While they may be what Andy and jippie say, they also MAY be "MMIC"s
Wikipedia - MMIC aka Monolithic microwave integrated circuit.
These often have a 4 lead package with 2 opposite pins being ground, but this is not essential. And a transistor may also have 4 leads with two being ground. The image below is from the above Wikipedia page.
However, to rather meld the answers given - a MMIC "IC" MAY be as simple as a single transistor with internal biasing resistors. Or a pair of transistors. Or much more.
The diagram below is a Mini-Circuits ERA series MMIC amplifier.
Diagram from Mini-Circuits AN-60-10 BIASING MMIC AMPLIFIERS - e.g., ERA SERIES
Which ends up in circuit diagrams looking like this:
This one actually uses all 4 pins for different functions - so yours is not one of these :
BUT, some of these could be - Table 15 from this useful page
But, ALL of these with 4 leads are transistors intended for LNA use (table 1).