A Novel Scoring System for MYB RNA In Situ Hybridization Displays High Sensitivity and Specificity for Adenoid Cystic Carcinoma in a Clinical Setting

• Published in: Head & neck pathology (Totowa, N.J.) Vol. 18; no. 1; p. 51
• Main Authors: Bedell, Mariel, Lewis, Dale W., Seethala, Raja R.
• Format: Journal Article
• Language: English
• Published: New York Springer US 19.06.2024
• Subjects: Adult; Aged; Aged, 80 and over; Biomarkers, Tumor - analysis; Biomarkers, Tumor - genetics; Carcinoma, Adenoid Cystic - diagnosis; Carcinoma, Adenoid Cystic - genetics; Carcinoma, Adenoid Cystic - pathology; Dentistry; Female; Humans; In Situ Hybridization - methods; In Situ Hybridization, Fluorescence - methods; Male; Medicine; Medicine & Public Health; Middle Aged; Oral and Maxillofacial Surgery; Otorhinolaryngology; Pathology; Prospective Studies; Proto-Oncogene Proteins c-myb - genetics; Retrospective Studies; Sensitivity and Specificity; Young Adult; Logistic regression; Salivary gland neoplasms; gene; In situ; mRNA; Hybridization; Quantitative scoring; Adenoid cystic carcinoma; Myb gene
• ISSN: 1936-0568; 1936-0568
• DOI: 10.1007/s12105-024-01656-z

Background MYB RNA in situ hybridization (ISH) has emerged as a reliable and accessible marker to support adenoid cystic carcinoma (ACC) diagnosis, though still not well studied. Here, we report our results in a validation and prospective cohort to improve MYB RNA ISH diagnostic accuracy. Methods 79 cases (23 retrospective and 56 prospective) underwent MYB RNA ISH testing (44 ACC and 35 non-ACC). MYB RNA ISH results were initially interpreted based on previously established (original) scoring criteria. Weighted “i-scores”, percent positive tumor cells, percent tumor cells with large signals (% LS), and staining pattern (abluminal, diffuse, focal non-patterned, or negative) were inputs for logistic regression models. Final model performance characteristics were compared with original scoring criteria and MYB::NFIB FISH results. Results An abluminal pattern was characteristic and exclusive to ACC. All i-scores, % LS, and percent positive were significantly higher in ACC. Original scoring criteria yielded a 95.5% sensitivity (Sn), 68.6% specificity (Sp), and 83.5% accuracy. MYB::NFIB FISH yielded a 42.9% sensitivity, 100% specificity, and 60% accuracy. Optimizing for performance, simplicity, and minimal collinearity, our final model was defined as: abluminal pattern and/or % LS > 16.5%, which resulted in a 93.2% Sn, 97.1% Sp, and 94.9% accuracy for ACC diagnosis. False negatives included an ACC with striking tubular eosinophilia and a MYBL1::NFIB translocated ACC. One false positive exclusive to the final model was a nasopharyngeal carcinoma with MYB amplification. Conclusions MYB RNA ISH has a higher Sn than MYB::NFIB FISH while retaining high Sp. Our model provides improvements to specificity compared to original scoring criteria and highlight the importance of abluminal staining pattern and % LS. Nonetheless, alternate fusions remain key false negatives while rare non-ACC with other mechanisms of MYB activation may present as false positives.