Interobserver variability in cytopathology: How much do we agree?

Interobserver variability remains a major challenge for cytopathologists despite the development of standardized reporting and classification systems. Indeed, whereas moderate-to-good interobserver agreement is generally achievable when the differential diagnosis between benign and malignant entities is straightforward, high levels of variability make the diagnostic interpretation of atypical and suspicious samples not consistent. This review explores the landscape of interobserver agreement in cytopathology across different anatomical sites.

Acinic cell carcinoma mimicking Warthin's tumor: A diagnostic challenge on fine-needle cytology

The cytologic diagnosis of acinic cell carcinoma (ACC) can be challenging due to its polymorphous appearance and sharing cytomorphologic characteristics with other benign and malignant neoplasms as well as non-neoplastic diseases, even though various histomorphological aspects of ACC have been documented. We presented a 39-year-old female patient applied with right pre-auricular parotid swelling spreading infra-auricular region which was gradually increased in size for 3 months. Ultrasonographic examination revealed hypoechoic well-circumscribed mass with 17 × 22 × 29 mm size. Magnetic resonance imaging revealed intra-parotid solid lesion with cystic areas, slightly hypointense on T1 and hyperintense on T2 weighted images. The mass was pushing the retromandibular vein medially, still lateral to it in the caudal images, but in dumbbell-shape spreading through parapharyngeal space in superiorly cranial images. Fine-needle aspiration cytology was also performed with guidance of ultrasonography. The cytological examination of the lesion was characterized by the predominance of heterogeneous lymphoid cells, clusters of epithelial cells with a variety of cytologic appearances, including granular, transparent, vacuolated, and oncocytic, and the presence of numerous naked nuclei with a protein-like foamy background. Due to intense lymphocytic inflammation, it was considered as benign primary parotid tumor such as Warthin's tumor. The excision material was examined histopathologically. Immunohistochemical analysis showed that this carcinoma was positive for DOG1, SOX10, cytokeratin 7 and negative for mammaglobin. This salivary gland tumor was reported as a rare variant of ACC with lymphoid-rich stroma. To improve the diagnostic accuracy, various morphological aspects of ACC should be considered in the pathological practice.

MASC Gets UNMASKED: Visiting a Rare Tumor with Emphasis on Cytomorphological Features

Background

Secretory carcinoma (SC) is a newly described entity which has been often misdiagnosed earlier as acinic cell carcinoma on cytology. Diagnosing SC was initially based upon identifying the ETV6:NTRK3 fusion gene with the help of fluorescence in situ hybridization (FISH). Lately, with more knowledge of the reliable histomorphology, cytology, and immunohistochemistry features, definitive diagnosis can be confidently made without the help of FISH in almost every case.

Materials and Methods

Six histologically confirmed cases of SC were studied. The cytology slides of all the six cases were retrieved and reviewed to identify the characteristic features which could have helped in raising the possibility of SC on fine needle aspiration cytology itself. Cell blocks were also studied, wherever available.

Results

Patients were all male with average age of 35.2 years. The six cases in the current study demonstrated at least focal cytoplasmic vacuolization of varying sizes, papillae formations, and bland nuclear features on fine needle aspirate smears. It was also seen that S-100 and mammaglobin immunohistochemistry (IHC) are very helpful in confirming the diagnosis.

Conclusions

The results of the current study highlight the cytomorphological features which may help in clinching the diagnosis SC on cytology itself. They also highlight certain cytological features which help to rule out the other differential diagnoses.

Application of the Milan System for Reporting Salivary Gland Lesions and Its Cytohistological Correlation for Risk Stratification: A Single-Institution Experience

INTRODUCTION

 Salivary gland tumors are known to have a heterogeneous profile with variable clinical presentation and a wide variety of histological subgroups of prognostic significance. Immunocytochemical markers that aid in the diagnosis and characterization of the cell type of origin are critical for this heterogeneous group of malignancies.

AIMS AND OBJECTIVES

To study the application of The 'Milan System' for Reporting Salivary Gland Cytology and the diagnostic utility of a panel of immunocytochemical markers in the diagnosis of salivary gland neoplasms and their cytohistological correlation for their risk stratification.

MATERIALS AND METHODS

This was a prospective study carried out in which a total of 60 patients were enrolled in the study. Fine-needle aspiration cytology (FNAC) smears and cell blocks were prepared with standard techniques and staining procedures. Immunocytochemistry (ICC) was performed on cell block sections by immunoperoxidase procedure. Immunocytochemical (ICC) stains were used for the differentiation of the lesions in cell blocks. Histopathology was also studied if the patient underwent excision of salivary gland lesions.

DISCUSSION AND RESULTS

Almost 60 cases were studied under FNAC and cell block evaluation, as well as ICC, among those five (8.33%) samples were inadequate, eight (13.3%) were non-neoplastic, 27 (45%) were benign, one (1.7%) was neoplasm with uncertain malignancy potential, one (1.7%) was suspected of malignancy, and 19 (31.7%) were malignant. The histopathological diagnosis was confirmed in 47 cases. Of these, 24 (51.1%) were benign and 23 (48.9%) were malignant. The malignancy rate for Milan Categories I, II, III, IVa, IVb, V, and VI was 0%, 0%, 100%, 24%, 50%, 80%, and 84.6%, respectively. The study showed that malignancy risk stratification could be further improved by using cell block with immunocytochemistry as a complementary diagnostic modality.

CONCLUSIONS

The present study was carried out to assess the usefulness of the Milan system to report salivary gland cytology results. Thus, the findings of the present study show that the Milan system is helpful in stratifying the risk of malignancy in salivary gland tumors.

Atypia of undetermined significance in the Milan System for Reporting Salivary Gland Cytopathology: Cystic versus non-cystic masses

The term "Atypia" has been employed to describe a wide spectrum of cytomorphologic features associated with reactive/inflammatory processes as well as those suspicious for neoplasms in cytology. Similar to other cytopathology reporting systems, the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) has reserved the atypical category for cytology specimens lacking quantitative and/or qualitative cytomorphologic features to be diagnosed with confidence as either non-neoplastic or neoplastic. In MSRSGC, the atypical category is associated with a risk of malignancy and recommendation for clinical management. In this review, we discuss the value of atypical diagnostic category of MSRSGC in both cystic and non-cystic salivary gland lesions by evaluating our institutional case cohort.

Acinic cell carcinoma of the salivary gland associated with lymphoid-rich stroma. A diagnostic dilemma on cytology: Study of two cases

A lymphoid-rich stroma is a common finding in salivary gland tumors. Several reports documented this association with acinic cell carcinoma (ACC). However, cytologic studies reporting this phenomenon are rare and mainly confined to sporadic single case reports. We present the cytologic features of two cases of ACCs of the parotid gland displaying a lymphoid-rich background and discuss the cytologic differential diagnoses of this uncommon ACC variant.

Risk stratification of salivary gland cytology utilizing the Milan system of classification

BACKGROUND

The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is based on risk stratification. Our study is a retrospective review of salivary gland fine needle aspiration cytology (FNAC) with the goal of determining the risk of malignancy (ROM) in each of the categories proposed by the MSRSGC.

METHODS

FNAC of salivary gland lesions with corresponding surgical resection specimens were retrieved over a 5-year period. Metastatic tumors were excluded. BothFNAC and corresponding surgical resections were reviewed blindly and classified as per criteria published by the MSRSGC. The ROM for each of the diagnostic categories was determined and compared with the ROM published by the MSRSGC.

RESULTS

The total number of entities and ROM in 199 reviewed cases were as follows: Nondiagnostic 18 (9.2%) (ROM 0%), non-neoplastic 4(2%) (ROM 0%), atypia of undetermined significance (AUS) 12(6%) (ROM 33%), benign neoplasm 118(59.2%) (ROM 0.8%), salivary gland neoplasm of uncertain malignant potential (SUMP) 22(11%) (ROM 40.9%), suspicious for malignancy 3(1.5%) (ROM 100%), malignant 22(11%) (ROM 100%).

CONCLUSION

The ROM reported in our study was mostly concordant with ROM published by the MSRSGC. This classification is helpful for the management of categories; nondiagnostic, non-neoplastic, benign neoplasm, suspicious for malignancy and malignant. The management is not standardized for the category, salivary gland neoplasm of uncertain malignant potential, as clinical information plays an important role in planning surgical procedures at an individual basis. Further studies will need to be performed using this new classification to help define appropriate management and predict ROM more accurately.

Feasibility of a novel classification for parotid gland cytology: A retrospective review of 512 cytology reports taken from 4 United Kingdom general hospitals

BACKGROUND

A novel classification for parotid cytology has been previously proposed. The purpose of this study was to assess the feasibility and clinical relevance of this classification.

METHOD

Between 2010 and 2013, cytology reports from 4 United Kingdom general hospitals were retrospectively classified and compared to histological and clinical outcomes.

RESULTS

Based on the cytology reports of 512 patients, we revised our previous "P" system to a "Sal" (salivary) classification to encompass all cytologic outcomes. The percentage of patients with a final diagnosis of malignancy according to each category heading were: Sal 1 (inadequate) 7.9%; Sal 2I (nonneoplastic) 10%; Sal 2N (benign neoplastic) 1.4%; Sal 3 (atypical) 20.4%; Sal 4 (suspicious) 52.6%; Sal 5P (primary salivary gland malignancy) 71.4%; Sal 5NOS (malignancy not otherwise specified) 100%; and Sal 5M (metastasis) 91.7%.

CONCLUSION

By stratifying the probability of encountering a malignant neoplasm, the classification could guide clinical management decisions. A future prospective study is warranted. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1708-1716, 2016.