Evaluation of diagnostic accuracy and a practical algorithmic approach for the diagnosis of renal masses by FNA

Spectrum of Renal Tumors Other Than Renal Cell Carcinoma with Emphasis on Cytomorphological, Immunohistochemical, and Cytogenetic Study

Background

The role of fine needle aspiration cytology (FNAC) in the diagnosis of renal malignancies is established and has been getting more precise and important over a period of time. Knowledge of the pathology of uncommon renal neoplasms along with radiological and clinical correlations often aids in correct diagnosis.

Aims

The present study aims to describe the cytomorphological and immunohistochemical findings in the varied spectrum of renal tumors, other than renal cell carcinomas (RCC).

Materials and Methods

Data of 238 cases of ultrasound-guided renal FNAC performed in our tertiary cancer institute over 4 years were collected from the department registry. All nondiagnostic cases and cases diagnosed as RCC were excluded from the study, so 57 cases of renal tumors were reviewed along with the cell blocks and ancillary studies.

Results

Out of the 57 cases, 35 cases were primary renal neoplasms, which included renal oncocytoma (3.5%), angiomyolipoma (3.5%), rhabdoid tumor (1.8%), Wilms tumor (28.0%), Ewing sarcoma (3.5%), urothelial carcinoma (8.8%), and small round cell tumor unclassified (12.3%). Twenty two cases were metastatic tumors, which included hematolymphoid neoplasm (14%) and metastatic carcinomas (24.6%) from various other primary carcinomas.

Conclusion

Our study shows that renal FNAC is safe and fairly accurate in diagnosing a wide spectrum of renal tumors and has high diagnostic accuracy, when performed along with cell block and immunohistochemistry. Awareness of the pathology of uncommon renal tumors along with relevant clinical history and radiological findings may aid in identifying the type of tumor for further appropriate management.

A systematic review on performance characteristics of FNA of renal lesions: It is time for a standardized classification system

BACKGROUND

The incidence of renal tumors has steadily increased over the past decade. In this study, the authors performed a systematic review and analysis of the literature on renal fine-needle aspiration (FNA) to determine its performance and explore whether a standardized classification system can be used for reporting renal FNA cytology.

METHODS

A systematic search of published articles on renal FNA was conducted. The data on FNA and histologic diagnosis were extracted and categorized, and the risk of malignancy was calculated. Different scenarios were used to estimate FNA performance statistics.

RESULTS

Of the 3766 potentially relevant studies, 23 met the inclusion criteria of the study. The 2231 FNA cases included were re-categorized according to the classification system, rendering 142 (6.36%) nondiagnostic, 270 (12.1%) nonneoplastic, 271 (12.14%) benign neoplasm, 65 (2.91%) renal neoplasm with unknown malignant potential, oncocytic type, 25 (1.12%) atypia of undetermined significance, 60 (2.68%) suspicious for malignancy, and 1398 (62.66%) malignant FNA diagnoses. The risk of malignancy in these cases was 65.4%, 18.1%, 16.6%, 16.9%, 60%, 73.3%, and 96.9%, respectively. According to the classification system, the study indicated that the accuracy of renal FNA was between 91% and 95%, the sensitivity was 90.9%-96.7%, and the specificity was 82%-92% in different scenarios.

CONCLUSIONS

There is a need for a standardized reporting in renal cytology that will improve the sensitivity and accuracy of renal cytology, reduce the rate of indeterminate diagnoses, and alter the management strategies of renal lesions. Based on the available literature, a new reporting system is proposed, including categories with an associated risk of malignancy.

Risk of malignancy in renal biopsy: A review

The risks of malignancy for cytologic categories in renal biopsy specimens differ from the risks in most other sites. There are obvious areas in which cytopathologists can do better at classifying these cases, and the routine use of immunohistochemistry and core-needle biopsy may improve the accuracy of the classification of these specimens.

Utility of cytopathologic diagnosis of adult solid renal lesions: An academic Institution's 10-year experience

BACKGROUND

Fine needle aspiration (FNA) and/or needle core biopsy (NCB) are increasingly used for managing patients with renal lesions, especially small renal masses (SRMs). One of the treatment options for SMRs is active surveillance. Hence, accurate diagnosis of renal lesions is critical for treatment planning. The aim of this study is to investigate the utility of FNA and/or NCB in the diagnosis of adult renal lesions at our institute.

MATERIALS AND METHODS

Laboratory information system was queried over a period of 10 years (2011-2020) to identify cases of FNA and/or NCB with touch preparation (TP) of adult renal masses. Patient demographics, cytopathologic diagnoses, ancillary tests and follow-up surgical resection data were reviewed and correlated.

RESULTS

A total 138 cases from 138 patients (male = 80, female = 58) were identified. Sixty-one (44.20%) cases had FNA and NCB, 48 (34.78%) had NCB only and 29 (21.01%) had FNA only. 118 (85.50%) cases had definitive diagnoses and 13 (9.42%) had indeterminant diagnoses and seven cases were non-diagnostic (5.07%). Most common benign and malignant diagnoses were oncocytoma and clear cell renal cell carcinoma (CCRCC). 41/138 (29.71%) cases had follow-up resection. There were no false positive or false negative cases. Subtyping was feasible in majority cases with only 3/138 (2.17%) misclassified cases.

CONCLUSIONS

Majority of renal masses (85.50%) had definitive cytology diagnoses. Only three had misclassification. FNA and/or NCB are useful methods in diagnosing and subclassifying adult renal masses and showed high accuracy (91.89%) when compared to surgical resections.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.