Pleural, pericardial, and peritoneal effusion specimens present diagnostic challenges and clinical opportunities for cytology. For the patient, these specimens may be the first diagnosis of malignancy or the first sign of disease recurrence. This review aims to provide useful approaches with which to resolve key difficulties in cytologic diagnosis through the use of ancillary studies, focusing on immunohistochemistry. These approaches are suggested in concert with clinical, radiographic, and morphologic findings. The differentiation of reactive mesothelial cells from malignant mesothelioma and adenocarcinoma is a recurring theme, and Wilms tumor 1 (WT1)/AE1/AE3, claudin 4, and BRCA1-associated protein 1 (BAP1) immunostains are useful new tools in the armamentarium. A targeted workup is suggested for patients with no known primary site or with multiple prior malignancies. Molecular and other biomarker testing can be performed on even modestly cellular fluid specimens and may allow patients to benefit from targeted therapy without the need for additional tissue biopsies. Cancer Cytopathol 2018;000:000-000. © 2018 American Cancer Society.

The nuclear RNA and DNA helicase Sen1 is essential in the yeast Saccharomyces cerevisiae and is required for efficient termination of RNA polymerase II transcription of many short noncoding RNA genes. However, the mechanism of Sen1 function is not understood. We created a plasmid-based genetic system to study yeast Sen1 in vivo. Using this system, we show that (1) the minimal essential region of Sen1 corresponds to the helicase domain and one of two flanking nuclear localization sequences; (2) a previously isolated terminator readthrough mutation in the Sen1 helicase domain, E1597K, is rescued by a second mutation designed to restore a salt bridge within the first RecA domain; and (3) the human ortholog of yeast Sen1, Senataxin, cannot functionally replace Sen1 in yeast. Guided by sequence homology between the conserved helicase domains of Sen1 and Senataxin, we tested the effects of 13 missense mutations that cosegregate with the inherited disorder ataxia with oculomotor apraxia type 2 on Sen1 function. Ten of the disease mutations resulted in transcription readthrough of at least one of three Sen1-dependent termination elements tested. Our genetic system will facilitate the further investigation of structure-function relationships in yeast Sen1 and its orthologs.T RANSCRIPTION termination by eukaryotic RNA polymerase II (Pol II) uses at least two pathways, one that is coupled to cleavage and polyadenylation of the nascent transcript [the poly(A)-dependent pathway] and one that involves the activity of the RNA/DNA helicase Sen1 (the Sen1-dependent pathway) (Kuehner et al. 2011). The Sen1-dependent pathway was first identified in the budding yeast Saccharomyces cerevisiae and is responsible for transcription termination of many short, noncoding RNA genes, including small nuclear (sn) and small nucleolar (sno) RNAs (Winey and Culbertson 1988;Steinmetz and Brow 1996;Rasmussen and Culbertson 1998;Steinmetz et al. 2001). It also restricts the elongation and accumulation of pervasive cryptic unstable transcripts (Arigo et al. 2006b;Thiebaut et al. 2006) and regulates transcription of some protein-coding genes by premature termination, i.e., attenuation (Steinmetz et al. 2001;Arigo et al. 2006a;Steinmetz et al. 2006b;Jenks et al. 2008;Kuehner and Brow 2008). A set of core factors distinguish the Sen1-dependent pathway from the poly(A)-dependent pathway, including Sen1 and the RNA-binding proteins Nrd1 and Nab3 Brow 1996, 1998;Conrad et al. 2000;Steinmetz et al. 2001;Carroll et al. 2007). However, some short messenger RNA (mRNA) genes, such as CYC1, may have hybrid terminators that require factors from both pathways (Steinmetz et al. 2006b).S. cerevisiae Sen1 is a 252-kDa superfamily 1 helicase encoded by the essential SEN1 gene. Its helicase domain is located in the C-terminal half of the protein ( Figure 1A), and the N-terminal 975 amino acids are dispensable for viability (DeMarini et al. 1992). The ortholog of Sen1 in the fission yeast Schizosaccharomyces pombe has ATP-dependent, 59-to-39 DNA and RNA unw...

Circulating tumor cells (CTCs) have long been assumed to be the substrate of cancer metastasis. However, only in recent years have we begun to leverage the potential of CTCs found in minimally invasive peripheral blood specimens to improve care for cancer patients. Currently, CTC enumeration is an accepted prognostic indicator for breast, prostate, and colorectal cancer; however, CTC enumeration remains largely a research tool. More recently, the focus has shifted to CTC characterization and isolation which holds great promise for predictive testing. This review summarizes the relevant clinical, biological, and technical background necessary for pathologists and cytopathologists to appreciate the potential of CTC techniques. A summary of relevant systematic reviews of CTCs for specific cancers is then presented, as well as potential applications to precision medicine. Finally, we suggest future applications of CTC technologies that can be easily incorporated in the pathology laboratory, with the recommendation that pathologists and particularly cytopathologists apply these technologies to small specimens in the era of “doing more with less.”

Stage specific embryonic antigen-1 (SSEA-1), also known as CD15, is a member of cluster of differentiation antigens that have been identified in various normal tissues and in different types of cancers including papillary and medullary thyroid carcinoma. SSEA-1 may be expressed in normal stem cells and cancer stem-like cells. To evaluate the potential diagnostic and prognostic utility of SSEA-1 in thyroid tumors, we analyzed the expression of SSEA-1 in normal and neoplastic thyroid tissues by immunohistochemistry (IHC) using a tissue microarray with 158 different tissue cores. To evaluate the potential utility of SSEA-1 as a surface marker, we also assessed the expression of SSEA-1 in thyroid cell lines by flow cytometric analysis. SSEA-1 immunoreactivity was identified in malignant thyroid follicular epithelial cancers but not in the benign thyroid tissues. Anaplastic thyroid (ATC) (80%) and conventional papillary thyroid carcinoma (PTC) (60.7%) showed significantly higher percentage of cases that were SSEA-1 immunoreactive than follicular variant of papillary thyroid carcinoma (FVPTC) (20.6%) and follicular carcinoma (FCA) (32.1%). Flow cytometric analysis of cultured thyroid cell lines showed that a small subpopulation of ATC and PTC thyroid tumor cells had SSEA-1 immunoreactivity which may represent thyroid cancer stem-like cells. The ATC cells expressed more SSEA-1 immunoreactive cells than the PTC cell lines. Our findings suggest that expression of SSEA-1 immunoreactivity in thyroid neoplasms was associated with more aggressive thyroid carcinomas. SSEA-1 is a marker that detects malignant thyroid neoplasms in formalin fixed-paraffin embedded thyroid tissue sections and may be a useful marker for thyroid cancer stem-like cells.

There has been increasing pressure for systemization in cytopathology. Lack of uniformity in categorization, variation in opinion based regional practice, and technologic advancement have created an environment disposed toward creation of more consistent evidence‐based approaches to diagnostic problems. This review provides an overview of the major standardized terminology systems in cytology, with historical perspectives and commentary on current uses of these systems. These systems now include gynecologic, thyroid, pancreaticobiliary, urinary, salivary gland, and breast cytology. We summarize major classification systems supported by national and international professional organizations, outlining the structure and goals of each system. Specific benefits and potential pitfalls in the implementation of each system are given. Finally, we address potential criticisms of standardized terminology systems and proposed future directions to continue the evolution of standardized terminology to improve clinical practice.