1. Histologic Classification and Molecular Signature of Polymorphous Adenocarcinoma (PAC) and Cribriform Adenocarcinoma of Salivary Gland (CASG): An International Interobserver Study.
- Author
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Xu B, Barbieri AL, Bishop JA, Chiosea SI, Dogan S, Di Palma S, Faquin WC, Ghossein R, Hyrcza M, Jo VY, Lewis JS Jr, Lozada JR, Michal M, Pareja FG, Perez-Ordonez B, Prasad ML, Purgina B, Reis-Filho JS, Scognamiglio T, Sebastiao APM, Seethala RR, Skálová A, Smith SM, Tekkeşin MS, Thompson LDR, Wasseman JK, Wenig BM, Weinreb I, and Katabi N
- Subjects
- Adenocarcinoma classification, Biopsy, Canada, DNA Mutational Analysis, Europe, Gene Fusion, Genetic Predisposition to Disease, Humans, In Situ Hybridization, Fluorescence, Mutation, Observer Variation, Predictive Value of Tests, Real-Time Polymerase Chain Reaction, Reproducibility of Results, Salivary Gland Neoplasms classification, United States, Adenocarcinoma genetics, Adenocarcinoma pathology, Biomarkers, Tumor genetics, Salivary Gland Neoplasms genetics, Salivary Gland Neoplasms pathology
- Abstract
Polymorphous adenocarcinoma (PAC) shows histologic diversity with streaming and targetoid features whereas cribriform adenocarcinoma of salivary gland (CASG) demonstrates predominantly cribriform and solid patterns with glomeruloid structures and optically clear nuclei. Opinions diverge on whether CASG represents a separate entity or a variant of PAC. We aimed to assess the level of agreement among 25 expert Head and Neck pathologists in classifying these tumors. Digital slides of 48 cases were reviewed and classified as: PAC, CASG, tumors with ≥50% of papillary architecture (PAP), and tumors with indeterminate features (IND). The consensus diagnoses were correlated with a previously reported molecular alteration. The consensus diagnoses were PAC in 18/48, CASG in16/48, PAP in 3/48, and IND in 11/48. There was a fair interobserver agreement in classifying the tumors (κ=0.370). The full consensus was achieved in 3 (6%) cases, all of which were classified as PAC. A moderate agreement was reached for PAC (κ=0.504) and PAP (κ=0.561), and a fair agreement was reached for CASG (κ=0.390). IND had only slight diagnostic concordance (κ=0.091). PAC predominantly harbored PRKD1 hotspot mutation, whereas CASG was associated with fusion involving PRKD1, PRKD2, or PRKD3. However, such molecular events were not exclusive as 7% of PAC had fusion and 13% of CASG had mutation. In conclusion, a fair to moderate interobserver agreement can be achieved in classifying PAC and CASG. However, a subset (23%) showed indeterminate features and was difficult to place along the morphologic spectrum of PAC/CASG among expert pathologists. This may explain the controversy in classifying these tumors.
- Published
- 2020
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