Flow cytometric analysis of DNA ploidy in lymphomas of the thyroid.

Four cases of primary non-Hodgkin's lymphoma (NHL) of the thyroid were studied using flow cytometric (FCM) DNA analysis of propidium iodide-stained nuclei retrieved from formalin-fixed, paraffin-embedded tissue. Two of the four cases were aneuploid and two were euploid. In the two euploid cases, both patients are alive and without evidence of recurrent disease after an average of 4 years follow-up. Of the two aneuploid cases, one patient is alive and free of recurrent disease after 1 year. In the other aneuploid case, the patient died of disseminated disease 8 months after presentation despite having a low-grade (follicular, predominantly small cleaved cell type) and low-stage (tumor confined to thyroid at presentation) lymphoma. These data suggest that the DNA ploidy of primary NHL of the thyroid can be determined using fixed, paraffin-embedded tissue. Our results also suggest that a large study to assess the prognostic value of this technique is warranted.