Clinical implications and value of immunohistochemical staining in the evaluation of lymph node infarction after fine-needle aspiration

We report on a series of 3 patients who underwent fine-needle aspiration (FNA) for clinically apparent lymphadenopathy. In all 3 cases, a diagnosis of malignancy was rendered based on cytologic findings (two metastatic squamous-cell carcinomas and one melanoma). However, initial follow-up surgical pathology reported only "extensive coagulative necrosis, no viable tumor seen." Subsequent immunohistochemical stains (cytokeratins (AE1/AE3), HMB45, S100, and Melan A) demonstrated the presence of metastatic tumor in the area of infarction in each case, thus establishing the presence of metastatic tumor and correct interpretation of the initial FNA. We conclude, based on our own experience and a few previously reported cases, that total infarction of the lymph nodes following FNA can occur, and immunohistochemistry can be helpful in clinical management.