Ancillary studies on cell blocks from fine needle aspiration specimens of salivary gland lesions: A multi‐institutional study

Is molecular testing of salivary gland FNA specimens ready for prime time?

With improvements in the molecular characterization of salivary gland neoplasms, fine‐needle aspiration specimens, including smears and cell blocks, are amenable to molecular testing for defining alterations, providing a specific diagnosis in many cases, and guiding management in a preoperative setting. Molecular testing can be particularly beneficial and complementary when used within the framework of the Milan system, as the results can further refine the risk of malignancy.

Doing more with less: integrating small biopsies in cytology practice

Cytopathologists are at the forefront of specimen acquisition during many different procedures while providing rapid on site evaluation (ROSE). This has added pressure to cytopathologists as more and more ancillary testing is being requested on smaller amounts of tissue. By focusing on the most common organ sites: lung, head and neck, and pancreas, there is a discussion of what the cytopathologist needs to know to triage tissue successfully. Finally, there is a discussion of the logistical aspects of integrating small biopsies into everyday practice.

Rapid on-site evaluation improves diagnostic performance of fine-needle aspiration cytology for salivary lesions: Comparison of data from two cancer centers in southern China

OBJECTIVES

To evaluate the diagnostic performance of Milan system for reporting salivary gland cytopathology (MSRSGC) in two southern China tertiary cancer centers and investigate the impact of rapid on-site evaluation (ROSE) on FNAC performance.

MATERIALS AND METHODS

Five hundred and forty-nine patients who underwent FNAC for salivary lesions with surgical follow-up from two centers were enrolled in this retrospective cohort study. All slides were recategorized using MSRSGC after consensus on diagnostic criteria for each category. The diagnostic performance of FNAC for salivary lesions was evaluated and compared and the impact of ROSE on FNAC performance was analyzed.

RESULTS

The distribution of cases per category based on the MSRSGC criteria in the whole series was as followed: ND 49 (8.9%), NN 76 (14.4%), BN 262 (47.7%), AUS 20 (3.6%), SUMP 43 (7.8%), SM 21 (3.8%), M 78 (14.2%). The SUMC series had significantly more ND distributions than JXCH did (16.2% vs. 0, p = .000). Risk of malignancy for each category in the total series was as followed: 42.9% for ND, 9.2% for NN, 3.8% for BN, 30.0% for AUS, 23.3% for SUMP, 81.0% for SM, and 94.9% for M. When ND and AUS/SUMP were excluded, the sensitivity, specificity, PPV, NPV, and accuracy were 84.0%, 97.1%, 89.9%, 95.1%, and 94.0%, respectively; sensitivity, specificity, PPV, NPV, and accuracy were comparable between the two centers.

CONCLUSIONS

FNAC using MSRSGC provides a good tool in preoperative evaluation for salivary lesions in southern China. ROSE improves its diagnostic performance by reducing the ratio of the ND category.

Quality of cell blocks prepared from residual pleural effusion and bronchial washing samples for immunocytochemistry

INTRODUCTION

Cell blocks (CBs) enable the long-term preservation of cytological samples. The aim of this study was to analyse the quality of CBs prepared from leftover fluid from lung adenocarcinoma pleural effusion samples and residual bronchial washing sediment for immunocytochemistry.

METHODS

The residual part of 455 lung adenocarcinoma pleural effusion samples and sediment from 384 bronchial washing samples were used to prepare CBs following the agarose method. The quality of CBs was evaluated based on the quantity of malignant cells in haematoxylin and eosin-stained slides and interpreted as optimal or insufficient for immunocytochemistry. Immunocytochemistry on CBs was performed using the Dako EnVision™ FLEX detection visualisation system. The CB results for TTF-1, ALK, and PD-L1 immunocytochemistry were compared with the corresponding cytological smears.

RESULTS

Among all CBs, 202 (44.4%) from leftover pleural effusion fluid and 85 (22.1%) from residual bronchial washing sediment had an optimal number of lung adenocarcinoma cells. Eight pleural effusion CBs were stained for TTF-1. Four pleural effusion and two bronchial washing CBs were stained for ALK and PD-L1. All tested pleural effusion CBs were confirmed positive for TTF-1 and negative for ALK. The PD-L1 tumour proportion score (TPS) was ≥ 50% in two pleural effusions. ALK was confirmed negative in bronchial washing CBs. One bronchial washing CB was interpreted as PD-L1-negative while the corresponding smear was positive (TPS ≥1%; 2%).

CONCLUSION

The CB results of TTF-1, ALK, and PD-L1 corresponded to the findings for the smears. The inclusion of CBs prepared from leftover fluid from pleural effusion samples and residual bronchial washing sediment in routine cytological practice could provide a source of high-quality material for immunocytochemistry in addition to smears and cytospins.

Validation of the Milan system for reporting salivary gland cytopathology: a single institution's 10-year experience

INTRODUCTION

Fine needle aspiration cytology is often used for the initial diagnosis and management of patients with salivary gland tumors. Because of its global usage, a consensus classification schema was devised in 2018 to initiate universal reporting of salivary gland cytology specimens, termed the Milan system for reporting salivary gland cytopathology (MSRSGC) and composed of distinct diagnostic categories. Few retrospective studies have been undertaken to review the MSRSGC within institutions.

MATERIALS AND METHODS

We analyzed salivary gland fine needle aspirations during a 10-year span from 2011 to 2021, categorized each cytology case to fit the MSRSGC, and subsequently reviewed the corresponding surgical resections, if indicated, to determine the rate of malignancy (ROM) and rate of neoplasia.

RESULTS

Our ROM was higher (>10%) for the following MSRSGC categories: non-neoplastic, atypia of undetermined significance, and suspicious for malignancy. Also, our data correlated well with the following MSRSGC categories: nondiagnostic, neoplasm-benign, salivary gland neoplasm of uncertain malignant, and malignant.

CONCLUSIONS

Although the data were indicative of the ROM for surgically resected salivary gland lesions, the ROM for non-neoplastic lesions could truly be lower given that most lesions in this category will not undergo surgical resection. Additionally, determination of the rate of neoplasia could a tool that could be used to further guide our clinical colleagues.

Application of the Milan system for reporting salivary gland cytopathology using cell blocks

The Milan system for reporting salivary gland cytopathology (MSRSGC) is a novel standardized classification tool for salivary gland cytology specimens based on the use of direct smears. Formalin-fixed paraffin-embedded (FFPE) cell blocks facilitate the use of ancillary studies, leading to improved diagnostic accuracy. However, the application of the MSRSGC with only cell blocks has not been well established. Consecutive cohort of all parotid gland cytology specimens between 01/01/2018 and 30/06/2021 was performed. All cytology specimens were processed into cell blocks only. Cytologic diagnoses were classified prospectively according to the MSRSGC categories. The risk of malignancy (ROM) for each diagnostic category and the diagnostic performance were calculated. A total of 230 FNA samples from 221 patients were identified, including 47% and 78.4% with surgical or clinical follow-up, respectively. The ROMs based on surgical follow-up for the non-diagnostic, non-neoplastic, AUS, neoplasm: benign, SUMP, SFM and malignant categories were 21.4%,0%,50%,0%,30%,100% and 100%, respectively. The ROMs based on the clinical follow-up for these categories were 7.3%,0%,37.3%,0%,27.3%,100% and 100%, respectively. Following surgical excision, all Milan IVa category samples were confirmed as benign, and all Milan V and VI category samples were confirmed as malignant. This study validates the application of the MSRSGC with the sole use of FFPE cell blocks. The diagnostic accuracy of MSRSGC is high and compares favorably to other institutions using traditional cytology assessment methods. Furthermore, FNA results using this technique enabled to provide optimal patient management based on the ROM of the different Milan system categories.

Secretory carcinoma of the salivary gland, a rare entity: An international multi-institutional study

BACKGROUND

Secretory carcinoma (SC) of the salivary gland is a rare entity with limited published literature on cytomorphology. The authors present the largest cohort to date of SC fine‐needle aspiration (FNA) cases.

METHODS

FNA cases of histologically confirmed SC were retrospectively retrieved from 12 academic institutions in the United States, Italy, Finland, and Brazil. The collated data included patient demographics, imaging findings, cytopathologic diagnoses according to the Milan System for Reporting Salivary Gland Cytopathology, cytomorphologic characteristics, and immunohistochemical/molecular profiles.

RESULTS

In total, 40 SCs were identified (male‐to‐female ratio, 14:26) in patients with a mean age of 52 years (age range, 13‐80 years). Ultrasound imagining revealed a hypoechoic, ovoid, poorly defined, or lobulated mass. The most common primary site was the parotid gland (30 of 40 tumors). Regional lymph node metastasis (9 patients) and distant metastasis (4 patients; brain, liver, lungs, and mediastinum) were noted. Two patients died of disease. FNA smears were cellular and demonstrated mainly large, round cells with intracytoplasmic vacuoles or granules and round‐to‐oval nuclei with smooth nuclear contour, minimal irregularities, and prominent nucleoli arranged predominantly in clusters, papillary formations, and single cells. The background was variable and contained inflammatory cells, mucin, or proteinaceous material. The diagnoses were malignant (19 of 38 tumors; 50%), suspicious for malignancy (10 of 38 tumors; 26%), salivary gland neoplasm of uncertain malignant potential (7 of 38 tumors; 18%), and atypia of undetermined significance (2 of 38 tumors; 6%) according to the Milan System for Reporting Salivary Gland Cytopathology. Two malignant cases (2 of 40 tumors; 5%) were metastases. The neoplastic cells were immunoreactive for S100 (23 of 24 tumors), mammaglobin (18 of 18 tumors), GATA‐3 (13 of 13 tumors), AE1/AE3 (7 of 7 tumors), and vimentin (6 of 6 tumors). ETV6‐NTRK3 fusion was detected in 32 of 33 tumors by fluorescence in situ hybridization (n = 32) and next‐generation sequencing (n = 1).

CONCLUSIONS

Familiarity with cytomorphologic features and the immunohistochemical/molecular profile of SC can enhance diagnostic accuracy.;

Secretory carcinoma of the salivary gland, which may manifest with diverse cytomorphology, mammaglobin expression, and ETV6 rearrangement or ETV6‐NTRK3 fusion, was investigated along with cytomorphologic features to facilitate an accurate diagnosis. The results indicated that familiarity with these features and with the immunohistochemical/molecular profile of secretory carcinoma of the salivary gland enhanced diagnostic accuracy.