Cytological preparations for molecular analysis: A review of technical procedures, advantages and limitations for referring samples for testing.

Minimally invasive procedures such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) must yield not only good quality and quantity of material for morphological assessment, but also an adequate sample for analysis of molecular markers to guide patients to appropriate targeted therapies. In this context, cytopathologists worldwide should be familiar with minimum requirements for refereeing cytological samples for testing. The present manuscript is a review with comprehensive description of the content of the workshop entitled Cytological preparations for molecular analysis: pre-analytical issues for EBUS TBNA, presented at the 40th European Congress of Cytopathology in Liverpool, UK. The present review emphasises the advantages and limitations of different types of cytology substrates used for molecular analysis such as archival smears, liquid-based preparations, archival cytospin preparations and FTA (Flinders Technology Associates) cards, as well as their technical requirements/features. These various types of cytological specimens can be successfully used for an extensive array of molecular studies, but the quality and quantity of extracted nucleic acids rely directly on adequate pre-analytical assessment of those samples. In this setting, cytopathologists must not only be familiar with the different types of specimens and associated technical procedures, but also correctly handle the material provided by minimally invasive procedures, ensuring that there is sufficient amount of material for a precise diagnosis and correct management of the patient through personalised care.

The impact of repeat FNA in non-diagnostic and indeterminate thyroid nodules: A 5-year single-centre experience.

INTRODUCTION: FNA is a well-established method for the preoperative diagnosis of thyroid nodules, but limitations still reside among non-diagnostic and indeterminate samples. The objective of the present study was to assess the impact of repeat FNA in thyroid nodules primarily classified as non-diagnostic and indeterminate, with the evaluation of the diagnostic resolution rate after the reassessment of the nodule. METHODS: We retrospectively collected all cases of thyroid FNA at our institution in the last 5 years that had one or more repeat aspirations of the same nodule, calculating the percentage of samples with change in the diagnostic category. Additional collected data included sex, age and interval between the repeat aspirations. RESULTS: One hundred and seventy-eight specimens from 167 patients (140 female, 27 male) with a median age of 56 years (range 11-90) were included in the study. Among the 86 cases primarily classified as non-diagnostic, 25 (29.1%) remained in the same category after the first reassessment and only 18 (20.9%) after the second repeat aspiration. Among the 40 indeterminate cases, only 10 (25%) retained their status after the second aspiration, with no change after the third assessment. CONCLUSION: Repeat aspiration of non-diagnostic and indeterminate thyroid nodules had a positive impact in both groups, with diagnostic resolution rates of 80% and 75%, respectively. The present study therefore endorses the use of such strategy for the initial follow-up of nodules with no definite diagnosis, especially in low-resource centres with limited access to modern molecular technologies.

Use of cytological samples of metastatic melanoma for ancillary studies.

OBJECTIVE: Fine needle aspiration (FNA) is widely used in the diagnosis of metastatic melanoma, both at initial presentation and in the setting of recurrent disease. The purpose of this study was to evaluate the performance of confirmatory immunohistochemistry (IHC) and molecular analysis of the BRAF mutation in cytological preparations of metastatic melanoma. METHODS: A 2-year retrospective review of pathology reports was performed on cytological samples of metastatic melanoma at the University Health Network (Toronto, Canada) and the Santa Casa Medical School (Sao Paulo, Brazil). IHC was performed on cell block sections prepared from formalin-fixed, fresh samples or residuum of CytoLyt/PreservCyt post-fixed in formalin. BRAF V600E/K mutations were assessed by amplification refractory mutation system (ARMS) analysis. RESULTS: A total of 104 samples (94 FNAs and 10 fluids) from 83 patients (20 women, 63 men) were included. IHC was attempted in 43 cases (41.3%) and successful in 41 (95.3%). The panel number of antibodies ranged from 1 to 15 (median 3). The most frequently used melanoma markers included HMB-45, melanoma cocktail and S100 protein, used in 25 (58.1%), 23 (53.5%) and 18 samples (41.9%). Thirty cases (69.8%) used three or fewer markers. The BRAF V600E/K mutation was tested in eight samples, being successful in seven (87.5%) and positive in three (37.5%). CONCLUSIONS: Cytological samples are a reliable and sufficient source for IHC and subsequent molecular analysis, allowing a reduced diagnostic time and rapid, appropriate treatment options in patients with advanced melanoma.

Epstein-Barr virus encoded RNA detected by in situ hybridization using cytological preparations.

OBJECTIVE: Detection of Epstein-Barr virus (EBV) status might help in the diagnosis of EBV-related neoplasms. The rate of successful assays for the detection of EBV-infected cells in cytological preparations has not been fully explored. Our aims were to examine the rate of successful in situ hybridization (ISH) assays for EBV-encoded RNA (EBER) in cytological specimens and to explore reasons for failure. METHODS: An electronic search selected cases with ISH-EBER assays performed on cytological preparations during a 10-year period. Data regarding patient age, gender and immune status, sample type and site, type of preparation, ISH-EBER results, immunophenotyping and immunohistochemistry results, final diagnosis and correspondent histopathological samples were retrieved. RESULTS: Sixty specimens from 58 patients with diagnoses of lymphoproliferative disorder (n = 35), carcinoma (n = 24) and sarcoma (n = 1) were identified. ISH-EBER assays were performed on 50 cell block sections and on 10 cytospin preparations, with 22 positive and 32 negative results. Six tests (four cytospins and two cell block sections) failed owing to loss of material during the assay and background staining, with an overall failure rate of 10% and 4% if cytospins were excluded. Assays were performed on 13 cytology and surgical specimens from the same site, with only one discrepant result. CONCLUSIONS: Cell block sections had more successful ISH-EBER assays when compared with cytospins. Reasons for failure were loss of material on the slide and background staining. A high concordance rate with surgical specimens emphasizes the usefulness of cytological samples for determining EBV status in patients with exhausted or no histological material available.