Lymph Node Infarction

CONTEXT: The etiology of lymph node infarction may be difficult or impossible to determine by histologic examination. Lymph node infarction is followed by malignant lymphoma in some but not all patients. The role of immunohistochemistry in the evaluation of lymph node infarction is not well defined. Although it is widely believed that necrotic tissue is not suitable for immunohistochemical study, this view may be inaccurate. OBJECTIVE: To determine whether lymphoid antigens are preserved in infarcted lymph nodes and to determine the utility of immunohistochemical staining in the evaluation of lymph node infarction. DESIGN: Retrospective immunohistochemical study of infarcted lymph nodes using archival formalin-fixed, paraffin-embedded tissue. SETTING: Academic medical center. PATIENTS: Eleven adult patients with lymph node infarction retrieved from pathology files. MAIN OUTCOMES MEASURES: Results of immunohistochemistry, diagnosis of lymphoma. RESULTS: Preservation of lymphoid antigens was observed in 4 of 6 cases of lymph node infarction associated with malignant lymphoma, including 3 of 5 cases of diffuse large B-cell lymphoma and 1 case of peripheral T-cell lymphoma. Nonspecific staining was not encountered. In 1 case, in which an infarcted lymph node showed a benign pattern of lymphoid antigen expression, lymphoma has not developed after 5 years. CONCLUSION: Lymphoid antigens are frequently preserved in cases of lymph node infarction, and immunohistochemical study of infarcted lymph nodes may provide clinically useful information.