Pleural metastasis from parotid secretory carcinoma: First report of morphology on effusion cytology,and role of pan-TRK immunohistochemistry |
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Authors: | Ria Mahendru MBBS Aanchal Kakkar MD Nicole Anne Cipriani MD Chetna Sarma MSc Vivek Ghosh MBBS Kavneet Kaur MD Subhash Gupta MD Anant Mohan MD PhD |
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Affiliation: | 1. Department of Pathology, All India Institute of Medical Sciences, New Delhi, India;2. Department of Pathology, The University of Chicago Medicine, Chicago, Illinois, USA;3. Department of Radiation Oncology, BRA IRCH, All India Institute of Medical Sciences, New Delhi, India;4. Department of Pulmonary, Critical Care and Sleep Medicine, All India Institute of Medical Sciences, New Delhi, India |
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Abstract: | Distant metastasis from salivary gland secretory carcinoma (SC) is rare, with lung and pleura being the most frequent site. While cytological features of SC on fine needle aspirates are well documented, its morphology in serous effusions has not been described. We describe the cytomorphological features on effusion cytology of two patients with ETV6::NTRK3 fusion-positive SC, who subsequently developed pleural metastases. Cytospin preparations of pleural fluid showed tightly cohesive, irregularly shaped and ball-like clusters of large tumor cells with scant to abundant uni- and multi-vacuolated cytoplasm. Nuclei were eccentrically placed, round to oval, vesicular, with finely granular chromatin, irregular nuclear membranes and conspicuous to prominent nucleoli. With these features, the tumors resembled an adenocarcinoma, indistinguishable from a lung primary. Cell blocks from both cases showed tumor fragments, some of which had the hollow appearance of transversely sectioned cell spheres as seen in lung and breast adenocarcinomas. Immunohistochemistry on cell blocks revealed nuclear pan-TRK positivity in both cases. Case 1 also showed focal mammaglobin staining, and TTF1 negativity. Pleural metastases from SC may mimic other adenocarcinomas. As targeted therapy, that is, selective TRK inhibitors are available for treatment of metastatic disease, NTRK3 fusion status is not only diagnostic, but also required to plan treatment. Pan-TRK immunohistochemistry serves as a viable cost-effective, easy to apply surrogate marker for NTRK3 fusion, particularly in diagnostic laboratories lacking easy access to molecular testing on cytological material. |
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Keywords: | cell block effusion cytology pleural effusion salivary gland targeted therapy |
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