Adenocarcinoma cells in effusion cytology as a diagnostic pitfall with potential impact on clinical management: a case report with brief review of immunomarkers.

Distinguishing metastatic carcinoma cells from reactive mesothelial cells in effusion samples is often challenging based on morphology alone. Metastatic carcinoma cells in fluid samples may mimic reactive mesothelial cells due to overlapping cytological features. We report a case of a pleural effusion in a 51-year-old female patient with a medical history significant for bilateral ovarian tumors and peritoneal implants diagnosed as serous tumor of borderline malignant potential. The effusion was composed almost entirely of adenocarcinoma cells that morphologically mimicked reactive mesothelial cells. The diagnosis of metastatic adenocarcinoma was made after a wide immunostaining panel of antibodies. Recognizing metastatic adenocarcinoma cells in effusion samples can be challenging and an accurate diagnosis may have significant impact on clinical management as demonstrated by this case.

Next-generation sequencing-based multi-gene mutation profiling of solid tumors using fine needle aspiration samples: promises and challenges for routine clinical diagnostics.

Increasing use of fine needle aspiration for oncological diagnosis, while minimally invasive, poses a challenge for molecular testing by traditional sequencing platforms due to high sample requirements. The advent of affordable benchtop next-generation sequencing platforms such as the semiconductor-based Ion Personal Genome Machine (PGM) Sequencer has facilitated multi-gene mutational profiling using only nanograms of DNA. We describe successful next-generation sequencing-based testing of fine needle aspiration cytological specimens in a clinical laboratory setting. We selected 61 tumor specimens, obtained by fine needle aspiration, with known mutational status for clinically relevant genes; of these, 31 specimens yielded sufficient DNA for next-generation sequencing testing. Ten nanograms of DNA from each sample was tested for mutations in the hotspot regions of 46 cancer-related genes using a 318-chip on Ion PGM Sequencer. All tested samples underwent successful targeted sequencing of 46 genes. We showed 100% concordance of results between next-generation sequencing and conventional test platforms for all previously known point mutations that included BRAF, EGFR, KRAS, MET, NRAS, PIK3CA, RET and TP53, deletions of EGFR and wild-type calls. Furthermore, next-generation sequencing detected variants in 19 of the 31 (61%) patient samples that were not detected by traditional platforms, thus increasing the utility of mutation analysis; these variants involved the APC, ATM, CDKN2A, CTNNB1, FGFR2, FLT3, KDR, KIT, KRAS, MLH1, NRAS, PIK3CA, SMAD4, STK11 and TP53 genes. The results of this study show that next-generation sequencing-based mutational profiling can be performed on fine needle aspiration cytological smears and cell blocks. Next-generation sequencing can be performed with only nanograms of DNA and has better sensitivity than traditional sequencing platforms. Use of next-generation sequencing also enhances the power of fine needle aspiration by providing gene mutation results that can direct personalized cancer therapy.

Kba.62 and S100 protein expression in cytologic samples of metastatic malignant melanoma.

The diagnosis of melanoma can be challenging, especially in metastatic lesions, due to the ability of melanoma cells to morphologically mimic carcinoma, sarcoma and even lymphoma cells. Moreover, melanomas can exhibit negative immunostaining for the melanoma markers HMB-45 and MART-1/Melan-A, often used in the diagnosis of this tumor. KBA.62 is a recently described antibody that reacts with benign and malignant melanocytic proliferations. In this study, we report our experience with KBA.62 and S100 protein immunostaining in the diagnosis of metastatic melanoma on fine-needle aspiration and effusion samples. We reviewed 60 cytology samples from 58 patients with metastatic melanoma. Our results showed that KBA.62 stained 75% of the cases and S100 protein 87% of the cases. KBA.62 and S100 protein stained the majority of metastatic melanomas that were negative for HMB-45 and MART-1; KBA.62 stained 73% of the cases and S100 protein 73% of the cases. The majority (85%) of the cases negative for HMB-45 and MART-1 were positive for KBA.62 and/or S100 protein. Additionally, we also observed that KBA.62 staining was positive in the majority of epithelioid and spindle cell type melanoma cells. In conclusion, the performances of KBA.62 and S100 protein were similar and both markers are useful in the diagnosis of metastatic melanoma in cytology material, especially when the tumor cells lack expression of HMB-45 and MART-1.

EGFR and KRAS mutation analysis in cytologic samples of lung adenocarcinoma enabled by laser capture microdissection.

The discovery of activating mutations in EGFR and KRAS in a subset of lung adenocarcinomas was a major advance in our understanding of lung adenocarcinoma biology, and has led to groundbreaking studies that have demonstrated the efficacy of tyrosine kinase inhibitor therapy. Fine-needle aspirates and other cytologic procedures have become increasingly popular for obtaining diagnostic material in lung carcinomas. However, frequently the small amount of material or sparseness of tumor cells obtained from cytologic preparations limit the number of specialized studies, such as mutation analysis, that can be performed. In this study we used laser capture microdissection to isolate small numbers of tumor cells to assess for EGFR and KRAS mutations from cell block sections of 19 cytology samples from patients with known lung adenocarcinomas. We compared our results with previous molecular assays that had been performed on either surgical or cytology specimens as part of the patient's initial clinical work-up. Not only were we able to detect the identical EGFR or KRAS mutation that was present in the patient's prior molecular assay in every case, but we were also able to consistently detect the mutation from as few as 50 microdissected tumor cells. Furthermore, isolating a more pure population of tumor cells resulted in increased sensitivity of mutation detection as we were able to detect mutations from laser capture microdissection-enriched cases where the tumor load was low and traditional methods of whole slide scraping failed. Therefore, this method can not only significantly increase the number of lung adenocarcinoma patients that can be screened for EGFR and KRAS mutations, but can also facilitate the use of cytologic samples in the newly emerging field of molecular-based personalized therapies.

Inactivation of LLC1 gene in nonsmall cell lung cancer.

Serial analysis of gene expression studies led us to identify a previously unknown gene, c20orf85, that is present in the normal lung epithelium but absent or downregulated in most primary nonsmall cell lung cancers and lung cancer cell lines. We named this gene LLC1 for Low in Lung Cancer 1. LLC1 is located on chromosome 20q13.3 and has a 70% GC content in the promoter region. It has 4 exons and encodes a protein containing 137 amino acids. By in situ hybridization, we observed that LLC1 message is localized in normal lung bronchial epithelial cells but absent in 13 of 14 lung adenocarcinoma and 9 out of 10 lung squamous carcinoma samples. Methylation at CpG sites of the LLC1 promoter was frequently observed in lung cancer cell lines and in a fraction of primary lung cancer tissues. Treatment with 5-aza deoxycytidine resulted in a reduced methylation of the LLC1 promoter concomitant with the increase of LLC1 expression. These results suggest that inactivation of LLC1 by means of promoter methylation is a frequent event in nonsmall cell lung cancer and may play a role in lung tumorigenesis.