Immunohistochemistry with a pan-TRK antibody distinguishes secretory carcinoma of the salivary gland from acinic cell carcinoma.

Autor: Hung YP; Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.; Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA., Jo VY; Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA., Hornick JL; Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
Jazyk: angličtina
Zdroj: Histopathology [Histopathology] 2019 Jul; Vol. 75 (1), pp. 54-62. Date of Electronic Publication: 2019 May 16.
DOI: 10.1111/his.13845
Abstrakt: Aims: Secretory carcinoma (previously known as mammary analogue secretory carcinoma) is characterised by ETV6 rearrangements, most often ETV6-NTRK3 fusion. Given its histological overlap with other salivary gland tumours, secretory carcinoma can be difficult to diagnose without genetic confirmation. A recently developed pan-TRK antibody shows promise for identifying tumours with NTRK fusions. The aim of this study was to evaluate the utility of pan-TRK immunohistochemistry in distinguishing secretory carcinoma from mimics.
Methods and Results: We examined whole-tissue sections from 86 tumours, including 14 secretory carcinomas (12 parotid primaries and one buccal primary, and one metastasis; five with ETV6 rearrangement confirmed by fluorescence in-situ hybridisation, and one with ETV6-NTRK3 fusion and one with ETV6-RET fusion detected by targeted sequencing), 14 acinic cell carcinomas, 18 polymorphous adenocarcinomas, 20 low-grade mucoepidermoid carcinomas, and 20 pleomorphic adenomas. Immunohistochemistry was performed with a pan-TRK rabbit monoclonal antibody. Pan-TRK staining was detected in nine (64%) secretory carcinomas, all with a nuclear pattern and four with diffuse staining (>50% of cells). Among other tumour types, pan-TRK immunoreactivity was observed in all (100%) pleomorphic adenomas (particularly myoepithelial cell-rich, myxoid areas), 15 (83%) polymorphous adenocarcinomas, and four (20%) low-grade mucoepidermoid carcinomas, all with predominantly membranous/cytoplasmic immunoreactivity; only six cases showed focal (<10%) nuclear staining. All acinic cell carcinomas were entirely negative.
Conclusions: Although pan-TRK expression is not entirely sensitive or specific for secretory carcinoma, nuclear staining distinguishes secretory carcinoma from mimics. Acinic cell carcinomas are negative for pan-TRK, though membranous expression of TRK is common in other salivary gland neoplasms. The lack of pan-TRK immunoreactivity in a subset of secretory carcinomas may suggest non-NTRK fusion partners.
(© 2019 John Wiley & Sons Ltd.)
Databáze: MEDLINE
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