The phrase "a special subset of" is correct and usable in written English.
It can be used when referring to a specific group that is part of a larger category, often to highlight unique characteristics or features.
Example: "In mathematics, prime numbers are a special subset of natural numbers that have only two distinct positive divisors."
Alternatives: "a distinct category of" or "a unique group of".
Langerhans cells (LC) are a special subset of dendritic cells integrating cutaneous immunity.
Naturally occurring proteins comprise a special subset of all plausible sequences and structures selected through evolution.
is all, or only a special subset, of behavior both a cause and a consequence of evolution?
"Firms in software, electronics (including instruments, semiconductors and computers) and biotech form a special subset of MIT-related companies.
A special subset of these proteins, known to biologists as tyrosine kinases, are particularly prone to go awry and show up in hyperactive form in many human cancers.
It was in this latter area and in a special subset of these, the Hodge manifolds, that he achieved some of his most important results.
Much of the more recent research in this vein suggests that Tea Party conservatives and their political leaders in and out of Congress are a special subset within the broader universe of conservatives.
Although every cell possesses its own full copy of the genome, each type is thought to use only its own special subset of the genes, the rest being permanently switched off.
In many ways, though, they are kindred spirits in the clubby culture of the Senate in that both are appropriators, that special subset of lawmakers who serve on the Senate's most powerful committee, which allocates spending.
This could be bad news for the special subset of Moscow's strays who, in the unregulated aftermath of the Soviet Union, learned to descend the stations' vertiginous escalators and, like true urbanites, now regularly navigate Moscow by metro, sparing their paws as they roam the megalopolis to forage for meals, meet new people, check out unfamiliar neighborhoods, or, on occasion, just for kicks.
Relatively small sample size of this special subset of cataract patients.
