#FNAFriday: How cytopathologists learn, teach, and share knowledge on Twitter.

BACKGROUND: Twitter is an expanding social media network among cytopathologists to share knowledge. Tweets are made up of text which may also include images or video. All tweets labeled under a hashtag can be tracked. The #FNAFriday hashtag was created in 2015 by one of the authors (X.J.) to build a community of individuals, to educate and share interesting cases, and highlight a variety of diagnoses with FNA specimens. METHODS: We retrospectively extracted all tweets labeled with #FNAFriday from April 2015 to mid-February 2019 (47 mo) using the Twitter search engine. The data point included: author, number of figures, type of cytology-stain, use of immunocytochemistry, histochemistry or molecular techniques, and the subspeciality. The educational content was categorized as: live-tweeting, training activities, and publication references. The number if comments, retweets and likes was also recorded. RESULTS: A total of 349 original tweets using #FNAFriday were tracked with an average of 7.43 tweets/month. We describe the "top three" countries with most tweets, active users and subspecialties. The most frequent stain was Papanicolau and part of the content of the tweets was using cellblock (14.04%), histologic correlation (10.03%), immunocytochemistry (8.60%), molecular tests (2.01%), gross pictures (4.58%), and radiologic pictures (3.4%). CONCLUSION: The presence of cytopathologists on Twitter who want to share their cases has increased. The weekly FNAFriday label with other cytology hashtags is a specific keyword for those interested in the field.