Rabbit monoclonal E-cadherin antibody: A cost-effective alternative to mouse monoclonal antibody in distinguishing ductal carcinoma in situ from lobular carcinoma in situ.

Rabbit monoclonal antibody (RabMAb) demonstrates higher sensitivity without sacrificing specificity than mouse monoclonal antibody (MMAb). MMAb against E-cadherin stain is heavily utilized in distinguishing ductal carcinoma in situ (DCIS) from lobular carcinoma in situ (LCIS). We aimed to compare the E-cadherin stain using RabMAb vs MMAb in distinguishing DCIS from LCIS. One hundred and seventeen in situ breast carcinomas (55 DCIS, 58 LCIS, and 4 DCIS and LCIS) were studied. Sections from a representative block of each were stained with RabMAb [EP700Y] and MMAb [36B5]. Scanned images of stained slides were compared in tandem. All DCIS cases (59/59) showed comparable staining by RabMAb and MMAb. Comparable staining was also observed in all but one case of LCIS (61/62; 98%). One case of pleomorphic LCIS showed mostly complete, weak to moderately intense membranous staining with RabMAb and fragmented, weak membranous staining with MMAb. Consistently better staining quality was observed in slides stained by RabMAb vs MMAb. RabMAb and MMAb against E-cadherin were diagnostically equivalent with the exception of one case where RabMAb may have led to diagnostic misinterpretation. However, the not insignificant cost savings and easier interpretation using RabMAb may justify the risk of misinterpretation of increased staining in rare cases, largely avertable with proper training.

Mammary Epithelial-Myoepithelial Carcinoma: Report of a Case With HRAS and PIK3CA Mutations by Next-Generation Sequencing.

We present the case of a 73-year-old woman with an epithelial-myoepithelial carcinoma of the left breast (ie, malignant adenomyoepithelioma). In both the initial needle core biopsy and in the subsequently performed lumpectomy, the tumor consisted of nests of neoplastic epithelium and myoepithelium with cytologic atypia, increased mitoses, and infiltrative growth into the surrounding tissue. Mutational analysis showed oncogenic driver mutations in HRAS and PIK3CA. In this article, we describe an epithelial-myoepithelial carcinoma of the breast with focal metaplastic differentiation, an extremely rare entity, and report the results of targeted next-generation sequencing. Our patient has not shown any evidence of recurrent or metastatic disease at 29 months follow-up.

Cytological diagnosis of papillary thyroid carcinoma with tall cells on ThinPrep liquid-based cytology.

BACKGROUND: The tall cell variant of papillary thyroid carcinoma (PTC-TC) has been associated with aggressive features including extrathyroidal extension, higher rate of lymph node and distant metastases, and higher recurrence rate. We aimed to evaluate the cytomorphologic features of PTC-TC on ThinPrep (TP) along with its diagnostic efficacy to detect PTC-TC. METHODS: Preoperative cytology samples from 30 cases of histologically-proven PTC-TC and 30 classical PTC controls were selected for this study. TP preparations were evaluated for varying architectural and cytomorphologic features. RESULTS: Tall cells were present in the majority of PTC-TC cases and were located at the periphery of cell clusters and as single cells. Cytoplasmic cuff along the periphery of cell clusters and soap-bubble pseudoinclusions were very specific features of PTC-TC, when present. PTC-TC cases were more likely to show abundant oncocytic cytoplasm and distinct cell borders. Cytoplasmic tails were more likely to be present and more numerous in PTC-TC. The presence of nuclear grooves, papillary architecture, and giant cells were not reliable distinguishing features of PTC-TC vs controls. CONCLUSION: Our results indicate that tall cell cytomorphologic and architectural features in PTC are identifiable on TP.

Accuracy of next-generation sequencing for the identification of clinically relevant variants in cytology smears in lung adenocarcinoma.

BACKGROUND: Minimally invasive diagnostic procedures such as needle-core biopsy and fine-needle aspiration provide adequate material for molecular analyses. Advances in precision oncology are trending toward the interrogation of limited amounts of genomic material to guide clinical and therapeutic decisions. The aim of this study was to investigate the minimum cellularity needed on cytologic smears for the identification of clinically relevant variants with next-generation sequencing (NGS). METHODS: Thirty cases of cytologically diagnosed, resection-proven primary lung adenocarcinoma were identified. Nineteen of the 30 cases were known to harbor actionable variants. One Diff-Quik (DQ)-stained slide and 1 Papanicolaou (Pap)-stained slide were selected from each case. Cases were categorized as containing fewer than 100 tumor cells, 100 to 500 tumor cells, or more than 500 tumor cells. NGS was performed on the Ion Torrent platform. RESULTS: NGS was successfully performed on all cell blocks and on 90% of the smears. Paired DQ and Pap smears showed similar cellularity, and cases that differed in cellularity were within 1 category of each other. The cases with more than 100 tumor cells had a 93% success rate; this was significantly different from the situation for cases with fewer than 100 tumor cells, which were successfully sequenced only 67% of the time. Overall, NGS was able to provide clinically relevant information for 83% of DQ smears and for 90% of Pap smears tested. CONCLUSIONS: The data show a significantly higher likelihood of successful NGS with cytologic smears with more than 100 tumor cells. There was a trend for a higher NGS success rate with Pap smears versus DQ smears. Cancer Cytopathol 2017;125:398-406. © 2017 American Cancer Society.