage.

•In extreme cases, cross section may reveal a completely or partially necrotic node, with the center appearing as a white pus-like material.

•Microscopically, the tumor may be seen initially as small deposits of tumor resembling the primary tumor in the marginal sinus.

•Subsequently, deposits may be seen in the medullary region of the lymph node.

•In extreme cases, the entire lymph node may be replaced by tumor, leaving behind very little normal lymphoid tissue.

•Significant areas of necrosis, hemorrhage and liquefaction degeneration may be seen.

• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 297.

• Current literature from PubMed at National Library of Medicine