The phrase "a fascinating case of" is correct and usable in written English.
You can use it when discussing an interesting example or situation that illustrates a particular phenomenon or concept.
Example: "The study of the rare bird species in the Amazon presents a fascinating case of adaptation to extreme environmental changes."
Alternatives: "an intriguing example of" or "a compelling instance of".
I am quoting from the published script in a fascinating case of collaboration.
Tune in next week for a fascinating case of malnutrition in a photogenic child?
In "Close-Up," Abbas Kiarostami hired the opposing sides of a criminal trial to play themselves in a fascinating case of impersonation and fraud.
On Wednesday I challenged readers to figure out a fascinating case of a 52-year-old father of two disabled sons who experienced sudden weakness in his legs, low potassium and hyperthyroidism.
Beethoven carried on the tradition — the darkly rumbling cadenza that he devised for Mozart's D-minor Piano Concerto is a fascinating case of one composer meditating on another — but he also helped to kill it.
Written on Skin (2012), by George Benjamin, with a libretto by Martin Crimp, is a fascinating case of a contemporary opera that manages to inhabit both the template of its genre and to subvert it.
The Republic of Ireland offers a fascinating case for exploring discourses around rurality and housing development, due to the country's relatively permissive planning policy and impressive rural housing output during the boom period.
These derive their name from a fascinating case example of a woman who came out of her depressed state during a family therapy session when her cocker spaniel licked her face.
It's this quiet period -- as Dreier is left alone to contemplate what he did, the freedoms he'll lose, and how much of his kids' lives he'll be missing -- that we never got from Bernie Madoff, making Unraveled a fascinating case study of the kind of personality that would commit such a monumental crime.
Siddiqi's paper provides a fascinating case study of how the development of funded programmes to support both public health aims and rights-claiming has resulted in a bureaucratisation of sexual identities which is at odds with people's lived experience.
I think pens, in this case, are a fascinating case study of the value and danger of crowdfunding.
