MASC gets UNMASKED: Visiting a rare tumor with emphasis on cytomorphological features

Background: Secretory carcinoma (SC) is a newly described entity which has been often misdiagnosed earlier as acinic cell carcinoma on cytology. Diagnosing SC was initially based upon identifying the ETV6:NTRK3 fusion gene with the help of fluorescence in situ hybridization (FISH). Lately, with more knowledge of the reliable histomorphology, cytology, and immunohistochemistry features, definitive diagnosis can be confidently made without the help of FISH in almost every case. Materials and Methods: Six histologically confirmed cases of SC were studied. The cytology slides of all the six cases were retrieved and reviewed to identify the characteristic features which could have helped in raising the possibility of SC on fine needle aspiration cytology itself. Cell blocks were also studied, wherever available. Results: Patients were all male with average age of 35.2 years. The six cases in the current study demonstrated at least focal cytoplasmic vacuolization of varying sizes, papillae formations, and bland nuclear features on fine needle aspirate smears. It was also seen that S-100 and mammaglobin immunohistochemistry (IHC) are very helpful in confirming the diagnosis. Conclusions: The results of the current study highlight the cytomorphological features which may help in clinching the diagnosis SC on cytology itself. They also highlight certain cytological features which help to rule out the other differential diagnoses.