The phrase "a fashionable topic" is correct and usable in written English.
It can be used to describe a subject that is currently popular or trendy in discussions or media.
Example: "Sustainable fashion has become a fashionable topic among influencers and consumers alike."
Alternatives: "a trendy subject" or "a popular theme".
The teaching profession has become a fashionable topic among education reformers around the world.
More widely, Icelandic exceptionalism has been a fashionable topic for some time.
The comedian uses the C.I.A. as a fashionable topic, but he doesn't touch it or connect to it.
For 30 years, he has been creatively interpreting speciality dishes from the surrounding Dorgali region, using local produce long before "food miles" became a fashionable topic.
It is what is known as a high incidence disorder, but not as high as cerebral palsy and nowhere near the levels needed to make it a fashionable topic.
As a fashionable topic in computer vision, fine-grained image recognition has been attracting increasingly attention from both academia and industry in the past few years.
This is a very fashionable topic among film-writers: the allegedly contemporary phenomenon of watching films outside the cinema.
Asteroids are a very fashionable topic for scientific study at the moment.
"It's an extremely fashionable topic right now.
Meanwhile, Caucasian solidarity is an increasingly fashionable topic in Tbilisi, which last year hosted two conferences on Russian atrocities against the Circassians, an ethnic group driven out of the region in the late czarist period.
The world has been getting less equal for decades, but last year, rising inequality became an especially fashionable topic of discussion, in no small part because of the release of the economist Thomas Piketty's book "Capital in the Twenty-First Century" (which John Cassidy reviewed in the magazine), a discussion of the divergence between the world's rich and poor.
