Closely resembles normal prostate. Glands are small, well-formed, closely packed.
Increased stroma with well-formed glands, but larger with more tissue between them.
Recognizable glands, but cells are darker. Some cells have left the glands and are beginning to invade the surrounding tissue or have an infiltrative pattern.
Few recognizable glands. Many cells invading the surrounding tissue in clumps.
Few or no recognizable glands. Often sheets of cells throughout the surrounding tissue.