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Background and aim: Gallstones are known to produce diverse histopathological changes in

Context.-Cell block preparation methods vary substantially across institutions and are frequently suboptimal. The growing importance of biomarker testing in the era of targeted therapies makes optimization of cell block preparation critically important.Objective.-To develop an improved cell block preparation method.Design.-Ex vivo fine-needle aspirates and scrapes from surgically resected tumors were used to develop an improved HistoGel (Thermo Fisher Scientific, Waltham, Massachusetts)-based cell block preparation method. Cellularity yield with the new versus the standard method was assessed in ex vivo split samples and in consecutive clinical fine-needle aspirates processed before (n ¼ 100) and after (n ¼ 100) the new method was implemented in our laboratory. Sufficiency of cell block material for potential molecular studies was estimated by manual cell quantitation.Results.-The key modification in the new method was pretreatment of the pelleted cells with 95% ethanol before the addition of HistoGel (HistoGel þ ethanol method). In addition, we optimized the melting conditions of HistoGel and added a dark, inorganic marker to the cell pellets to highlight the desired level of sectioning during microtomy. Cell blocks from ex vivo split samples showed that the HistoGel þ ethanol method yielded, on average, an 8.3-fold (range, 1-20) greater cellularity compared with the standard HistoGel-only method. After the switch from the standard HistoGel method to the modified method in our clinical practice, sufficiency of positive fine-needle aspirates for some molecular studies increased from 72% to 97% (P ¼ .002).Conclusions.-We describe a simple and readily adoptable modification of the HistoGel method, which results in substantial improvement in cell capture in cell blocks, leading to a significant increase in sufficiency for potential molecular and other ancillary studies.

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BACKGROUND: Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) immunohistochemistry (IHC) guide the clinical management of breast cancer metastases. Decalcification of bone core needle biopsies (CNBs) can affect IHC. In the current study, the authors sought to define whether fine-needle aspiration (FNA) would be a better alternative to CNB for reliable IHC. METHODS: Patients with breast cancer metastases to bone that were sampled by both CNB and FNA were selected. ER, PR, and HER2 were performed in FNA cell blocks (FNA-CBs) and concurrent decalcified CNBs. Discrepancies were classified as minor when there was a difference of up to 30% nuclear staining in IHC for ER and PR between paired samples and as major when a clinically relevant change was observed (ie, positive vs negative). Quantitative reverse transcriptase-polymerase chain reaction of ESR1 messenger RNA levels was performed on FNA/ CNB pairs with discrepancies for ER IHC. IHC status of the primary breast carcinoma was recorded. RESULTS: Concordance rates for ER, PR, and HER2 were 89%, 67%, and 93%, respectively, between FNA-CB and CNB pairs from 27 patients. Major discrepancies were noted in approximately 11% of FNA/CNB pairs for ER IHC and in 33% of FNA/CNB pairs for PR. ESR1 messenger RNA levels of FNA/CNB matched samples were similar and did not explain the differences in ER IHC expression in the majority of cases. Two of 27 FNA/CNB pairs had different results for HER2 IHC that changed from negative on CNB to equivocal (2+) on FNA-CB. Both cases had prior HER2 amplification by fluorescence in situ hybridization. CONCLUSIONS:FNA-CB and CNB appear to constitute acceptable methods for the assessment of ER, PR, and HER2 for clinical decision making. Cancer Cytopathol 2020;128:133-145. Edelweiss performed the immunohistochemical staining review and the protein quantification. Salvatore Piscuoglio performed the quantitative real-time polymerase chain reaction.