Distinguishing synchronous and metachronous primary lung adenocarcinomas from adenocarcinomas with intrapulmonary metastasis is essential for optimal patient management. In this study, multiple lung adenocarcinomas occurring in the same patient were evaluated using comprehensive histopathologic evaluation supplemented with molecular analysis. The cohort included 18 patients with a total of 52 lung adenocarcinomas. Eleven patients had a new diagnosis of multiple adenocarcinomas in the same lobe (n=5) or different lobe (n=6). Seven patients had a history of lung cancer and developed multiple new tumors. The final diagnosis was made in resection specimens (n=49), fine needle aspiration (n=2), and biopsy (n=1). Adenocarcinomas were non-mucinous, and histopathologic comparison of tumors was performed. All tumors save for one were subjected to ALK gene rearrangement testing and targeted Next Generation Sequencing (NGS). Using clinical, radiologic, and morphologic features, a confident conclusion favoring synchronous/metachronous or metastatic disease was made in 65% of patients. Cases that proved challenging included ones with more than three tumors showing overlapping growth patterns and lacking a predominant lepidic component. Genomic signatures unique to each tumor were helpful in determining the relationship of multiple carcinomas in 72% of patients. Collectively, morphologic and genomic data proved to be of greater value and achieved a conclusive diagnosis in 94% of patients. Assessment of the genomic profiles of multiple lung adenocarcinomas complements the histological findings, enabling a more comprehensive assessment of synchronous, metachronous, and metastatic lesions in most patients, thereby improving staging accuracy. Targeted NGS can identify genetic alterations with therapeutic implications.

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.

Validation of RNA-based NGS assays for the detection of therapeutically targetable gene fusions is challenging. Here, we report systematic validation and quality control monitoring of our targeted fusion panel for the detection of 17 clinically relevant fusion transcripts across several tumor types. We implemented this RNA Fusion Panel as a reflex test for tumors lacking DNA driver mutations. Forty-four formalin-fixed, paraffin-embedded (FFPE) or fresh-frozen lung, brain, soft tissue and skin tumors were used to determine the accuracy of the assay. Additional fusion-positive specimens and a calibrated reference standard were used to establish the precision, reproducibility and sensitivity of the assay. All aspects of the validation, including quality control metrics, were performed according to New York State guidelines. For the RNA fusion panel, accuracy, reproducibility and precision studies were above 99%. Reproducibility and sensitivity studies with the reference standard were helpful in identifying inconsistencies. The limit of detection for most RNA fusion transcripts was 50 copies. Application of the RNA fusion assay as a reflex test to 450 tumor samples lacking DNA driver mutations resulted in a 10% increase in diagnostic yield with minimal additional processing time. The validated RNA fusion panel provides clinical utility in therapy selection for patients with solid tumors. By using a sequential testing approach, the RNA fusion assay complements the DNA hotspot assay in identifying clinically relevant variants across many tumor types with minimal additional increase in processing time.

Benign metastasizing leiomyoma (BML) is a rare benign smooth muscle neoplasm that originates in the uterus and metastasizes to distant sites—most commonly the lungs. BMLs are often found incidentally in patients with a history of uterine leiomyoma(s) and tend to be indolent. Occasionally they may be symptomatic and rarely follow an aggressive clinical course. We report an unusual case of BML presenting in a 46-year-old woman as a miliary nodular pattern bilaterally in the lungs and progressive respiratory failure. Her past medical history was significant for uterine “leiomyomas” of at least 9 years' duration. Post mortem histologic evaluation of the uterine and lung lesions revealed benign smooth muscle neoplasms (leiomyomas and BMLs, respectively), and molecular analyses demonstrated identical clonal MED12 mutation, though with greater mutant allelic frequency in the uterus. We document a rare aggressive clinical course in a patient with BML, which presented as a miliary radiologic pattern mimicking an infectious etiology or interstitial lung disease.