Preparation of fine needle aspiration biopsy samples for flow cytometric analysis.

In order to improve the quality of flow cytometric (FCM) DNA histograms, a new preparatory method was tested on samples obtained by fine needle aspiration biopsy (FNAB) of breast tumors. Twenty-four samples were obtained in vivo (group 1), and 20 were obtained from surgically resected specimens (group 2). Tumors from both groups were aspirated twice each. The first sample was injected directly into 70% ethanol, whereas the second sample was pretreated with a mixture of Tween-20 and citric acid solution (Tween-20 CA) before ethanol fixation. The coefficient of variation (CV) of G0-G1 peaks of Tween 20 CA-pretreated samples varied from 1.85 to 5.10 (mean, 3.3) in group 1 and from 1.87 to 3.72 (mean, 2.77) in group 2. The CV of G0-G1 peaks of ethanol-preserved samples ranged from 2.28 to 7.22 (mean, 5.23) in group 1 and from 1.78 to 4.04 (mean, 3.48) in group 2. The CV values of histograms obtained by the new protocol were significantly lower (group 1, P < .05; group 2, P < .01).